Documentation for the json1 and fts5 extensions

docs/content/en/_index.html

@@ -68,7 +68,7 @@ Here are some of the many ways moor helps you write awesome database code:
 	Moor will generate efficient SQL for Dart queries.</li>
 	<li><b>Easy to learn</b>: Instead of having to learn yet another ORM, moor lets you write queries in SQL and generates typesafe wrappers. Queries and tables
 	can also be written in Dart that looks similar to SQL without loosing type-safety.</li>
-	<li><b>Fast _and_ powerful</b>: With the new `moor_ffi` backend, moor can outperform key-value stores without putting any compromises and the integrity
+	<li><b>Fast _and_ powerful</b>: With the new `moor_ffi` backend, moor can outperform key-value stores without putting any compromises on the integrity
 	and flexibility that relational databases provide. Moor is the only major persistence library with builtin support for multiple isolates.</li>
 	<li><b>Well tested and production ready</b>: Each component of moor is verified by a wide range of unit and integration tests. Moor powers many Flutter apps
 	in production.</li>

docs/content/en/docs/Using SQL/extensions.md

@@ -0,0 +1,70 @@
+---
+title: "Supported sqlite extensions"
+weight: 10
+description: Information on json1 and fts5 support in the generator
+---
+
+_Note_: Since `moor_flutter` uses the sqlite version shipped on the device, the extensions might not
+be available on all devices. When using these extensions, using `moor_ffi` is strongly recommended.
+This enables the extensions on all Android devices and on iOS 11 and later.
+
+## json1
+
+To enable the json1 extension in moor files and compiled queries, modify the 
+[build options]({{<relref "../Advanced Features/builder_options.md">}}) to include 
+`json1` in the `sqlite_module` section.
+
+The sqlite extension doesn't require any special tables and works on all text columns. In moor
+files and compiled queries, all `json` functions are available after enabling the extension.
+
+Since the json extension is optional, enabling it in Dart requires a special import,
+`package:moor/extensions/json1.dart`. An example that uses json functions in Dart is shown below:
+```dart
+import 'package:moor/moor.dart';
+import 'package:moor/extensions/json1.dart';
+
+class Contacts extends Table {
+    IntColumn get id => integer().autoIncrement()();
+    TextColumn get data => text()();
+}
+
+@UseMoor(tables: [Contacts])
+class Database extends _$Database {
+  // constructor and schemaVersion omitted for brevity
+
+  Future<List<Contacts>> findContactsWithNumber(String number) {
+    return (select(contacts)
+      ..where((row) {
+        // assume the phone number is stored in a json key in the `data` column
+        final phoneNumber = row.data.jsonExtract<String, StringType>('phone_number');
+        return phoneNumber.equals(number);
+      })
+    ).get();
+  } 
+}
+```
+
+You can learn more about the json1 extension on [sqlite.org](https://www.sqlite.org/json1.html).
+
+## fts5
+
+The fts5 extensions provides full-text search capabilities in sqlite tables.
+To enable the fts5 extension in moor files and compiled queries, modify the 
+[build options]({{<relref "../Advanced Features/builder_options.md">}}) to include 
+`fts5` in the `sqlite_module` section.
+
+Just like you'd expect when using sqlite, you can create a fts5 table in a moor file
+by using a `CREATE VIRTUAL TABLE` statement.
+```sql
+CREATE VIRTUAL TABLE email USING fts5(sender, title, body);
+```
+
+Queries on fts5 tables work like expected:
+```sql
+emailsWithFts5: SELECT * FROM email WHERE email MATCH 'fts5' ORDER BY rank;
+```
+
+The `bm25`, `highlight` and `snippet` functions from fts5 can also be used in custom queries.
+
+It's not possible to declare fts5 tables, or queries on fts5 tables, in Dart.
+You can learn more about the fts5 extension on [sqlite.org](https://www.sqlite.org/fts5.html).

moor/lib/extensions/json1.dart

@@ -44,14 +44,17 @@ extension JsonExtensions on Expression<String, StringType> {
   /// Evaluating this expression will cause an error if [path] has an invalid
   /// format or `this` isn't well-formatted json.
   ///
-  /// Note that, since the return type of this function is dynamic, it can't be
-  /// used in [JoinedSelectStatement.addColumns]. It's also recommended to use
-  /// [Expression.equalsExp] with an explicit [Variable] instead of
-  /// [Expression.equals].
-  Expression jsonExtract(String path) {
+  /// Note that the [T] and [S] type parameters have to be set if this function
+  /// is used in [JoinedSelectStatement.addColumns] or compared via
+  /// [Expression.equals]. The [T] parameter denotes the mapped Dart type for
+  /// this expression, such as [String]. THe [S] parameter denotes the mapper
+  /// from moor that's responsible for mapping Dart objects to sqlite and vice
+  /// versa. If [T] was set to [String], the matching value for [S] would be
+  /// [StringType].
+  Expression<T, S> jsonExtract<T, S extends SqlType<T>>(String path) {
     return FunctionCallExpression('json_extract', [
       this,
       Variable.withString(path),
-    ]);
+    ]).dartCast<T, S>();
   }
 }