FieldValue
Sentinel values that can be used when writing documents with set(), create() or update().
Methods
arrayRemove
arrayRemove(...elements) returns FieldValue
Returns a special value that can be used with set(), create() or update() that tells the server to remove the given elements from any array value that already exists on the server. All instances of each element specified will be removed from the array. If the field being modified is not already an array it will be overwritten with an empty array.
Parameter |
|
---|---|
elements |
any type The elements to remove from the array. Value may be repeated. |
- Returns
-
The FieldValue sentinel for use in a call to set(), create() or update().
Example
let documentRef = firestore.doc('col/doc');
documentRef.update(
'array', Firestore.FieldValue.arrayRemove('foo')
).then(() => {
return documentRef.get();
}).then(doc => {
// doc.get('array') no longer contains field 'foo'
});
arrayUnion
arrayUnion(...elements) returns FieldValue
Returns a special value that can be used with set(), create() or update() that tells the server to union the given elements with any array value that already exists on the server. Each specified element that doesn't already exist in the array will be added to the end. If the field being modified is not already an array it will be overwritten with an array containing exactly the specified elements.
Parameter |
|
---|---|
elements |
any type The elements to union into the array. Value may be repeated. |
- Returns
-
The FieldValue sentinel for use in a call to set(), create() or update().
Example
let documentRef = firestore.doc('col/doc');
documentRef.update(
'array', Firestore.FieldValue.arrayUnion('foo')
).then(() => {
return documentRef.get();
}).then(doc => {
// doc.get('array') contains field 'foo'
});
delete
delete() returns FieldValue
Returns a sentinel for use with update() or set() with {merge:true} to mark a field for deletion.
- Returns
-
The sentinel value to use in your objects.
Example
let documentRef = firestore.doc('col/doc');
let data = { a: 'b', c: 'd' };
documentRef.set(data).then(() => {
return documentRef.update({a: Firestore.FieldValue.delete()});
}).then(() => {
// Document now only contains { c: 'd' }
});
increment
increment(n) returns FieldValue
Returns a special value that can be used with set(), create() or update() that tells the server to increment the the field's current value by the given value.
If either current field value or the operand uses floating point precision, both values will be interpreted as floating point numbers and all arithmetic will follow IEEE 754 semantics. Otherwise, integer precision is kept and the result is capped between -2^63 and 2^63-1.
If the current field value is not of type 'number', or if the field does not yet exist, the transformation will set the field to the given value.
Parameter |
|
---|---|
n |
number The value to increment by. |
- Returns
-
The FieldValue sentinel for use in a call to set(), create() or update().
Example
let documentRef = firestore.doc('col/doc');
documentRef.update(
'counter', Firestore.FieldValue.increment(1)
).then(() => {
return documentRef.get();
}).then(doc => {
// doc.get('counter') was incremented
});
serverTimestamp
serverTimestamp() returns FieldValue
Returns a sentinel used with set(), create() or update() to include a server-generated timestamp in the written data.
- Returns
-
The FieldValue sentinel for use in a call to set(), create() or update().
Example
let documentRef = firestore.doc('col/doc');
documentRef.set({
time: Firestore.FieldValue.serverTimestamp()
}).then(() => {
return documentRef.get();
}).then(doc => {
console.log(`Server time set to ${doc.get('time')}`);
});
isEqual
isEqual(other) returns boolean
Returns true if this FieldValue
is equal to the provided value.
Parameter |
|
---|---|
other |
any type The value to compare against. |
- Returns
-
boolean
true if this
FieldValue
is equal to the provided value.