JSON functions

BigQuery supports the following functions, which can retrieve and transform JSON data.

Function overview

Standard JSON extraction functions (recommended)

The following functions use double quotes to escape invalid JSONPath characters: "a.b".

This behavior is consistent with the ANSI standard.

JSON function	Description	Return type
JSON_QUERY	Extracts a JSON value, such as an array or object, or a JSON scalar value, such as a string, number, or boolean.	JSON-formatted STRING or JSON
JSON_VALUE	Extracts a scalar value. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the values. Returns a SQL NULL if a non-scalar value is selected.	STRING
JSON_QUERY_ARRAY	Extracts an array of JSON values, such as arrays or objects, and JSON scalar values, such as strings, numbers, and booleans.	ARRAY<JSON-formatted STRING> or ARRAY<JSON>
JSON_VALUE_ARRAY	Extracts an array of scalar values. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the values. Returns a SQL NULL if the selected value is not an array or not an array containing only scalar values.	ARRAY<STRING>

Legacy JSON extraction functions

The following functions use single quotes and brackets to escape invalid JSONPath characters: ['a.b'].

While these functions are supported by BigQuery, we recommend using the functions in the previous table.

JSON function	Description	Return type
JSON_EXTRACT	Extracts a JSON value, such as an array or object, or a JSON scalar value, such as a string, number, or boolean.	JSON-formatted STRING or JSON
JSON_EXTRACT_SCALAR	Extracts a scalar value. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the values. Returns a SQL NULL if a non-scalar value is selected.	STRING
JSON_EXTRACT_ARRAY	Extracts an array of JSON values, such as arrays or objects, and JSON scalar values, such as strings, numbers, and booleans.	ARRAY<JSON-formatted STRING> or ARRAY<JSON>
JSON_EXTRACT_STRING_ARRAY	Extracts an array of scalar values. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the values. Returns a SQL NULL if the selected value is not an array or not an array containing only scalar values.	ARRAY<STRING>

Other JSON functions

JSON function	Description	Return type
PARSE_JSON	Takes a JSON-formatted string and returns a JSON value.	JSON
TO_JSON	Takes a SQL value and returns a JSON value.	JSON
TO_JSON_STRING	Takes a SQL value and returns a JSON-formatted string representation of the value.	JSON-formatted STRING
STRING	Extracts a string from JSON.	STRING
BOOL	Extracts a boolean from JSON.	BOOL
INT64	Extracts a 64-bit integer from JSON.	INT64
FLOAT64	Extracts a 64-bit floating-point number from JSON.	FLOAT64
JSON_TYPE	Returns the type of the outermost JSON value as a string.	STRING

JSON_EXTRACT

JSON_EXTRACT(json_string_expr, json_path)

JSON_EXTRACT(json_expr, json_path)

Description

Extracts a JSON value, such as an array or object, or a JSON scalar value, such as a string, number, or boolean. If a JSON key uses invalid JSONPath characters, then you can escape those characters using single quotes and brackets.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

  Extracts a SQL NULL when a JSON-formatted string null is encountered. For example:

  SELECT JSON_EXTRACT("null", "$") -- Returns a SQL NULL
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

  Extracts a JSON null when a JSON null is encountered.

  SELECT JSON_EXTRACT(JSON 'null', "$") -- Returns a JSON 'null'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input.

Return type

• json_string_expr: A JSON-formatted STRING
• json_expr: JSON

Examples

In the following example, JSON data is extracted and returned as JSON.

SELECT
  JSON_EXTRACT(JSON '{"class":{"students":[{"id":5},{"id":12}]}}', '$.class')
  AS json_data;

+-----------------------------------+
| json_data                         |
+-----------------------------------+
| {"students":[{"id":5},{"id":12}]} |
+-----------------------------------+

In the following examples, JSON data is extracted and returned as JSON-formatted strings.

SELECT JSON_EXTRACT(json_text, '$') AS json_text_string
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------------------------------------------------+
| json_text_string                                          |
+-----------------------------------------------------------+
| {"class":{"students":[{"name":"Jane"}]}}                  |
| {"class":{"students":[]}}                                 |
| {"class":{"students":[{"name":"John"},{"name":"Jamie"}]}} |
+-----------------------------------------------------------+

SELECT JSON_EXTRACT(json_text, '$.class.students[0]') AS first_student
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------+
| first_student   |
+-----------------+
| {"name":"Jane"} |
| NULL            |
| {"name":"John"} |
+-----------------+

SELECT JSON_EXTRACT(json_text, '$.class.students[1].name') AS second_student_name
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name" : null}]}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-------------------+
| second_student    |
+-------------------+
| NULL              |
| NULL              |
| NULL              |
| "Jamie"           |
+-------------------+

SELECT JSON_EXTRACT(json_text, "$.class['students']") AS student_names
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+------------------------------------+
| student_names                      |
+------------------------------------+
| [{"name":"Jane"}]                  |
| []                                 |
| [{"name":"John"},{"name":"Jamie"}] |
+------------------------------------+

SELECT JSON_EXTRACT('{"a":null}', "$.a"); -- Returns a SQL NULL
SELECT JSON_EXTRACT('{"a":null}', "$.b"); -- Returns a SQL NULL

SELECT JSON_EXTRACT(JSON '{"a":null}', "$.a"); -- Returns a JSON 'null'
SELECT JSON_EXTRACT(JSON '{"a":null}', "$.b"); -- Returns a SQL NULL

JSON_QUERY

JSON_QUERY(json_string_expr, json_path)

JSON_QUERY(json_expr, json_path)

Description

Extracts a JSON value, such as an array or object, or a JSON scalar value, such as a string, number, or boolean. If a JSON key uses invalid JSONPath characters, then you can escape those characters using double quotes.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

  Extracts a SQL NULL when a JSON-formatted string null is encountered. For example:

  SELECT JSON_QUERY("null", "$") -- Returns a SQL NULL
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

  Extracts a JSON null when a JSON null is encountered.

  SELECT JSON_QUERY(JSON 'null', "$") -- Returns a JSON 'null'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input.

Return type

• json_string_expr: A JSON-formatted STRING
• json_expr: JSON

Examples

In the following example, JSON data is extracted and returned as JSON.

SELECT
  JSON_QUERY(JSON '{"class":{"students":[{"id":5},{"id":12}]}}', '$.class')
  AS json_data;

+-----------------------------------+
| json_data                         |
+-----------------------------------+
| {"students":[{"id":5},{"id":12}]} |
+-----------------------------------+

In the following examples, JSON data is extracted and returned as JSON-formatted strings.

SELECT JSON_QUERY(json_text, '$') AS json_text_string
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------------------------------------------------+
| json_text_string                                          |
+-----------------------------------------------------------+
| {"class":{"students":[{"name":"Jane"}]}}                  |
| {"class":{"students":[]}}                                 |
| {"class":{"students":[{"name":"John"},{"name":"Jamie"}]}} |
+-----------------------------------------------------------+

SELECT JSON_QUERY(json_text, '$.class.students[0]') AS first_student
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-----------------+
| first_student   |
+-----------------+
| {"name":"Jane"} |
| NULL            |
| {"name":"John"} |
+-----------------+

SELECT JSON_QUERY(json_text, '$.class.students[1].name') AS second_student_name
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name" : null}]}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+-------------------+
| second_student    |
+-------------------+
| NULL              |
| NULL              |
| NULL              |
| "Jamie"           |
+-------------------+

SELECT JSON_QUERY(json_text, '$.class."students"') AS student_names
FROM UNNEST([
  '{"class" : {"students" : [{"name" : "Jane"}]}}',
  '{"class" : {"students" : []}}',
  '{"class" : {"students" : [{"name" : "John"}, {"name": "Jamie"}]}}'
  ]) AS json_text;

+------------------------------------+
| student_names                      |
+------------------------------------+
| [{"name":"Jane"}]                  |
| []                                 |
| [{"name":"John"},{"name":"Jamie"}] |
+------------------------------------+

SELECT JSON_QUERY('{"a":null}', "$.a"); -- Returns a SQL NULL
SELECT JSON_QUERY('{"a":null}', "$.b"); -- Returns a SQL NULL

SELECT JSON_QUERY(JSON '{"a":null}', "$.a"); -- Returns a JSON 'null'
SELECT JSON_QUERY(JSON '{"a":null}', "$.b"); -- Returns a SQL NULL

JSON_EXTRACT_SCALAR

JSON_EXTRACT_SCALAR(json_string_expr[, json_path])

JSON_EXTRACT_SCALAR(json_expr[, json_path])

Description

Extracts a scalar value and then returns it as a string. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the return values. If a JSON key uses invalid JSONPath characters, then you can escape those characters using single quotes and brackets.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

  If json_path returns a JSON null or a non-scalar value (in other words, if json_path refers to an object or an array), then a SQL NULL is returned.

Return type

STRING

Examples

In the following example, age is extracted.

SELECT JSON_EXTRACT_SCALAR(JSON '{ "name" : "Jakob", "age" : "6" }', '$.age') AS scalar_age;

+------------+
| scalar_age |
+------------+
| 6          |
+------------+

The following example compares how results are returned for the JSON_EXTRACT and JSON_EXTRACT_SCALAR functions.

SELECT JSON_EXTRACT('{ "name" : "Jakob", "age" : "6" }', '$.name') AS json_name,
  JSON_EXTRACT_SCALAR('{ "name" : "Jakob", "age" : "6" }', '$.name') AS scalar_name,
  JSON_EXTRACT('{ "name" : "Jakob", "age" : "6" }', '$.age') AS json_age,
  JSON_EXTRACT_SCALAR('{ "name" : "Jakob", "age" : "6" }', '$.age') AS scalar_age;

+-----------+-------------+----------+------------+
| json_name | scalar_name | json_age | scalar_age |
+-----------+-------------+----------+------------+
| "Jakob"   | Jakob       | "6"      | 6          |
+-----------+-------------+----------+------------+

SELECT JSON_EXTRACT('{"fruits": ["apple", "banana"]}', '$.fruits') AS json_extract,
  JSON_EXTRACT_SCALAR('{"fruits": ["apple", "banana"]}', '$.fruits') AS json_extract_scalar;

+--------------------+---------------------+
| json_extract       | json_extract_scalar |
+--------------------+---------------------+
| ["apple","banana"] | NULL                |
+--------------------+---------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets, [' ']. For example:

SELECT JSON_EXTRACT_SCALAR('{"a.b": {"c": "world"}}', "$['a.b'].c") AS hello;

+-------+
| hello |
+-------+
| world |
+-------+

JSON_VALUE

JSON_VALUE(json_string_expr[, json_path])

JSON_VALUE(json_expr[, json_path])

Description

Extracts a scalar value and then returns it as a string. A scalar value can represent a string, number, or boolean. Removes the outermost quotes and unescapes the return values. If a JSON key uses invalid JSONPath characters, then you can escape those characters using double quotes.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

  If json_path returns a JSON null or a non-scalar value (in other words, if json_path refers to an object or an array), then a SQL NULL is returned.

Return type

STRING

Examples

In the following example, JSON data is extracted and returned as a scalar value.

SELECT JSON_VALUE(JSON '{ "name" : "Jakob", "age" : "6" }', '$.age') AS scalar_age;

+------------+
| scalar_age |
+------------+
| 6          |
+------------+

The following example compares how results are returned for the JSON_QUERY and JSON_VALUE functions.

SELECT JSON_QUERY('{ "name" : "Jakob", "age" : "6" }', '$.name') AS json_name,
  JSON_VALUE('{ "name" : "Jakob", "age" : "6" }', '$.name') AS scalar_name,
  JSON_QUERY('{ "name" : "Jakob", "age" : "6" }', '$.age') AS json_age,
  JSON_VALUE('{ "name" : "Jakob", "age" : "6" }', '$.age') AS scalar_age;

+-----------+-------------+----------+------------+
| json_name | scalar_name | json_age | scalar_age |
+-----------+-------------+----------+------------+
| "Jakob"   | Jakob       | "6"      | 6          |
+-----------+-------------+----------+------------+

SELECT JSON_QUERY('{"fruits": ["apple", "banana"]}', '$.fruits') AS json_query,
  JSON_VALUE('{"fruits": ["apple", "banana"]}', '$.fruits') AS json_value;

+--------------------+------------+
| json_query         | json_value |
+--------------------+------------+
| ["apple","banana"] | NULL       |
+--------------------+------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes. For example:

SELECT JSON_VALUE('{"a.b": {"c": "world"}}', '$."a.b".c') AS hello;

+-------+
| hello |
+-------+
| world |
+-------+

JSON_EXTRACT_ARRAY

JSON_EXTRACT_ARRAY(json_string_expr[, json_path])

JSON_EXTRACT_ARRAY(json_expr[, json_path])

Description

Extracts an array of JSON values, such as arrays or objects, and JSON scalar values, such as strings, numbers, and booleans. If a JSON key uses invalid JSONPath characters, then you can escape those characters using single quotes and brackets.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

Return type

• json_string_expr: ARRAY<JSON-formatted STRING>
• json_expr: ARRAY<JSON>

Examples

This extracts items in JSON to an array of JSON values:

SELECT JSON_EXTRACT_ARRAY(
  JSON '{"fruits":["apples","oranges","grapes"]}','$.fruits'
  ) AS json_array;

+---------------------------------+
| json_array                      |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

This extracts the items in a JSON-formatted string to a string array:

SELECT JSON_EXTRACT_ARRAY('[1,2,3]') AS string_array;

+--------------+
| string_array |
+--------------+
| [1, 2, 3]    |
+--------------+

This extracts a string array and converts it to an integer array:

SELECT ARRAY(
  SELECT CAST(integer_element AS INT64)
  FROM UNNEST(
    JSON_EXTRACT_ARRAY('[1,2,3]','$')
  ) AS integer_element
) AS integer_array;

+---------------+
| integer_array |
+---------------+
| [1, 2, 3]     |
+---------------+

This extracts string values in a JSON-formatted string to an array:

-- Doesn't strip the double quotes
SELECT JSON_EXTRACT_ARRAY('["apples","oranges","grapes"]', '$') AS string_array;

+---------------------------------+
| string_array                    |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

-- Strips the double quotes
SELECT ARRAY(
  SELECT JSON_EXTRACT_SCALAR(string_element, '$')
  FROM UNNEST(JSON_EXTRACT_ARRAY('["apples","oranges","grapes"]','$')) AS string_element
) AS string_array;

+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

This extracts only the items in the fruit property to an array:

SELECT JSON_EXTRACT_ARRAY(
  '{"fruit":[{"apples":5,"oranges":10},{"apples":2,"oranges":4}],"vegetables":[{"lettuce":7,"kale": 8}]}',
  '$.fruit'
) AS string_array;

+-------------------------------------------------------+
| string_array                                          |
+-------------------------------------------------------+
| [{"apples":5,"oranges":10}, {"apples":2,"oranges":4}] |
+-------------------------------------------------------+

These are equivalent:

SELECT JSON_EXTRACT_ARRAY('{"fruits":["apples","oranges","grapes"]}','$[fruits]') AS string_array;

SELECT JSON_EXTRACT_ARRAY('{"fruits":["apples","oranges","grapes"]}','$.fruits') AS string_array;

-- The queries above produce the following result:
+---------------------------------+
| string_array                    |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets, [' ']. For example:

SELECT JSON_EXTRACT_ARRAY('{"a.b": {"c": ["world"]}}', "$['a.b'].c") AS hello;

+-----------+
| hello     |
+-----------+
| ["world"] |
+-----------+

The following examples explore how invalid requests and empty arrays are handled:

• If a JSONPath is invalid, an error is thrown.
• If a JSON-formatted string is invalid, the output is NULL.
• It is okay to have empty arrays in the JSON-formatted string.

-- An error is thrown if you provide an invalid JSONPath.
SELECT JSON_EXTRACT_ARRAY('["foo","bar","baz"]','INVALID_JSONPath') AS result;

-- If the JSONPath does not refer to an array, then NULL is returned.
SELECT JSON_EXTRACT_ARRAY('{"a":"foo"}','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a key that does not exist is specified, then the result is NULL.
SELECT JSON_EXTRACT_ARRAY('{"a":"foo"}','$.b') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- Empty arrays in JSON-formatted strings are supported.
SELECT JSON_EXTRACT_ARRAY('{"a":"foo","b":[]}','$.b') AS result;

+--------+
| result |
+--------+
| []     |
+--------+

JSON_QUERY_ARRAY

JSON_QUERY_ARRAY(json_string_expr[, json_path])

JSON_QUERY_ARRAY(json_expr[, json_path])

Description

Extracts an array of JSON values, such as arrays or objects, and JSON scalar values, such as strings, numbers, and booleans. If a JSON key uses invalid JSONPath characters, then you can escape those characters using double quotes.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

Return type

• json_string_expr: ARRAY<JSON-formatted STRING>
• json_expr: ARRAY<JSON>

Examples

This extracts items in JSON to an array of JSON values:

SELECT JSON_QUERY_ARRAY(
  JSON '{"fruits":["apples","oranges","grapes"]}','$.fruits'
  ) AS json_array;

+---------------------------------+
| json_array                      |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

This extracts the items in a JSON-formatted string to a string array:

SELECT JSON_QUERY_ARRAY('[1,2,3]') AS string_array;

+--------------+
| string_array |
+--------------+
| [1, 2, 3]    |
+--------------+

This extracts a string array and converts it to an integer array:

SELECT ARRAY(
  SELECT CAST(integer_element AS INT64)
  FROM UNNEST(
    JSON_QUERY_ARRAY('[1,2,3]','$')
  ) AS integer_element
) AS integer_array;

+---------------+
| integer_array |
+---------------+
| [1, 2, 3]     |
+---------------+

This extracts string values in a JSON-formatted string to an array:

-- Doesn't strip the double quotes
SELECT JSON_QUERY_ARRAY('["apples","oranges","grapes"]', '$') AS string_array;

+---------------------------------+
| string_array                    |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

-- Strips the double quotes
SELECT ARRAY(
  SELECT JSON_VALUE(string_element, '$')
  FROM UNNEST(JSON_QUERY_ARRAY('["apples","oranges","grapes"]','$')) AS string_element
) AS string_array;

+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

This extracts only the items in the fruit property to an array:

SELECT JSON_QUERY_ARRAY(
  '{"fruit":[{"apples":5,"oranges":10},{"apples":2,"oranges":4}],"vegetables":[{"lettuce":7,"kale": 8}]}',
  '$.fruit'
) AS string_array;

+-------------------------------------------------------+
| string_array                                          |
+-------------------------------------------------------+
| [{"apples":5,"oranges":10}, {"apples":2,"oranges":4}] |
+-------------------------------------------------------+

These are equivalent:

SELECT JSON_QUERY_ARRAY('{"fruits":["apples","oranges","grapes"]}','$.fruits') AS string_array;

SELECT JSON_QUERY_ARRAY('{"fruits":["apples","oranges","grapes"]}','$."fruits"') AS string_array;

-- The queries above produce the following result:
+---------------------------------+
| string_array                    |
+---------------------------------+
| ["apples", "oranges", "grapes"] |
+---------------------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes: " ". For example:

SELECT JSON_QUERY_ARRAY('{"a.b": {"c": ["world"]}}', '$."a.b".c') AS hello;

+-----------+
| hello     |
+-----------+
| ["world"] |
+-----------+

The following examples show how invalid requests and empty arrays are handled:

-- An error is returned if you provide an invalid JSONPath.
SELECT JSON_QUERY_ARRAY('["foo","bar","baz"]','INVALID_JSONPath') AS result;

-- If the JSONPath does not refer to an array, then NULL is returned.
SELECT JSON_QUERY_ARRAY('{"a":"foo"}','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a key that does not exist is specified, then the result is NULL.
SELECT JSON_QUERY_ARRAY('{"a":"foo"}','$.b') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- Empty arrays in JSON-formatted strings are supported.
SELECT JSON_QUERY_ARRAY('{"a":"foo","b":[]}','$.b') AS result;

+--------+
| result |
+--------+
| []     |
+--------+

JSON_EXTRACT_STRING_ARRAY

JSON_EXTRACT_STRING_ARRAY(json_string_expr[, json_path])

JSON_EXTRACT_STRING_ARRAY(json_expr[, json_path])

Description

Extracts an array of scalar values and returns an array of string-formatted scalar values. A scalar value can represent a string, number, or boolean. If a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

Caveats:

• A JSON null in the input array produces a SQL NULL as the output for that JSON null. If the output contains a NULL array element, an error is produced because the final output cannot be an array with NULL values.
• If a JSONPath matches an array that contains scalar objects and a JSON null, then the output of the function must be transformed because the final output cannot be an array with NULL values.

Return type

ARRAY<STRING>

Examples

This extracts items in JSON to a string array:

SELECT JSON_EXTRACT_STRING_ARRAY(
  JSON '{"fruits":["apples","oranges","grapes"]}','$.fruits'
  ) AS string_array;

+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

The following example compares how results are returned for the JSON_EXTRACT_ARRAY and JSON_EXTRACT_STRING_ARRAY functions.

SELECT JSON_EXTRACT_ARRAY('["apples","oranges"]') AS json_array,
JSON_EXTRACT_STRING_ARRAY('["apples","oranges"]') AS string_array;

+-----------------------+-------------------+
| json_array            | string_array      |
+-----------------------+-------------------+
| ["apples", "oranges"] | [apples, oranges] |
+-----------------------+-------------------+

This extracts the items in a JSON-formatted string to a string array:

-- Strips the double quotes
SELECT JSON_EXTRACT_STRING_ARRAY('["foo","bar","baz"]','$') AS string_array;

+-----------------+
| string_array    |
+-----------------+
| [foo, bar, baz] |
+-----------------+

This extracts a string array and converts it to an integer array:

SELECT ARRAY(
  SELECT CAST(integer_element AS INT64)
  FROM UNNEST(
    JSON_EXTRACT_STRING_ARRAY('[1,2,3]','$')
  ) AS integer_element
) AS integer_array;

+---------------+
| integer_array |
+---------------+
| [1, 2, 3]     |
+---------------+

These are equivalent:

SELECT JSON_EXTRACT_STRING_ARRAY('{"fruits":["apples","oranges","grapes"]}','$[fruits]') AS string_array;

SELECT JSON_EXTRACT_STRING_ARRAY('{"fruits":["apples","oranges","grapes"]}','$.fruits') AS string_array;

-- The queries above produce the following result:
+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using single quotes and brackets: [' ']. For example:

SELECT JSON_EXTRACT_STRING_ARRAY('{"a.b": {"c": ["world"]}}', "$['a.b'].c") AS hello;

+---------+
| hello   |
+---------+
| [world] |
+---------+

The following examples explore how invalid requests and empty arrays are handled:

-- An error is thrown if you provide an invalid JSONPath.
SELECT JSON_EXTRACT_STRING_ARRAY('["foo","bar","baz"]','INVALID_JSONPath') AS result;

-- If the JSON formatted string is invalid, then NULL is returned.
SELECT JSON_EXTRACT_STRING_ARRAY('}}','$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If the JSON document is NULL, then NULL is returned.
SELECT JSON_EXTRACT_STRING_ARRAY(NULL,'$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath does not match anything, then the output is NULL.
SELECT JSON_EXTRACT_STRING_ARRAY('{"a":["foo","bar","baz"]}','$.b') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an object that is not an array, then the output is NULL.
SELECT JSON_EXTRACT_STRING_ARRAY('{"a":"foo"}','$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an array of non-scalar objects, then the output is NULL.
SELECT JSON_EXTRACT_STRING_ARRAY('{"a":[{"b":"foo","c":1},{"b":"bar","c":2}],"d":"baz"}','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an array of mixed scalar and non-scalar objects, then the output is NULL.
SELECT JSON_EXTRACT_STRING_ARRAY('{"a":[10, {"b": 20}]','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an empty JSON array, then the output is an empty array instead of NULL.
SELECT JSON_EXTRACT_STRING_ARRAY('{"a":"foo","b":[]}','$.b') AS result;

+--------+
| result |
+--------+
| []     |
+--------+

-- The following query produces and error because the final output cannot be an
-- array with NULLs.
SELECT JSON_EXTRACT_STRING_ARRAY('["world", 1, null]') AS result;

JSON_VALUE_ARRAY

JSON_VALUE_ARRAY(json_string_expr[, json_path])

JSON_VALUE_ARRAY(json_expr[, json_path])

Description

Extracts an array of scalar values and returns an array of string-formatted scalar values. A scalar value can represent a string, number, or boolean. If a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes.

• json_string_expr: A JSON-formatted string. For example:

  '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_expr: JSON. For example:

  JSON '{"class" : {"students" : [{"name" : "Jane"}]}}'
  

• json_path: The JSONPath. This identifies the data that you want to obtain from the input. If this optional parameter is not provided, then the JSONPath $ symbol is applied, which means that all of the data is analyzed.

Caveats:

• A JSON null in the input array produces a SQL NULL as the output for JSON null. If the output contains a NULL array element, an error is produced because the final output cannot be an array with NULL values.
• If a JSONPath matches an array that contains scalar objects and a JSON null, then the output of the function must be transformed because the final output cannot be an array with NULL values.

Return type

ARRAY<STRING>

Examples

This extracts items in JSON to a string array:

SELECT JSON_VALUE_ARRAY(
  JSON '{"fruits":["apples","oranges","grapes"]}','$.fruits'
  ) AS string_array;

+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

The following example compares how results are returned for the JSON_QUERY_ARRAY and JSON_VALUE_ARRAY functions.

SELECT JSON_QUERY_ARRAY('["apples","oranges"]') AS json_array,
       JSON_VALUE_ARRAY('["apples","oranges"]') AS string_array;

+-----------------------+-------------------+
| json_array            | string_array      |
+-----------------------+-------------------+
| ["apples", "oranges"] | [apples, oranges] |
+-----------------------+-------------------+

This extracts the items in a JSON-formatted string to a string array:

-- Strips the double quotes
SELECT JSON_VALUE_ARRAY('["foo","bar","baz"]','$') AS string_array;

+-----------------+
| string_array    |
+-----------------+
| [foo, bar, baz] |
+-----------------+

This extracts a string array and converts it to an integer array:

SELECT ARRAY(
  SELECT CAST(integer_element AS INT64)
  FROM UNNEST(
    JSON_VALUE_ARRAY('[1,2,3]','$')
  ) AS integer_element
) AS integer_array;

+---------------+
| integer_array |
+---------------+
| [1, 2, 3]     |
+---------------+

These are equivalent:

SELECT JSON_VALUE_ARRAY('{"fruits":["apples","oranges","grapes"]}','$.fruits') AS string_array;
SELECT JSON_VALUE_ARRAY('{"fruits":["apples","oranges","grapes"]}','$."fruits"') AS string_array;

-- The queries above produce the following result:
+---------------------------+
| string_array              |
+---------------------------+
| [apples, oranges, grapes] |
+---------------------------+

In cases where a JSON key uses invalid JSONPath characters, you can escape those characters using double quotes: " ". For example:

SELECT JSON_VALUE_ARRAY('{"a.b": {"c": ["world"]}}', '$."a.b".c') AS hello;

+---------+
| hello   |
+---------+
| [world] |
+---------+

The following examples explore how invalid requests and empty arrays are handled:

-- An error is thrown if you provide an invalid JSONPath.
SELECT JSON_VALUE_ARRAY('["foo","bar","baz"]','INVALID_JSONPath') AS result;

-- If the JSON-formatted string is invalid, then NULL is returned.
SELECT JSON_VALUE_ARRAY('}}','$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If the JSON document is NULL, then NULL is returned.
SELECT JSON_VALUE_ARRAY(NULL,'$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath does not match anything, then the output is NULL.
SELECT JSON_VALUE_ARRAY('{"a":["foo","bar","baz"]}','$.b') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an object that is not an array, then the output is NULL.
SELECT JSON_VALUE_ARRAY('{"a":"foo"}','$') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an array of non-scalar objects, then the output is NULL.
SELECT JSON_VALUE_ARRAY('{"a":[{"b":"foo","c":1},{"b":"bar","c":2}],"d":"baz"}','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an array of mixed scalar and non-scalar objects,
-- then the output is NULL.
SELECT JSON_VALUE_ARRAY('{"a":[10, {"b": 20}]','$.a') AS result;

+--------+
| result |
+--------+
| NULL   |
+--------+

-- If a JSONPath matches an empty JSON array, then the output is an empty array instead of NULL.
SELECT JSON_VALUE_ARRAY('{"a":"foo","b":[]}','$.b') AS result;

+--------+
| result |
+--------+
| []     |
+--------+

-- The following query produces and error because the final output cannot be an
-- array with NULLs.
SELECT JSON_VALUE_ARRAY('["world", 1, null]') AS result;

PARSE_JSON

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PARSE_JSON(json_string_expr[, wide_number_mode=>{ 'exact' | 'round' }])

Description

Takes a SQL STRING value and returns a SQL JSON value. The STRING value represents a string-formatted JSON value.

This function supports an optional mandatory-named argument called wide_number_mode that determines how to handle numbers that cannot be stored in a JSON value without the loss of precision. If used, wide_number_mode must include one of these values:

• exact: Only accept numbers that can be stored without loss of precision. If a number that cannot be stored without loss of precision is encountered, the function throws an error.
• round: If a number that cannot be stored without loss of precision is encountered, attempt to round it to a number that can be stored without loss of precision. If the number cannot be rounded, the function throws an error.

If wide_number_mode is not used, the function implicitly includes wide_number_mode=>'exact'. If a number appears in a JSON object or array, the wide_number_mode argument is applied to the number in the object or array.

Numbers from the following domains can be stored in JSON without loss of precision:

• 64-bit signed/unsigned integers, such as INT64
• FLOAT64

Return type

JSON

Examples

In the following example, a JSON-formatted string is converted to JSON.

SELECT PARSE_JSON('{"coordinates":[10,20],"id":1}') AS json_data;

+--------------------------------+
| json_data                      |
+--------------------------------+
| {"coordinates":[10,20],"id":1} |
+--------------------------------+

The following queries fail because:

• The number that was passed in cannot be stored without loss of precision.
• wide_number_mode=>'exact' is used implicitly in the first query and explicitly in the second query.

SELECT PARSE_JSON('{"id":922337203685477580701}') AS json_data; -- fails
SELECT PARSE_JSON('{"id":922337203685477580701}', wide_number_mode=>'exact') AS json_data; -- fails

The following query rounds the number to a number that can be stored in JSON.

SELECT PARSE_JSON('{"id":922337203685477580701}', wide_number_mode=>'round') AS json_data;

+--------------------------------+
| json_data                      |
+--------------------------------+
| {"id":9.223372036854776e+20}   |
+--------------------------------+

TO_JSON

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TO_JSON(sql_value[, stringify_wide_numbers=>{ TRUE | FALSE }])

Description

Takes a SQL value and returns a JSON value. The value must be a supported BigQuery data type. You can review the BigQuery data types that this function supports and their JSON encodings here.

This function supports an optional mandatory-named argument called stringify_wide_numbers.

• If this argument is TRUE, numeric values outside of the FLOAT64 type domain are encoded as strings.
• If this argument is not used or is FALSE, numeric values outside of the FLOAT64 type domain are not encoded as strings, but are stored as JSON numbers. If a numerical value cannot be stored in JSON without loss of precision, an error is thrown.

The following numerical data types are affected by the stringify_wide_numbers argument:

• INT64
• NUMERIC
• BIGNUMERIC

If one of these numerical data types appears in a container data type such as an ARRAY or STRUCT, the stringify_wide_numbers argument is applied to the numerical data types in the container data type.

Return type

A JSON value

Examples

In the following example, the query converts rows in a table to JSON values.

With CoordinatesTable AS (
    (SELECT 1 AS id, [10,20] AS coordinates) UNION ALL
    (SELECT 2 AS id, [30,40] AS coordinates) UNION ALL
    (SELECT 3 AS id, [50,60] AS coordinates))
SELECT TO_JSON(t) AS json_objects
FROM CoordinatesTable AS t;

+--------------------------------+
| json_objects                   |
+--------------------------------+
| {"coordinates":[10,20],"id":1} |
| {"coordinates":[30,40],"id":2} |
| {"coordinates":[50,60],"id":3} |
+--------------------------------+

In the following example, the query returns a large numerical value as a JSON string.

SELECT TO_JSON(9007199254740993, stringify_wide_numbers=>TRUE) as stringify_on

+--------------------+
| stringify_on       |
+--------------------+
| "9007199254740993" |
+--------------------+

In the following example, both queries return a large numerical value as a JSON number.

SELECT TO_JSON(9007199254740993, stringify_wide_numbers=>FALSE) as stringify_off
SELECT TO_JSON(9007199254740993) as stringify_off

+------------------+
| stringify_off    |
+------------------+
| 9007199254740993 |
+------------------+

In the following example, only large numeric values are converted to JSON strings.

With T1 AS (
  (SELECT 9007199254740993 AS id) UNION ALL
  (SELECT 2 AS id))
SELECT TO_JSON(t, stringify_wide_numbers=>TRUE) AS json_objects
FROM T1 AS t;

+---------------------------+
| json_objects              |
+---------------------------+
| {"id":"9007199254740993"} |
| {"id":2}                  |
+---------------------------+

In this example, the values 9007199254740993 (INT64) and 2.1 (FLOAT64) are converted to the common supertype FLOAT64, which is not affected by the stringify_wide_numbers argument.

With T1 AS (
  (SELECT 9007199254740993 AS id) UNION ALL
  (SELECT 2.1 AS id))
SELECT TO_JSON(t, stringify_wide_numbers=>TRUE) AS json_objects
FROM T1 AS t;

+------------------------------+
| json_objects                 |
+------------------------------+
| {"id":9.007199254740992e+15} |
| {"id":2.1}                   |
+------------------------------+

TO_JSON_STRING

TO_JSON_STRING(value[, pretty_print])

Description

Takes a SQL value and returns a JSON-formatted string representation of the value. The value must be a supported BigQuery data type. You can review the BigQuery data types that this function supports and their JSON encodings here.

This function supports an optional boolean parameter called pretty_print. If pretty_print is true, the returned value is formatted for easy readability.

Return type

A JSON-formatted STRING

Examples

Convert rows in a table to JSON-formatted strings.

With CoordinatesTable AS (
    (SELECT 1 AS id, [10,20] AS coordinates) UNION ALL
    (SELECT 2 AS id, [30,40] AS coordinates) UNION ALL
    (SELECT 3 AS id, [50,60] AS coordinates))
SELECT id, coordinates, TO_JSON_STRING(t) AS json_data
FROM CoordinatesTable AS t;

+----+-------------+--------------------------------+
| id | coordinates | json_data                      |
+----+-------------+--------------------------------+
| 1  | [10, 20]    | {"id":1,"coordinates":[10,20]} |
| 2  | [30, 40]    | {"id":2,"coordinates":[30,40]} |
| 3  | [50, 60]    | {"id":3,"coordinates":[50,60]} |
+----+-------------+--------------------------------+

Convert rows in a table to JSON-formatted strings that are easy to read.

With CoordinatesTable AS (
    (SELECT 1 AS id, [10,20] AS coordinates) UNION ALL
    (SELECT 2 AS id, [30,40] AS coordinates))
SELECT id, coordinates, TO_JSON_STRING(t, true) AS json_data
FROM CoordinatesTable AS t;

+----+-------------+--------------------+
| id | coordinates | json_data          |
+----+-------------+--------------------+
| 1  | [10, 20]    | {                  |
|    |             |   "id": 1,         |
|    |             |   "coordinates": [ |
|    |             |     10,            |
|    |             |     20             |
|    |             |   ]                |
|    |             | }                  |
+----+-------------+--------------------+
| 2  | [30, 40]    | {                  |
|    |             |   "id": 2,         |
|    |             |   "coordinates": [ |
|    |             |     30,            |
|    |             |     40             |
|    |             |   ]                |
|    |             | }                  |
+----+-------------+--------------------+

STRING

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STRING(json_expr)

Description

Takes a JSON expression, extracts a JSON string, and returns that value as a SQL STRING. If the expression is SQL NULL, the function returns SQL NULL. If the extracted JSON value is not a string, an error is produced.

• json_expr: JSON. For example:

  JSON '{"name": "sky", "color" : "blue"}'
  

Return type

STRING

Examples

SELECT STRING(JSON '"purple"') AS color;

+--------+
| color  |
+--------+
| purple |
+--------+

SELECT STRING(JSON_QUERY(JSON '{"name": "sky", "color": "blue"}', "$.color")) AS color;

+-------+
| color |
+-------+
| blue  |
+-------+

The following examples show how invalid requests are handled:

-- An error is thrown if the JSON is not of type string.
SELECT STRING(JSON '123') AS result; -- Throws an error
SELECT STRING(JSON 'null') AS result; -- Throws an error
SELECT SAFE.STRING(JSON '123') AS result; -- Returns a SQL NULL

BOOL

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BOOL(json_expr)

Description

Takes a JSON expression, extracts a JSON boolean, and returns that value as a SQL BOOL. If the expression is SQL NULL, the function returns SQL NULL. If the extracted JSON value is not a boolean, an error is produced.

• json_expr: JSON. For example:

  JSON '{"name": "sky", "color" : "blue"}'
  

Return type

BOOL

Examples

SELECT BOOL(JSON 'true') AS vacancy;

+---------+
| vacancy |
+---------+
| true    |
+---------+

SELECT BOOL(JSON_QUERY(JSON '{"hotel class": "5-star", "vacancy": true}', "$.vacancy")) AS vacancy;

+---------+
| vacancy |
+---------+
| true    |
+---------+

The following examples show how invalid requests are handled:

-- An error is thrown if JSON is not of type bool.
SELECT BOOL(JSON '123') AS result; -- Throws an error
SELECT BOOL(JSON 'null') AS result; -- Throw an error
SELECT SAFE.BOOL(JSON '123') AS result; -- Returns a SQL NULL

INT64

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INT64(json_expr)

Description

Takes a JSON expression, extracts a JSON number and returns that value as a SQL INT64. If the expression is SQL NULL, the function returns SQL NULL. If the extracted JSON number has a fractional part or is outside of the INT64 domain, an error is produced.

• json_expr: JSON. For example:

  JSON '{"name": "sky", "color" : "blue"}'
  

Return type

INT64

Examples

SELECT INT64(JSON '2005') AS flight_number;

+---------------+
| flight_number |
+---------------+
| 2005          |
+---------------+

SELECT INT64(JSON_QUERY(JSON '{"gate": "A4", "flight_number": 2005}', "$.flight_number")) AS flight_number;

+---------------+
| flight_number |
+---------------+
| 2005          |
+---------------+

SELECT INT64(JSON '10.0') AS score;

+-------+
| score |
+-------+
| 10    |
+-------+

The following examples show how invalid requests are handled:

-- An error is thrown if JSON is not a number or cannot be converted to a 64-bit integer.
SELECT INT64(JSON '10.1') AS result;  -- Throws an error
SELECT INT64(JSON '"strawberry"') AS result; -- Throws an error
SELECT INT64(JSON 'null') AS result; -- Throws an error
SELECT SAFE.INT64(JSON '"strawberry"') AS result;  -- Returns a SQL NULL

FLOAT64

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FLOAT64(json_expr[, wide_number_mode=>{ 'exact' | 'round' }])

Description

Takes a JSON expression, extracts a JSON number and returns that value as a SQL FLOAT64. If the expression is SQL NULL, the function returns SQL NULL. If the extracted JSON value is not a number, an error is produced.

• json_expr: JSON. For example:

  JSON '{"name": "sky", "color" : "blue"}'
  

This function supports an optional mandatory-named argument called wide_number_mode which defines what happens with a number that cannot be represented as a FLOAT64 without loss of precision.

This argument accepts one of the two case-sensitive values:

• ‘exact’: The function fails if the result cannot be represented as a FLOAT64 without loss of precision.
• ‘round’: The numeric value stored in JSON will be rounded to FLOAT64. If such rounding is not possible, the function fails. This is the default value if the argument is not specified.

Return type

FLOAT64

Examples

SELECT FLOAT64(JSON '9.8') AS velocity;

+----------+
| velocity |
+----------+
| 9.8      |
+----------+

SELECT FLOAT64(JSON_QUERY(JSON '{"vo2_max": 39.1, "age": 18}', "$.vo2_max")) AS vo2_max;

+---------+
| vo2_max |
+---------+
| 39.1    |
+---------+

SELECT FLOAT64(JSON '18446744073709551615', wide_number_mode=>'round') as result;

+------------------------+
| result                 |
+------------------------+
| 1.8446744073709552e+19 |
+------------------------+

SELECT FLOAT64(JSON '18446744073709551615') as result;

+------------------------+
| result                 |
+------------------------+
| 1.8446744073709552e+19 |
+------------------------+

The following examples show how invalid requests are handled:

-- An error is thrown if JSON is not of type FLOAT64.
SELECT FLOAT64(JSON '"strawberry"') AS result;
SELECT FLOAT64(JSON 'null') AS result;

-- An error is thrown because `wide_number_mode` is case-sensitive and not "exact" or "round".
SELECT FLOAT64(JSON '123.4', wide_number_mode=>'EXACT') as result;
SELECT FLOAT64(JSON '123.4', wide_number_mode=>'exac') as result;

-- An error is thrown because the number cannot be converted to DOUBLE without loss of precision
SELECT FLOAT64(JSON '18446744073709551615', wide_number_mode=>'exact') as result;

-- Returns a SQL NULL
SELECT SAFE.FLOAT64(JSON '"strawberry"') AS result;

JSON_TYPE

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JSON_TYPE(json_expr)

Description

Takes a JSON expression and returns the type of the outermost JSON value as a SQL STRING. The names of these JSON types can be returned:

• object
• array
• string
• number
• boolean
• null

If the expression is SQL NULL, the function returns SQL NULL. If the extracted JSON value is not a valid JSON type, an error is produced.

• json_expr: JSON. For example:

  JSON '{"name": "sky", "color" : "blue"}'
  

Return type

STRING

Examples

SELECT json_val, JSON_TYPE(json_val) AS type
FROM
  UNNEST(
    [
      JSON '"apple"',
      JSON '10',
      JSON '3.14',
      JSON 'null',
      JSON '{"city": "New York", "State": "NY"}',
      JSON '["apple", "banana"]',
      JSON 'false'
    ]
  ) AS json_val;

+----------------------------------+---------+
| json_val                         | type    |
+----------------------------------+---------+
| "apple"                          | string  |
| 10                               | number  |
| 3.14                             | number  |
| null                             | null    |
| {"State":"NY","city":"New York"} | object  |
| ["apple","banana"]               | array   |
| false                            | boolean |
+----------------------------------+---------+

JSON encodings

The following table includes common encodings that are used when a SQL value is encoded as JSON value with the TO_JSON_STRING or TO_JSON function.

From SQL	To JSON	Examples
NULL	null	SQL input: NULL JSON output: null
BOOL	boolean	SQL input: TRUE JSON output: true SQL input: FALSE JSON output: false
INT64	(TO_JSON_STRING only) number or string Encoded as a number when the value is in the range of [-2^53, 2^53], which is the range of integers that can be represented losslessly as IEEE 754 double-precision floating point numbers. A value outside of this range is encoded as a string.	SQL input: 9007199254740992 JSON output: 9007199254740992 SQL input: 9007199254740993 JSON output: "9007199254740993"
INT64	(TO_JSON only) number or string If the stringify_wide_numbers argument is TRUE and the value is outside of the FLOAT64 type domain, the value is encoded as a string. If the value cannot be stored in JSON without loss of precision, the function fails. Otherwise, the value is encoded as a number. If the stringify_wide_numbers is not used or is FALSE, numeric values outside of the `FLOAT64` type domain are not encoded as strings, but are stored as JSON numbers. If a numerical value cannot be stored in JSON without loss of precision, an error is thrown.	SQL input: 9007199254740992 JSON output: 9007199254740992 SQL input: 9007199254740993 JSON output: 9007199254740993 SQL input with stringify_wide_numbers=>TRUE: 9007199254740992 JSON output: 9007199254740992 SQL input with stringify_wide_numbers=>TRUE: 9007199254740993 JSON output: "9007199254740993"
NUMERIC BIGNUMERIC	(TO_JSON_STRING only) number or string Encoded as a number when the value is in the range of [-2^53, 2^53] and has no fractional part. A value outside of this range is encoded as a string.	SQL input: -1 JSON output: -1 SQL input: 0 JSON output: 0 SQL input: 9007199254740993 JSON output: "9007199254740993" SQL input: 123.56 JSON output: "123.56"
NUMERIC BIGNUMERIC	(TO_JSON only) number or string If the stringify_wide_numbers argument is TRUE and the value is outside of the FLOAT64 type domain, it is encoded as a string. Otherwise, it's encoded as a number.	SQL input: -1 JSON output: -1 SQL input: 0 JSON output: 0 SQL input: 9007199254740993 JSON output: 9007199254740993 SQL input: 123.56 JSON output: 123.56 SQL input with stringify_wide_numbers=>TRUE: 9007199254740993 JSON output: "9007199254740993" SQL input with stringify_wide_numbers=>TRUE: 123.56 JSON output: 123.56
FLOAT64	number or string +/-inf and NaN are encoded as Infinity, -Infinity, and NaN. Otherwise, this value is encoded as a number.	SQL input: 1.0 JSON output: 1 SQL input: 9007199254740993 JSON output: 9007199254740993 SQL input: "+inf" JSON output: "Infinity" SQL input: "-inf" JSON output: "-Infinity" SQL input: "NaN" JSON output: "NaN"
STRING	string Encoded as a string, escaped according to the JSON standard. Specifically, ", \, and the control characters from U+0000 to U+001F are escaped.	SQL input: "abc" JSON output: "abc" SQL input: "\"abc\"" JSON output: "\"abc\""
BYTES	string Uses RFC 4648 Base64 data encoding.	SQL input: b"Google" JSON output: "R29vZ2xl"
DATE	string	SQL input: DATE '2017-03-06' JSON output: "2017-03-06"
TIMESTAMP	string Encoded as ISO 8601 date and time, where T separates the date and time and Z (Zulu/UTC) represents the time zone.	SQL input: TIMESTAMP '2017-03-06 12:34:56.789012' JSON output: "2017-03-06T12:34:56.789012Z"
DATETIME	string Encoded as ISO 8601 date and time, where T separates the date and time.	SQL input: DATETIME '2017-03-06 12:34:56.789012' JSON output: "2017-03-06T12:34:56.789012"
TIME	string Encoded as ISO 8601 time.	SQL input: TIME '12:34:56.789012' JSON output: "12:34:56.789012"
JSON	data of the input JSON	SQL input: JSON '{"item": "pen", "price": 10}' JSON output: {"item":"pen", "price":10} SQL input:[1, 2, 3] JSON output:[1, 2, 3]
ARRAY	array Can contain zero or more elements.	SQL input: ["red", "blue", "green"] JSON output: ["red","blue","green"] SQL input:[1, 2, 3] JSON output:[1,2,3]
STRUCT	object The object can contain zero or more key/value pairs. Each value is formatted according to its type. For TO_JSON, a field is included in the output string and any duplicates of this field are omitted. For TO_JSON_STRING, a field and any duplicates of this field are included in the output string. Anonymous fields are represented with "". Invalid UTF-8 field names might result in unparseable JSON. String values are escaped according to the JSON standard. Specifically, ", \, and the control characters from U+0000 to U+001F are escaped.	SQL input: STRUCT(12 AS purchases, TRUE AS inStock) JSON output: {"inStock": true,"purchases":12}

JSONPath format

With the JSONPath format, you can identify the values you want to obtain from a JSON-formatted string. The JSONPath format supports these operators:

Operator	Description	Examples
$	Root object or element. The JSONPath format must start with this operator, which refers to the outermost level of the JSON-formatted string.	JSON-formatted string: '{"class" : {"students" : [{"name" : "Jane"}]}}' JSON path: "$" JSON result: {"class":{"students":[{"name":"Jane"}]}}
.	Child operator. You can identify child values using dot-notation.	JSON-formatted string: '{"class" : {"students" : [{"name" : "Jane"}]}}' JSON path: "$.class.students" JSON result: [{"name":"Jane"}]
[]	Subscript operator. If the JSON object is an array, you can use brackets to specify the array index.	JSON-formatted string: '{"class" : {"students" : [{"name" : "Jane"}]}}' JSON path: "$.class.students[0]" JSON result: {"name":"Jane"}

If a key in a JSON functions contains a JSON format operator, refer to each JSON function for how to escape them.

A JSON function returns NULL if the JSONPath format does not match a value in a JSON-formatted string. If the selected value for a scalar function is not scalar, such as an object or an array, the function returns NULL. If the JSONPath format is invalid, an error is produced.