firestore-facade

Firestore Façade

A clean, strongly-typed, zero-dependency API for Firestore Typescript projects.

NOTE: This project is still in its infancy, and probably not ready for consumption just yet

Motivation

• Reduce boilerplate code and improve readability
• Provide strict typing on collection methods like set and update
• Provide strict typing on query select statements and their partial response documents

The aim is to keep the API as close to native as possible while providing as much type safety as is still practical. Firestore Façade is a fairly thin wrapper which does not prevent you from using using plain Firestore API methods. For that reason it is also not aiming to cover the full Firestore API surface.

At the moment this library focusses solely on Node.js using the firestore-admin client.

It should be possible to make this compatible with the Cloud Firestore with a small modification, because both are technically the same product.

In the future I would like to add a package addressing the web client and another one specifically for React hooks.

Usage

1. Install

• npm install firestore-facade
• npm install firestore-facade-cli ts-node --save-dev

Or, if you prefer Yarn:

• yarn add firestore-facade
• yarn add firestore-facade-cli ts-node --save-dev

Currently ts-node is required because the generate script tries to resolve the ts-node loader from the environment where you call the command. I hope find a way to make the command self-contained in the future.

2. Configure Document Type Mapping

In your repository, create a configuration file. It can be named anything and placed anywhere. In this file you create a default export object using a root and optionally a sub property.

In the root property, list all the Firestore root collections using the name as key, and apply their document type on a placeholder object as shown below:

export default {
  root: {
    athletes: {} as Athlete,
    sports_events: {} as Event,
  },
  sub: {
    athletes: {
      medals: {} as Medal,
    },
  },
};

Subcollections are defined under sub. Currently one level of nesting is supported.

In this example the collection names in Firestore are snake-cased, but if your names are camel-cased the key names should mirror that.

The empty objects are only there to make the types available at runtime.

@TODO explain in more detail.

3. Generate Facade Factory Function

The next step is to generate the facade code by passing the location of the configuration file to the generate-facade command:

npx generate-facade ./src/my-document-types-config.ts

Or if you use Yarn:

yarn run generate-facade ./src/my-document-types-config.ts

This should create a file named facade.ts containing the facade factory function in the same location as the supplied config file.

Whenever you change something about your collections or their document types, simply re-run this command to update the facade function.

4. Wrap Firestore Instance

Now you can use the facade factory to wrap your instance of the Firestore client.

import { createFacade } from "./facade";

const db = createFacade(firestore);

API

Below is an example showing the different API methods.

You can find the complete source code in the nodejs example package

@TODO document API in detail.

/**
 * Add and set will enforce the exact document type for each collection. Each
 * collection name is a property, so no more use of untyped strings to
 * reference collections.
 */
const ref = await db.athletes.add({
  name: "Joe",
  age: 23,
  skills: { c: true, d: ["one", "two", "three"], tuple: ["foo", 123] },
});

console.log(`Stored new document at collection_a/${ref.id}`);

await db.athletes.set(ref.id, {
  name: "Jane",
  age: 26,
  skills: { c: true, d: ["one", "two", "three"], tuple: ["foo", 456] },
});

/**
 * For the update function all keys, nested field paths and their values are
 * typed.
 *
 * Note that the type allows for arrays and tuples to be set. Mutating their
 * content via a path like "nested.tuple.1" is not allowed. This should be
 * done the Firestore way using FieldValue objects (not supported yet).
 */
await db.athletes.update(ref.id, {
  age: 27,
  "skills.c": true,
  "skills.tuple": ["bar", 890],
  updated_at: serverTimestamp(),
});

const doc = await db.athletes.get(ref.id);

console.log(doc.data);

const { id: eventId } = await db.sports_events.add({
  name: "Olympics",
  year: 2045,
});

/**
 * Subcollections are accessed by passing a parent document id to the sub
 * method. Currently one level of nesting is supported, but more would be
 * possible if required.
 */
await db.athletes.sub(ref.id).medals.add({
  event_id: eventId,
  type: "gold",
});
/**
 * Queries are using a regular Firestore collection reference, so they largely
 * use the official API and parameters to methods like "where" are not typed.
 *
 * The query does use automatic batching to fetch all documents in chunks. An
 * alternative, using generator function, will be available in the future.
 */
const fullDocs = await db.athletes.query((ref) =>
  ref.where("skills.c", "==", true),
);

console.log(`Retrieved ${fullDocs.length} documents`);

/**
 * Perform a query with document field selection. The fields argument is
 * typed, and the response document is typed to only contain the picked
 * properties.
 */
const partialDocs = await db.athletes.queryAndSelect(
  (ref) => ref.where("updated_at", "<", new Date()),
  ["name", "skills"],
);

partialDocs.forEach((doc) => console.log(doc.data.name, doc.data.skills));