Add Data to Cloud Firestore
There are several ways to write data to Cloud Firestore:
- Set the data of a document within a collection, explicitly specifying a document identifier.
- Add a new document to a collection. In this case, Cloud Firestore automatically generates the document identifier.
- Create an empty document with an automatically generated identifier, and assign data to it later.
This guide explains how to use the set, add, or update individual documents in Cloud Firestore. If you want to write data in bulk, see Transactions and Batched Writes.
Set a document
To create or overwrite a single document, use the set() method:
[[[ self . db collectionWithPath :@ "cities" ] documentWithPath :@ "LA" ] setData :@{
@ "name" : @ "Los Angeles" ,
@ "state" : @ "CA" ,
@ "country" : @ "USA"
} completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error writing document: %@" , error );
} else {
NSLog (@ "Document successfully written!" );
}
}];
If the document does not exist, it will be created. If the document does exist, its contents will be overwritten with the newly provided data, unless you specify that the data should be merged into the existing document, as follows:
// if the document already exists
[[[ self . db collectionWithPath :@ "cities" ] documentWithPath :@ "BJ" ]
setData :@{ @ "capital" : @YES }
options :[ FIRSetOptions merge ]
completion :^( NSError * _Nullable error ) {
// ...
}];
If you're not sure whether the document exists, pass the option to merge the new data with any existing document to avoid overwriting entire documents.
Data types
Cloud Firestore lets you write a variety of data types inside a document, including strings, booleans, numbers, dates, null, and nested arrays and objects. Cloud Firestore always stores numbers as doubles, regardless of what type of number you use in your code.
@ "stringExample" : @ "Hello world!" ,
@ "booleanExample" : @YES ,
@ "numberExample" : @ 3.14 ,
@ "dateExample" : [ NSDate date ],
@ "arrayExample" : @[@ 5 , @YES , @ "hello" ],
@ "nullExample" : [ NSNull null ],
@ "objectExample" : @{
@ "a" : @ 5 ,
@ "b" : @{
@ "nested" : @ "foo"
}
}
};
[[[ self . db collectionWithPath :@ "data" ] documentWithPath :@ "one" ] setData : docData
completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error writing document: %@" , error );
} else {
NSLog (@ "Document successfully written!" );
}
}];
Custom objects
Using Java Map objects to represent your documents is often not very convenient, so Cloud Firestore also supports writing your own Java objects with custom classes. Cloud Firestore will internally convert the objects to supported data types.
Using custom classes, you could rewrite the initial example as follows:
Add a document
When you use set() to create a document, you must specify an ID for the document to create. For example:
setData : data ];
But sometimes there isn't a meaningful ID for the document, and it's more convenient to let Cloud Firestore auto-generate an ID for you. You can do this by calling add():
__block FIRDocumentReference * ref =
[[ self . db collectionWithPath :@ "cities" ] addDocumentWithData :@{
@ "name" : @ "Tokyo" ,
@ "country" : @ "Japan"
} completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error adding document: %@" , error );
} else {
NSLog (@ "Document added with ID: %@" , ref . documentID );
}
}];
In some cases, it can be useful to create a document reference with an auto-generated ID, then use the reference later. For this use case, you can call doc():
// later...
[ newCityRef setData :@{ /* ... */ }];
Behind the scenes, .add(...) and .doc().set(...) are completely equivalent, so you can use whichever is more convenient.
Update a document
To update some fields of a document without overwriting the entire document, use the update()method:
[[ self . db collectionWithPath :@ "cities" ] documentWithPath :@ "DC" ];
// Set the "capital" field of the city
[ washingtonRef updateData :@{
@ "capital" : @YES
} completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error updating document: %@" , error );
} else {
NSLog (@ "Document successfully updated" );
}
}];
Update fields in nested objects
If your document contains nested objects, you can use "dot notation" to reference nested fields within the document when you call update():
FIRDocumentReference * frankDocRef =
[[ self . db collectionWithPath :@ "users" ] documentWithPath :@ "frank" ];
[ frankDocRef setData :@{
@ "name" : @ "Frank" ,
@ "favorites" : @{
@ "food" : @ "Pizza" ,
@ "color" : @ "Blue" ,
@ "subject" : @ "recess"
},
@ "age" : @ 12
}];
// To update age and favorite color:
[ frankDocRef updateData :@{
@ "age" : @ 13 ,
@ "favorites.color" : @ "Red" ,
} completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error updating document: %@" , error );
} else {
NSLog (@ "Document successfully updated" );
}
}];
You can also add server timestamps to specific fields in your documents, to track when an update was received by the server:
@ "lastUpdated" : [ FIRFieldValue fieldValueForServerTimestamp ]
} completion :^( NSError * _Nullable error ) {
if ( error != nil ) {
NSLog (@ "Error updating document: %@" , error );
} else {
NSLog (@ "Document successfully updated" );
}
}];