adds snippets for ODM

packages/firebase_snippets_app/.gitignore

@@ -30,7 +30,6 @@
 .pub-cache/
 .pub/
 /build/
-*.g.dart
 
 # Web related
 lib/generated_plugin_registrant.dart

packages/firebase_snippets_app/lib/snippets/firestore_odm.dart

@@ -0,0 +1,27 @@
+// ignore_for_file: non_constant_identifier_names
+
+import 'package:firebase_snippets_app/snippets/firestore_odm/user_model.dart';
+import 'package:firebase_snippets_app/snippets/snippet_base.dart';
+
+class ODMSnippets extends DocSnippet {
+  @override
+  void runAll() {
+    // TODO: implement runAll
+  }
+
+  void references_performQueries() async {
+    // [START references_perform_queries]
+    usersRef.whereName(isEqualTo: 'John');
+    usersRef.whereAge(isGreaterThan: 18);
+    usersRef.orderByAge();
+    // ..etc!
+    // [END references_perform_queries]
+  }
+
+  void subCollection_accessSubCollection() async {
+    // [START sub_collection_access_sub_collection]
+    AddressCollectionReference addressesRef =
+        usersRef.doc('myDocumentID').addresses;
+    // [END sub_collection_access_sub_collection]
+  }
+}

packages/firebase_snippets_app/lib/snippets/firestore_odm/address_model.dart

@@ -0,0 +1,17 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'address_model.g.dart';
+
+// [START sub_collections_define]
+@JsonSerializable()
+class Address {
+  final String streetName;
+
+  Address({required this.streetName});
+
+  factory Address.fromJson(Map<String, Object?> json) =>
+      _$AddressFromJson(json);
+
+  Map<String, Object?> toJson() => _$AddressToJson(this);
+}
+// [END sub_collections_define]

packages/firebase_snippets_app/lib/snippets/firestore_odm/user_model.dart

@@ -0,0 +1,38 @@
+// ignore_for_file: non_constant_identifier_names
+
+import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';
+import 'package:firebase_snippets_app/snippets/firestore_odm/address_model.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'user_model.g.dart';
+
+@JsonSerializable()
+class User {
+  User({
+    required this.name,
+    required this.age,
+    required this.email,
+    required this.address,
+  }) {
+    _$assertUser(this);
+  }
+
+  factory User.fromJson(Map<String, Object?> json) => _$UserFromJson(json);
+
+  final String name;
+  final String email;
+  final Address address;
+
+  @Min(0)
+  final int age;
+
+  Map<String, Object?> toJson() => _$UserToJson(this);
+}
+// [END defining_models]
+
+// [START references_collection_ref]
+@Collection<User>('users')
+@Collection<Address>('users/*/addresses')
+final usersRef = UserCollectionReference();
+// [END references_collection_ref]

packages/firebase_snippets_app/lib/widgets/user.dart

@@ -0,0 +1,36 @@
+// ignore_for_file: use_key_in_widget_constructors
+
+import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';
+import 'package:flutter/material.dart';
+
+import '../snippets/firestore_odm/user_model.dart';
+
+// Not currently in the docs, so not currently being tested.
+class UserLabel extends StatelessWidget {
+  const UserLabel(this.id);
+
+  final String id;
+
+  @override
+  Widget build(BuildContext context) {
+    return FirestoreBuilder<UserDocumentSnapshot>(
+        // Access a specific document
+        ref: usersRef.doc(id),
+        builder: (context, AsyncSnapshot<UserDocumentSnapshot> snapshot,
+            Widget? child) {
+          if (snapshot.hasError) return const Text('Something went wrong!');
+          if (!snapshot.hasData) return const Text('Loading user...');
+
+          // Access the UserDocumentSnapshot
+          UserDocumentSnapshot documentSnapshot = snapshot.requireData;
+
+          if (!documentSnapshot.exists) {
+            return const Text('User does not exist.');
+          }
+
+          User user = documentSnapshot.data!;
+
+          return Text('User name: ${user.name}, age ${user.age}');
+        });
+  }
+}

packages/firebase_snippets_app/lib/widgets/users_list.dart

@@ -0,0 +1,33 @@
+import 'package:cloud_firestore_odm/cloud_firestore_odm.dart';
+import 'package:flutter/material.dart';
+
+import '../snippets/firestore_odm/user_model.dart';
+
+// Not currently in the docs, so not currently being tested.
+class UsersList extends StatelessWidget {
+  const UsersList({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return FirestoreBuilder<UserQuerySnapshot>(
+        ref: usersRef,
+        builder: (context, AsyncSnapshot<UserQuerySnapshot> snapshot,
+            Widget? child) {
+          if (snapshot.hasError) return const Text('Something went wrong!');
+          if (!snapshot.hasData) return const Text('Loading users...');
+
+          // Access the QuerySnapshot
+          UserQuerySnapshot querySnapshot = snapshot.requireData;
+
+          return ListView.builder(
+            itemCount: querySnapshot.docs.length,
+            itemBuilder: (context, index) {
+              // Access the User instance
+              User user = querySnapshot.docs[index].data;
+
+              return Text('User name: ${user.name}, age ${user.age}');
+            },
+          );
+        });
+  }
+}