Add example for reflective update

docs/lib/snippets/modular/schema_inspection.dart

@@ -33,4 +33,38 @@ extension FindTodoEntryById on GeneratedDatabase {
     return select(todos)..where((row) => row.id.equals(id));
   }
   // #enddocregion findTodoEntryById
+
+  // #docregion updateTitle
+  Future<Row?> updateTitle<T extends TableInfo<Table, Row>, Row>(
+      T table, int id, String newTitle) async {
+    final columnsByName = table.columnsByName;
+    final stmt = update(table)
+      ..where((tbl) {
+        final idColumn = columnsByName['id'];
+
+        if (idColumn == null) {
+          throw ArgumentError.value(
+              this, 'this', 'Must be a table with an id column');
+        }
+
+        if (idColumn.type != DriftSqlType.int) {
+          throw ArgumentError('Column `id` is not an integer');
+        }
+
+        return idColumn.equals(id);
+      });
+
+    final rows = await stmt.writeReturning(RawValuesInsertable({
+      'title': Variable<String>(newTitle),
+    }));
+
+    return rows.singleOrNull;
+  }
+  // #enddocregion updateTitle
+
+  // #docregion updateTodo
+  Future<Todo?> updateTodoTitle(int id, String newTitle) {
+    return updateTitle(todos, id, newTitle);
+  }
+  // #enddocregion updateTodo
 }

docs/pages/docs/Dart API/schema_inspection.md

@@ -49,8 +49,24 @@ To call this extension, `await myDatabase.todos.findById(3).getSingle()` could b
 A nice thing about defining the method as an extension is that type inference works really well - calling `findById` on `todos`
 returns a `Todo` instance, the generated data class for this table.
 
+## Updates and inserts
+
 The same approach also works to construct update, delete and insert statements (although those require a [TableInfo] instead of a [ResultSetImplementation]
 as views are read-only).
+Also, updates and inserts use an `Insertable` object which represents a partial row of updated or
+inserted columns, respectively.
+With a known table, one would use the generated typed `Companion` objects for that.
+But this can also be done with schema introspection thanks to the `RawValuesInsertable`, which
+can be used as a generic `Insertable` backed by a map of column names to values.
+
+This example builds on the previous one to update the `title` column of a generic table based on a filter
+of the `id` column:
+
+{% include "blocks/snippet" snippets = snippets name = 'updateTitle' %}
+
+This method can then be called like this:
+
+{% include "blocks/snippet" snippets = snippets name = 'updateTodo' %}
 
 Hopefully, this page gives you some pointers to start reflectively inspecting your drift databases.
 The linked Dart documentation also expains the concepts in more detail.