Firestore for Rust

Library provides a simple API for Google Firestore based on the official gRPC API:

• Create or update documents using Rust structures and Serde;
• Support for:
  • Querying/streaming docs/objects;
  • Listing documents/objects (and auto pages scrolling support);
  • Listening changes from Firestore;
  • Transactions;
  • Aggregated Queries;
  • Streaming batch writes with automatic throttling to avoid time limits from Firestore;
  • K-nearest neighbor (KNN) vector search;
  • Explaining queries;
• Fluent high-level and strongly typed API;
• Full async based on Tokio runtime;
• Macro that helps you use JSON paths as references to your structure fields;
• Implements own Serde serializer to Firestore protobuf values;
• Support for multiple database IDs
• Supports for extended datatypes:
  • Firestore timestamp with #[serde(with)] and a specialized structure
  • Lat/Lng
  • References
• Caching support for collections and documents:
  • In-memory cache;
  • Persistent cache;
• Google client based on gcloud-sdk library that automatically detects GCE environment or application default accounts for local development;

Quick start

Cargo.toml:

[dependencies]
firestore = "0.44"

Examples

All examples available in the examples directory.

To run an example with environment variables:

PROJECT_ID=<your-google-project-id> cargo run --example crud

Firestore database client instance and lifecycle

To create a new instance of Firestore client you need to provide at least a GCP project ID. It is not recommended creating a new client for each request, so it is recommended to create a client once and reuse it whenever possible. Cloning instances is much cheaper than creating a new one.

The client is created using the Firestore::new method:

use firestore::*;

// Create an instance
let db = FirestoreDb::new( & config_env_var("PROJECT_ID") ? ).await?;

This is the recommended way to create a new instance of the client, since it automatically detects the environment and uses credentials, service accounts, Workload Identity on GCP, etc. Look at the section below Google authentication for more details.

In cases if you need to create a new instance explicitly specifying a key file, you can use:

FirestoreDb::with_options_service_account_key_file(
  FirestoreDbOptions::new(config_env_var("PROJECT_ID") ?.to_string()),
  "/tmp/key.json".into()
).await?

or if you need even more flexibility you can use a preconfigured token source and scopes with:

FirestoreDb::with_options_token_source(
  FirestoreDbOptions::new(config_env_var("PROJECT_ID") ?.to_string()),
  gcloud_sdk::GCP_DEFAULT_SCOPES.clone(),
  gcloud_sdk::TokenSourceType::File("/tmp/key.json".into())
).await?

Firebase supports multiple databases per project now, so you can specify the database ID in the options:

FirestoreDb::with_options(
  FirestoreDbOptions::new("your-project-id".to_string())
    .with_database_id("your-database-id".to_string())
  )
.await?

Fluent API

The library provides two APIs:

• Fluent API: To simplify development and developer experience the library provides more high level API starting with v0.12.x. This is the recommended API for all applications to use.
• Classic and low level API: the API existing before 0.12 is still available and not deprecated, so it is fine to continue to use when needed. Furthermore the Fluent API is based on the same classic API and generally speaking are something like smart and convenient constructors. The API can be changed with introducing incompatible changes so it is not recommended to use in long term.

use firestore::*;

const TEST_COLLECTION_NAME: &'static str = "test";

let my_struct = MyTestStructure {
  some_id: "test-1".to_string(),
  some_string: "Test".to_string(),
  one_more_string: "Test2".to_string(),
  some_num: 42,
};

// Create
let object_returned: MyTestStructure = db.fluent()
  .insert()
  .into(TEST_COLLECTION_NAME)
  .document_id( & my_struct.some_id)
  .object( & my_struct)
  .execute()
  .await?;

// Update or Create 
// (Firestore supports creating documents with update if you provide the document ID).
let object_updated: MyTestStructure = db.fluent()
  .update()
  .fields(paths!(MyTestStructure::{some_num, one_more_string}))
  .in_col(TEST_COLLECTION_NAME)
  .document_id( & my_struct.some_id)
  .object( & MyTestStructure {
      some_num: my_struct.some_num + 1,
      one_more_string: "updated-value".to_string(),
        ..my_struct.clone()
   })
  .execute()
  .await?;

// Get object by id
let find_it_again: Option<MyTestStructure> = db.fluent()
  .select()
  .by_id_in(TEST_COLLECTION_NAME)
  .obj()
  .one( & my_struct.some_id)
  .await?;

// Delete data
db.fluent()
  .delete()
  .from(TEST_COLLECTION_NAME)
  .document_id( & my_struct.some_id)
  .execute()
  .await?;

Querying

The library supports rich querying API with filters, ordering, pagination, etc.

// Query as a stream our data
let object_stream: BoxStream<FirestoreResult<MyTestStructure> > = db.fluent()
  .select()
  .fields(paths!(MyTestStructure::{some_id, some_num, some_string, one_more_string, created_at})) // Optionally select the fields needed
  .from(TEST_COLLECTION_NAME)
  .filter( | q| { // Fluent filter API example
      q.for_all([
        q.field(path!(MyTestStructure::some_num)).is_not_null(),
        q.field(path!(MyTestStructure::some_string)).eq("Test"),
        // Sometimes you have optional filters
        Some("Test2")
          .and_then( | value | q.field(path ! (MyTestStructure::one_more_string)).eq(value)),        
      ])
  })
  .order_by([(
    path!(MyTestStructure::some_num),
    FirestoreQueryDirection::Descending,
  )])
  .obj() // Reading documents as structures using Serde gRPC deserializer
  .stream_query_with_errors()
  .await?;

let as_vec: Vec<MyTestStructure> = object_stream.try_collect().await?;
println!("{:?}", as_vec);

Use:

• q.for_all for AND conditions
• q.for_any for OR conditions (Firestore has just recently added support for OR conditions)

You can nest q.for_all/q.for_any.

Get and batch get support

let find_it_again: Option<MyTestStructure> = db.fluent()
  .select()
  .by_id_in(TEST_COLLECTION_NAME)
  .obj()
  .one( & my_struct.some_id)
  .await?;

let object_stream: BoxStream<(String, Option<MyTestStructure>) > = db.fluent()
  .select()
  .by_id_in(TEST_COLLECTION_NAME)
  .obj()
  .batch(vec!["test-0", "test-5"])
  .await?;

Timestamps support

By default, the types such as DateTime serializes as a string to Firestore (while deserialization works from Timestamps and Strings).

To change this behaviour and support Firestore timestamps on database level there are two options:

• #[serde(with)] and attributes:

#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure {
    #[serde(with = "firestore::serialize_as_timestamp")]
    created_at: DateTime<Utc>,

    #[serde(default)]
    #[serde(with = "firestore::serialize_as_optional_timestamp")]
    updated_at: Option<DateTime<Utc>>,
}

• using a type FirestoreTimestamp:

#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure {
    created_at: firestore::FirestoreTimestamp,
    updated_at: Option<firestore::FirestoreTimestamp>
}

This will change it only for firestore serialization, but it still serializes as string to JSON (so you can reuse the same model for JSON and Firestore).

In your queries you need to use the wrapping class firestore::FirestoreTimestamp, for example:

   q.field(path!(MyTestStructure::created_at)).less_than_or_equal(firestore::FirestoreTimestamp(Utc::now()))

Nested collections

You can work with nested collections specifying path/location to a parent for documents:

// Creating a parent doc
db.fluent()
  .insert()
  .into(TEST_PARENT_COLLECTION_NAME)
  .document_id(&parent_struct.some_id)
  .object(&parent_struct)
  .execute()
  .await?;

// The doc path where we store our children
let parent_path = db.parent_path(TEST_PARENT_COLLECTION_NAME, parent_struct.some_id)?;

// Create a child doc
db.fluent()
  .insert()
  .into(TEST_CHILD_COLLECTION_NAME)
  .document_id(&child_struct.some_id)
  .parent(&parent_path)
  .object(&child_struct)
  .execute()
  .await?;

// Listing children
println!("Listing all children");

let objs_stream: BoxStream<MyChildStructure> = db.fluent()
  .list()
  .from(TEST_CHILD_COLLECTION_NAME)
  .parent( & parent_path)
  .obj()
  .stream_all()
  .await?;

Complete example available here.

You can nest multiple levels of collections using at():

let parent_path =
db.parent_path(TEST_PARENT_COLLECTION_NAME, "parent-id")?
  .at(TEST_CHILD_COLLECTION_NAME, "child-id")?
  .at(TEST_GRANDCHILD_COLLECTION_NAME, "grand-child-id")?;

Transactions

To manage transactions manually you can use db.begin_transaction(), and then the Fluent API to add the operations needed in the transaction.

let mut transaction = db.begin_transaction().await?;

db.fluent()
  .update()
  .fields(paths!(MyTestStructure::{
       some_string
     }))
  .in_col(TEST_COLLECTION_NAME)
  .document_id("test-0")
  .object( & MyTestStructure {
    some_id: format!("test-0"),
    some_string: "UpdatedTest".to_string(),
  })
  .add_to_transaction( & mut transaction) ?;

db.fluent()
  .delete()
  .from(TEST_COLLECTION_NAME)
  .document_id("test-5")
  .add_to_transaction( & mut transaction) ?;

transaction.commit().await?;

You may also execute transactions that automatically retry with exponential backoff using run_transaction.

    db.run_transaction( | db, transaction| {
      Box::pin(async move {
      let mut test_structure: MyTestStructure = db
        .fluent()
        .select()
        .by_id_in(TEST_COLLECTION_NAME)
        .obj()
        .one(TEST_DOCUMENT_ID)
        .await?
        .expect("Missing document");

      // Perform some kind of operation that depends on the state of the document
      test_structure.test_string += "a";

      db.fluent()
        .update()
        .fields(paths!(MyTestStructure::{
          test_string
         }))
        .in_col(TEST_COLLECTION_NAME)
        .document_id(TEST_DOCUMENT_ID)
        .object(&test_structure)
        .add_to_transaction(transaction) ?;

        Ok(())
      })
})
  .await?;

See the complete example available here.

Please note that Firestore doesn't support creating documents in the transactions (generating document IDs automatically), so you need to use update() to implicitly create documents and specifying your own IDs.

Reading Firestore document metadata as struct fields

Firestore provides additional generated fields for each of document you create:

• _firestore_id: Generated document ID (when it is not specified from the client);
• _firestore_created: The time at which the document was created;
• _firestore_updated: The time at which the document was last changed;

To be able to read them the library makes them available as system fields for the Serde deserializer with reserved names, so you can specify them in your structures as:

#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure {
    #[serde(alias = "_firestore_id")]
    id: Option<String>,
    #[serde(alias = "_firestore_created")]
    created_at: Option<DateTime<Utc>>,
    #[serde(alias = "_firestore_updated")]
    updated_at: Option<DateTime<Utc>>,
    some_string: String,
    one_more_string: String,
    some_num: u64,
}

Complete example available here.

Working on dynamic/document level

Sometimes having static structure may restrict you from working with dynamic data, so there is a way to use Fluent API to work with documents without introducing structures at all.

let object_returned = db
.fluent()
.insert()
.into(TEST_COLLECTION_NAME)
.document_id("test-1")
.document(FirestoreDb::serialize_map_to_doc("",
    [
      ("some_id", "test-id".into()),
      ("some_string", "test-value".into()),
      ("some_num", 42.into()),
      (
      "embedded_obj",
        FirestoreValue::from_map([
          ("inner_some_id", "inner-id-value".into()),
          ("inner_some_string", "inner-some-value".into()),
        ]),
      ),
      ("created_at", FirestoreTimestamp(Utc::now()).into()),
    ])?
)
.execute()
.await?;

Full example available here.

Document transformations

The library supports server side document transformations in transactions and batch writes:

// Only transformation
db.fluent()
.update()
.in_col(TEST_COLLECTION_NAME)
.document_id("test-4")
.transforms(|t| { // Transformations
    t.fields([
      t.field(path!(MyTestStructure::some_num)).increment(10),
      t.field(path!(MyTestStructure::some_array)).append_missing_elements([4, 5]),
      t.field(path!(MyTestStructure::some_array)).remove_all_from_array([3]),
    ])
})
.only_transform()
.add_to_transaction( & mut transaction) ?; // or add_to_batch

// Update and transform (in this order and atomically):
db.fluent()
.update()
.in_col(TEST_COLLECTION_NAME)
.document_id("test-5")
.object(&my_obj) // Updating the objects with the fields here
.transforms(|t| { // Transformations after the update
    t.fields([
      t.field(path!(MyTestStructure::some_num)).increment(10),
    ])
})
.add_to_transaction(&mut transaction) ?; // or add_to_batch

Listening the document changes on Firestore

To help to work with asynchronous event listener the library supports high level API for listening the events from Firestore on a separate thread:

The listener implementation needs to be provided with a storage for the last received token for specified targets to be able to resume listening the changes from the last handled token and to avoid receiving all previous changes.

The library provides basic implementations for storing the tokens but you can implement your own more sophisticated storage if needed:

• FirestoreTempFilesListenStateStorage - resume tokens stored as temporary files on local FS;
• FirestoreMemListenStateStorage - in memory storage backed by HashMap (with this implementation if you restart your app, you will receive all notifications again);

let mut listener = db.create_listener(
    FirestoreTempFilesListenStateStorage::new() // or FirestoreMemListenStateStorage or your own implementation 
).await?;

// Adding query listener
db.fluent()
.select()
.from(TEST_COLLECTION_NAME)
.listen()
.add_target(TEST_TARGET_ID_BY_QUERY, &mut listener) ?;

// Adding docs listener by IDs
db.fluent()
.select()
.by_id_in(TEST_COLLECTION_NAME)
.batch_listen([doc_id1, doc_id2])
.add_target(TEST_TARGET_ID_BY_DOC_IDS, &mut listener) ?;

listener
.start( | event| async move {
    match event {
        FirestoreListenEvent::DocumentChange( ref doc_change) => {
            println ! ("Doc changed: {:?}", doc_change);
            
            if let Some(doc) = & doc_change.document {
              let obj: MyTestStructure =
              FirestoreDb::deserialize_doc_to::<MyTestStructure > (doc)
              .expect("Deserialized object");
              println ! ("As object: {:?}", obj);
            }
        }
        _ => {
          println ! ("Received a listen response event to handle: {:?}", event);
        }
    }

  Ok(())
})
.await?;

// Wait some events like Ctrl-C, signals, etc
// <put-your-implementation-for-wait-here>

// and then shutdown
listener.shutdown().await?;

See complete example in examples directory.

Explicit null value serialization

By default, all Option<> serialized as absent fields, which is convenient for many cases. However sometimes you need to have explicit nulls.

To help with that there are additional attributes implemented for serde(with):

• For any type:

#[serde(default)]
#[serde(with = "firestore::serialize_as_null")]
test_null: Option<String>,

• For Firestore timestamps attribute:

#[serde(default)]
#[serde(with = "firestore::serialize_as_null_timestamp")]
test_null: Option<DateTime<Utc> >,

Select aggregate functions

The library supports the aggregation functions for the queries:

db.fluent()
  .select()
  .from(TEST_COLLECTION_NAME)
  .aggregate(|a| a.fields([a.field(path!(MyAggTestStructure::counter)).count()]))
  .obj()
  .query()
  .await?;

Update/delete preconditions

The library supports the preconditions:

  .precondition(FirestoreWritePrecondition::Exists(true))

Explaining the query

The library supports the query explanation:

db.fluent()
  .select()
  .from(TEST_COLLECTION_NAME)
  .explain()
  // or use explain_with_options if you want to provide additional options like analyze which run query to gather additional statistics 
  // .explain_with_options(FirestoreExplainOptions::new().with_analyze(true))
  .stream_query_with_metadata()
  .await?;

Google authentication

Looks for credentials in the following places, preferring the first location found:

• A JSON file whose path is specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable.
• A JSON file in a location known to the gcloud command-line tool using gcloud auth application-default login.
• On Google Compute Engine, it fetches credentials from the metadata server.

Local development

Don't confuse gcloud auth login with gcloud auth application-default login for local development, since the first authorize only gcloud tool to access the Cloud Platform.

The latter obtains user access credentials via a web flow and puts them in the well-known location for Application Default Credentials (ADC). This command is useful when you are developing code that would normally use a service account but need to run the code in a local development environment where it's easier to provide user credentials. So to work for local development you need to use gcloud auth application-default login.

Working with docker images

When you design your Dockerfile make sure you either installed Root CA certificates or use base images that already include them. If you don't have certs installed you usually observe the errors such as:

SystemError(FirestoreSystemError { public: FirestoreErrorPublicGenericDetails { code: "GrpcStatus(tonic::transport::Error(Transport, hyper::Error(Connect, Custom { kind: InvalidData, error: InvalidCertificateData(\"invalid peer certificate: UnknownIssuer\") })))" }, message: "GCloud system error: Tonic/gRPC error: transport error" })

For example for Debian based images, this usually can be fixed using this package:

RUN apt-get install -y ca-certificates

Also, I recommend considering using Google Distroless images since they are secure, already include Root CA certs, and are optimised for size.

Firestore emulator

To work with the Google Firestore emulator you can use the environment variable:

export FIRESTORE_EMULATOR_HOST="localhost:8080"

or specify it as an option using FirestoreDb::with_options()

Caching

The library supports caching for collections and documents. Caching is leveraging the Firestore listener to update the cache when the document is changed, that means the updates will be propagated across distributed instances automatically for you.

This is useful to avoid reading and paying for the same documents from Firestore multiple times. Especially for some data such as dictionaries, configuration, and other information that is not changed frequently. In fact, this may be really helpful to reduce both costs and latency in your applications.

Caching works on the document level. The cache will be used for the following operations:

• Reading documents by IDs (get and batch get);
• Listing all documents in a collection;
• Partial support for querying documents in a collection:
  • Filtering;
  • Ordering;
  • Paging/Cursors;

(Caching other operations may be extended in the future).

The library provides two implementations of the cache:

• In-memory cache, implemented using moka cache library;
• Persistent cache, implemented using redb and protobuf;

Caching is opt-in and you need to enable it when needed using cargo features:

• caching-memory for in-memory cache;
• caching-persistent for persistent/disk-backed cache;

Load modes

Caching supports different init/load modes:

• PreloadNone: Don't preload anything, just fill in the cache while working;
• PreloadAllDocs: Preload all documents from the collection to the cache;
• PreloadAllIfEmpty: Preload all documents from the collection to the cache only if the cache is empty (this is only useful for persistent cache, for memory cache it is the same as PreloadAllDocs);

How a cache is updated

Update cache is done in the following cases:

• When you read a document through a cache by ID and it is not found in the cache, it will be loaded from Firestore and cached;
• Firestore listener will update the cache when it receives a notification about the document change (externally or from your app);
• Using Preloads at the startup time;

Usage

// Create an instance
let db = FirestoreDb::new( &config_env_var("PROJECT_ID") ? ).await?;

const TEST_COLLECTION_NAME: &'static str = "test-caching";

// Create a cache instance that also creates an internal Firestore listener
let mut cache = FirestoreCache::new(
"example-mem-cache".into(),
&db,
FirestoreMemoryCacheBackend::new(
  FirestoreCacheConfiguration::new().add_collection_config(
    &db,
    FirestoreCacheCollectionConfiguration::new(
      TEST_COLLECTION_NAME,
      FirestoreListenerTarget::new(1000),
      FirestoreCacheCollectionLoadMode::PreloadNone,
    )
  ),
)?,
  FirestoreMemListenStateStorage::new(),
)
.await?;

// Load and init cache
cache.load().await?; // Required even if you don't preload anything

// Read a document through the cache. If it is not found in the cache, it will be loaded from Firestore and cached.
let my_struct0: Option<MyTestStructure> = db.read_through_cache(&cache)
  .fluent()
  .select()
  .by_id_in(TEST_COLLECTION_NAME)
  .obj()
  .one("test-1")
  .await?;

// Read a document only from the cache. If it is not found in the cache, it will return None.
let my_struct0: Option<MyTestStructure> = db.read_cached_only(&cache)
  .fluent()
  .select()
  .by_id_in(TEST_COLLECTION_NAME)
  .obj()
  .one("test-1")
  .await?;

Full examples available here and here.

TLS related features

Cargo provides support for different TLS features for dependencies:

• tls-roots: default feature to support native TLS roots
• tls-webpki-roots: feature to switch to webpki crate roots

How this library is tested

There are integration tests in the tests directory that runs for every commit against the real Firestore instance allocated for testing purposes. Be aware not to introduce huge document reads/updates and collection isolation from other tests.

Licence

Apache Software License (ASL)

Author

Abdulla Abdurakhmanov