google.golang.org/cloud/firestore (go): Package firestore provides a client for reading and writing to a Cloud Firestore database.  See https://cloud.google.com/firestore/docs for an introduction to Cloud Firestore and additional help on using the Firestore API.  See https://godoc.org/cloud.google.com/go for authentication, timeouts, connection pooling and similar aspects of this package.  Note: you can't use both Cloud Firestore and Cloud Datastore in the same project.  To start working with this package, create a client with a project ID:  In Firestore, documents are sets of key-value pairs, and collections are groups of documents. A Firestore database consists of a hierarchy of alternating collections and documents, referred to by slash-separated paths like "States/California/Cities/SanFrancisco".  This client is built around references to collections and documents. CollectionRefs and DocumentRefs are lightweight values that refer to the corresponding database entities. Creating a ref does not involve any network traffic.  Use DocumentRef.Get to read a document. The result is a DocumentSnapshot. Call its Data method to obtain the entire document contents as a map.  You can also obtain a single field with DataAt, or extract the data into a struct with DataTo. With the type definition  we can extract the document's data into a value of type State:  Note that this client supports struct tags beginning with "firestore:" that work like the tags of the encoding/json package, letting you rename fields, ignore them, or omit their values when empty.  To retrieve multiple documents from their references in a single call, use Client.GetAll.  For writing individual documents, use the methods on DocumentReference. Create creates a new document.  The first return value is a WriteResult, which contains the time at which the document was updated.  Create fails if the document exists. Another method, Set, either replaces an existing document or creates a new one.  To update some fields of an existing document, use Update. It takes a list of paths to update and their corresponding values.  Use DocumentRef.Delete to delete a document.  You can condition Deletes or Updates on when a document was last changed. Specify these preconditions as an option to a Delete or Update method. The check and the write happen atomically with a single RPC.  Here we update a doc only if it hasn't changed since we read it. You could also do this with a transaction.  To perform multiple writes at once, use a WriteBatch. Its methods chain for convenience.  WriteBatch.Commit sends the collected writes to the server, where they happen atomically.  You can use SQL to select documents from a collection. Begin with the collection, and build up a query using Select, Where and other methods of Query.  Supported operators include `<`, `<=`, `>`, `>=`, `==`, and 'array-contains'.  Call the Query's Documents method to get an iterator, and use it like the other Google Cloud Client iterators.  To get all the documents in a collection, you can use the collection itself as a query.  Use a transaction to execute reads and writes atomically. All reads must happen before any writes. Transaction creation, commit, rollback and retry are handled for you by the Client.RunTransaction method; just provide a function and use the read and write methods of the Transaction passed to it.
Keywords: cloud-bigquery|cloud-datastore|cloud-pubsub|cloud-storage|go|golang|google-cloud