Cloud Firestore Data model

Cloud Firestore is a NoSQL, document-oriented database. Unlike a SQL database, there are no tables or rows. Instead, you store data in documents , which are organized into collections .

Each document contains a set of key-value pairs. Cloud Firestore is optimized for storing large collections of small documents.

All documents must be stored in collections. Documents can contain subcollections and nested objects, both of which can include primitive fields like strings or complex objects like lists.

Collections and documents are created implicitly in Cloud Firestore . Simply assign data to a document within a collection. If either the collection or document does not exist, Cloud Firestore creates it.

Documents

In Cloud Firestore , the unit of storage is the document. A document is a lightweight record that contains fields, which map to values. Each document is identified by a name.

A document representing a user alovelace might look like this:

• class alovelace

  first : "Ada"
last : "Lovelace"
born : 1815
  

Complex, nested objects in a document are called maps. For example, you could structure the user's name from the example above with a map, like this:

• class alovelace

  name :
first : "Ada"
last : "Lovelace"
born : 1815
  

You may notice that documents look a lot like JSON. In fact, they basically are. There are some differences (for example, documents support extra data types and are limited in size to 1 MB), but in general, you can treat documents as lightweight JSON records.

Collections

Documents live in collections, which are simply containers for documents. For example, you could have a users collection to contain your various users, each represented by a document:

• collections_bookmark users

  • class alovelace

    first : "Ada"
last : "Lovelace"
born : 1815
    

  • class aturing

    first : "Alan"
last : "Turing"
born : 1912
    

Cloud Firestore is schemaless, so you have complete freedom over what fields you put in each document and what data types you store in those fields. Documents within the same collection can all contain different fields or store different types of data in those fields. However, it's a good idea to use the same fields and data types across multiple documents, so that you can query the documents more easily.

A collection contains documents and nothing else. It can't directly contain raw fields with values, and it can't contain other collections. (See Hierarchical Data for an explanation of how to structure more complex data in Cloud Firestore .)

The names of documents within a collection are unique. You can provide your own keys, such as user IDs, or you can let Cloud Firestore create random IDs for you automatically.

You do not need to "create" or "delete" collections. After you create the first document in a collection, the collection exists. If you delete all of the documents in a collection, it no longer exists.

References

Every document in Cloud Firestore is uniquely identified by its location within the database. The previous example showed a document alovelace within the collection users . To refer to this location in your code, you can create a reference to it.

 import 
  
 { 
  
 doc 
  
 } 
  
 from 
  
 "firebase/firestore" 
 ; 
 const 
  
 alovelaceDocumentRef 
  
 = 
  
 doc 
 ( 
 db 
 , 
  
 'users' 
 , 
  
 'alovelace' 
 ); 
 
  doc_reference 
 . 
 js 
 
 

 var 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 'users' 
 ). 
 doc 
 ( 
 'alovelace' 
 ); 
 
  test 
 . 
 firestore 
 . 
 js 
 
 

 let 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 "users" 
 ). 
 document 
 ( 
 "alovelace" 
 ) 
 
  ViewController 
 . 
 swift 
 
 

 FIRDocumentReference 
  
 * 
 alovelaceDocumentRef 
  
 = 
  
 [[ 
 self 
 . 
 db 
  
 collectionWithPath 
 : 
 @"users" 
 ] 
  
 documentWithPath 
 : 
 @"alovelace" 
 ]; 
 
  ViewController 
 . 
 m 
 
 

 val 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 "users" 
 ). 
 document 
 ( 
 "alovelace" 
 ) 
 
  DocSnippets 
 . 
 kt 
 
 

 DocumentReference 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 "users" 
 ). 
 document 
 ( 
 "alovelace" 
 ); 
 
  DocSnippets 
 . 
 java 
 
 

 final 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 "users" 
 ). 
 doc 
 ( 
 "alovelace" 
 ); 
 
  firestore 
 . 
 dart 
 
 

  // Reference to a document with id "alovelace" in the collection "users" 
 DocumentReference 
  
 document 
  
 = 
  
 db 
 . 
 collection 
 ( 
 "users" 
 ). 
 document 
 ( 
 "alovelace" 
 ); 
 
  References 
 . 
 java 
 
 
 

  a_lovelace_ref 
 = 
 db 
 . 
 collection 
 ( 
 "users" 
 ) 
 . 
 document 
 ( 
 "alovelace" 
 ) 
 
  snippets 
 . 
 py 
 
 
 

  a_lovelace_ref 
 = 
 db 
 . 
 collection 
 ( 
 "users" 
 ) 
 . 
 document 
 ( 
 "alovelace" 
 ) 
 
  snippets 
 . 
 py 
 
 
 

 DocumentReference 
  
 alovelace_document_reference 
  
 = 
  
 db 
 - 
> Collection 
 ( 
 "users" 
 ). 
 Document 
 ( 
 "alovelace" 
 ); 
 
  snippets 
 . 
 cpp 
 
 

  const 
  
 alovelaceDocumentRef 
  
 = 
  
 db 
 . 
 collection 
 ( 
 'users' 
 ). 
 doc 
 ( 
 'alovelace' 
 ); 
 
  index 
 . 
 js 
 
 
 

  import 
  
 ( 
  
 "cloud.google.com/go/firestore" 
 ) 
 func 
  
 createDocReference 
 ( 
 client 
  
 * 
 firestore 
 . 
 Client 
 ) 
  
 { 
  
 alovelaceRef 
  
 := 
  
 client 
 . 
 Collection 
 ( 
 "users" 
 ). 
 Doc 
 ( 
 "alovelace" 
 ) 
  
 _ 
  
 = 
  
 alovelaceRef 
 } 
 
  retrieve_data_reference_document 
 . 
 go 
 
 
 

  $document = $db->collection('samples/php/users')->document('alovelace'); 
 data_reference_document.php