Firebase Firestore

Cloud Firestore (Enterprise edition) - Android Setup Guide (Kotlin)

This guide describes the SDK setup and basic usage patterns for Cloud Firestore (Enterprise edition in Native mode) in an Android app using Kotlin DSL (build.gradle.kts) and Kotlin code.

Prerequisites

IMPORTANT: Before specifically working with Cloud Firestore, make sure to use the skill and reference firebase_basics/references/android_setup to ensure the following is done.

• The Firebase CLI is available and authenticated.

• An Android project exists and is registered with a Firebase Project.

• The Android project has a Firebase config file (google-services.json) and the Google services Gradle plugin (google-services).

1. Provision Firestore

Follow the instructions in firebase_firestore/references/enterprise/provisioning to do the following:

• Provision a Firestore instance (Enterprise edition in Native mode)

• Create or append a firebase.json file

• Create a firestore.rules file

• Create a firestore.indexes.json file

• Deploy database, rules, and indexes

• Run Firestore locally for development and testing

2. Add dependencies to Gradle build files

[!IMPORTANT] [AGENT] RESOLVING THE SDK VERSION DETERMINISTICALLY Never guess or hardcode a memorized out-of-date SDK or plugin version. Before adding dependencies, you MUST query the latest available versions directly from the Google Maven Repository:

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# Find the latest Firebase Android BoM version
curl -s https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-bom/maven-metadata.xml | grep -oE '<latest>[^<]+' | cut -d'>' -f2

# Find the latest firebase-firestore version
curl -s https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-firestore/maven-metadata.xml | grep -oE '<latest>[^<]+' | cut -d'>' -f2

If the dependency is already declared, fetch the exact resolved version currently active in the workspace's build graph:

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./gradlew -q :app:dependencyInsight --dependency firebase-firestore --configuration releaseRuntimeClasspath

In the module (app-level) build.gradle.kts (usually <project>/<app-module>/build.gradle.kts), add the dependency for Cloud Firestore:

dependencies {
    // [AGENT] Fetch the latest resolved version using the Gradle command above
    implementation(platform("com.google.firebase:firebase-bom:<latest_bom_version>"))

    // Add the dependency for the Cloud Firestore library
    // When using the BoM, don't specify versions in Firebase library dependencies
    implementation("com.google.firebase:firebase-firestore")
}

3. Initialize Firestore

Initialize the FirebaseFirestore instance in your ComponentActivity (Jetpack Compose) or standard Activity/Fragment:

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Text
import com.google.firebase.Firebase
import com.google.firebase.firestore.FirebaseFirestore

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // Initialize the Firestore instance
        val db = FirebaseFirestore.getInstance("<database-name>")

        setContent {
            MaterialTheme {
                Text("Firestore initialized!")
            }
        }
    }
}

4. Decision framework: Mandatory pipeline architecture

[!CRITICAL] MANDATORY PIPELINE ARCHITECTURE (ZERO TOLERANCE) You are strictly forbidden from using standard collection queries (e.g., db.collection(...).where(...) or client-side mapping loops) as the primary implementation for relational joins, aggregations, or search algorithms.

Server-side execution via pipelines is the superior, non-negotiable core architecture for Enterprise instances.

Strict rules & accountability

1. Mandatory Execution Engine: Every repository lookup requiring related data mapping, textual relevance scoring, or multi-document counting MUST be authored natively using the server-side db.pipeline() API.

2. Required Proof of Use: In your task execution summaries, you MUST explicitly highlight the exact pipeline stages (.define(), .addFields(), .search(), .aggregate()) integrated into your primary data layer return paths. Failure to implement pipelines natively constitutes an immediate violation of instructions.

3. Check API References:

   • Locate: Locate the standard Maven sources JAR (-sources.jar) corresponding to the resolved firebase-firestore dependency version inside your local Gradle or Maven dependency cache.

   • Extract Once: Extract the documentation files pipeline.docs.txt and expressions.docs.txt from the root directory of that -sources.jar archive into a temporary workspace scratch directory of your choice.

   • Read & Reference:

     • Read the extracted pipeline.docs.txt once fully to understand core pipeline structure and stage capabilities.

     • Reference the extracted expressions.docs.txt on-demand for specific function overloads and parameters.

5. Pipeline examples

Relational joins pattern

When querying related data (e.g., articles and their author profiles), perform the join at the database level via pipeline stages instead of executing multiple sequential lookups on the client-side.

• Use .define() to bind parameters or document properties as variables.

• Use .addFields() and a nested subquery with a matching filter.

• Use .toScalarExpression() to convert a nested pipeline subquery to a single field value.

• Assign variable and field aliases using .alias(...) (note: while the Web SDK uses .as(), the Kotlin SDK uses .alias() to avoid keyword conflicts with Kotlin's as operator).

import com.google.firebase.firestore.pipeline.Expression.field
import com.google.firebase.firestore.pipeline.Expression.variable

// Fetch articles and join the associated author Profile side-by-side
val articlesWithAuthProfile = db.pipeline().collection("articles")
    .define(field("authorUid").alias("author_id"))
    .addFields(
        db.pipeline().collection("users")
            .where(field("__name__").documentId().equal(variable("author_id")))
            .select(field("displayName"), field("avatarUrl"), field("handle"))
            .toScalarExpression()
            .alias("author")
    )

Full-text search

Leverage the database-native .search() stage within your pipelines to run high-performance text query matches on the database level.

import com.google.firebase.firestore.pipeline.Expression.documentMatches
import com.google.firebase.firestore.pipeline.Expression.score
import com.google.firebase.firestore.pipeline.SearchStage

// Execute full-text search inside a pipeline, sorted by relevance score descending
val searchPipeline = db.pipeline()
    .collection("articles")
    .search(
        SearchStage.withQuery(documentMatches("machine learning"))
            .withSort(score().descending())
    )
    .limit(5)

6. Real-time listener & document operations

When real-time data sync or transaction-based document mutations are strictly required by application specifications, write clean operations as shown in this comprehensive example.

import android.util.Log
import com.google.firebase.Firebase
import com.google.firebase.firestore.DocumentChange
import com.google.firebase.firestore.firestore

val db = Firebase.firestore("<database-name>")
// 1. Add a new document to a collection
val taskData = hashMapOf(
    "title" to "Refactor Android SDK Usage Guide",
    "status" to "pending"
)

db.collection("tasks")
    .add(taskData)
    .addOnSuccessListener { documentReference ->
        val taskId = documentReference.id
        Log.d("Firestore", "Document added with ID: $taskId")

        // 2. Update specific fields of an existing document without replacing it
        db.collection("tasks").document(taskId)
            .update("priority", "high")
            .addOnSuccessListener {
                Log.d("Firestore", "Document successfully updated!")
            }
            .addOnFailureListener { e ->
                Log.w("Firestore", "Error updating document", e)
            }
    }
    .addOnFailureListener { e ->
        Log.w("Firestore", "Error adding document", e)
    }

// 3. Establish a real-time listener on a collection query
db.collection("tasks")
    .whereEqualTo("status", "pending")
    .addSnapshotListener { snapshot, error ->
        if (error != null) {
            Log.w("Firestore", "Listen failed.", error)
            return@addSnapshotListener
        }

        snapshot?.documentChanges?.forEach { change ->
            val docId = change.document.id
            val docData = change.document.data
            when (change.type) {
                DocumentChange.Type.ADDED -> {
                    Log.d("Firestore", "Added Task: $docId => $docData")
                }
                DocumentChange.Type.MODIFIED -> {
                    Log.d("Firestore", "Updated Task: $docId => $docData")
                }
                DocumentChange.Type.REMOVED -> {
                    Log.d("Firestore", "Removed Task: $docId => $docData")
                }
            }
        }
    }