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Python 3.10 is now generally available.

google.appengine.api.validation.Type

Verifies property is of expected type.

Inherits From: Validator, expected_type

Can optionally convert value if it is not of the expected type.

It is possible to specify a required field of a specific type in shorthand by merely providing the type. This method is slightly less efficient than providing an explicit type but is not significant unless parsing a large amount of information:

  class Person(Validated):
    ATTRIBUTES = {'name': unicode,
                  'age': int,
                  }

However, in most instances it is best to use the type constants:

  class Person(Validated):
    ATTRIBUTES = {'name': TypeUnicode,
                  'age': TypeInt,
                  }

expected_type Type that attribute should validate against.
convert Cause conversion if value is not the right type. Conversion is done by calling the constructor of the type with the value as its first parameter.
default Default assignment is made during initialization and will not pass through validation.

Child Classes

class expected_type

Methods

CheckFieldInitialized

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Check for missing fields or conflicts between fields.

Default behavior performs a simple None-check, but this can be overridden. If the intent is to allow optional fields, then use the Optional validator instead.

Args
value Value to validate.
key Name of the field being validated.
obj The object to validate against.

Raises
ValidationError When there are missing or conflicting fields.

GetWarnings

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Return any warnings on this attribute.

Validates the value with an eye towards things that aren't fatal problems.

Args
value Value to validate.
key Name of the field being validated.
obj The object to validate against.

Returns
A list of tuples (context, warning) where

  • Context is the field (or dotted field path, if a sub-field)
  • Warning is the string warning text

ToValue

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Convert value to a simplified collection or basic type.

Subclasses of Validator should override this method when the dumped representation of value is not a simple <type>(value) (e.g., a regex).

Args
value An object of the same type that was returned from Validate().

Returns
An instance of a builtin type (e.g., int, str, dict, etc). By default it returns value unmodified.

Validate

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Validate that value has the correct type.

Args
value Value to validate.
key Name of the field being validated.

Returns
value if value is of the correct type. value is coverted to the correct type if the Validator is configured to do so.

Raises
ValidationError If value is not of the right type and the validator is either configured not to convert or cannot convert.

__call__

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Main interface to validator is call mechanism.