Implement custom queries

sally/lib/src/runtime/executor/executor.dart

@@ -57,7 +57,7 @@ abstract class GeneratedDatabase {
 
   /// Creates and auto-updating stream from the given select statement. This
   /// method should not be used directly.
-  Stream<List<T>> createStream<T>(SelectStatement<dynamic, T> stmt) =>
+  Stream<List<T>> createStream<T>(TableChangeListener<List<T>> stmt) =>
       streamQueries.registerStream(stmt);
 
   /// Handles database creation by delegating the work to the [migration]
@@ -112,12 +112,13 @@ abstract class GeneratedDatabase {
   /// You can use the [updates] parameter so that sally knows which tables are
   /// affected by your query. All select streams that depend on a table
   /// specified there will then issue another query.
-  Future<int> updateCustom(String query,
+  Future<int> customUpdate(String query,
       {List<Variable> variables = const [], Set<TableInfo> updates}) async {
     final ctx = GenerationContext(this);
     final mappedArgs = variables.map((v) => v.mapToSimpleValue(ctx)).toList();
 
-    final affectedRows = await executor.runUpdate(query, mappedArgs);
+    final affectedRows =
+        executor.doWhenOpened((_) => executor.runUpdate(query, mappedArgs));
 
     if (updates != null) {
       for (var table in updates) {
@@ -127,6 +128,25 @@ abstract class GeneratedDatabase {
 
     return affectedRows;
   }
+
+  /// Executes a custom select statement once. To use the variables, mark them
+  /// with a "?" in your [query]. They will then be changed to the appropriate
+  /// value.
+  Future<List<QueryRow>> customSelect(String query,
+      {List<Variable> variables = const []}) async {
+    return CustomSelectStatement(query, variables, Set(), this).read();
+  }
+
+  /// Creates a stream from a custom select statement.To use the variables, mark
+  /// them with a "?" in your [query]. They will then be changed to the
+  /// appropriate value. The stream will re-emit items when any table in
+  /// [readsFrom] changes, so be sure to set it to the set of tables your query
+  /// reads data from.
+  Stream<List<QueryRow>> customSelectStream(String query,
+      {List<Variable> variables = const [], Set<TableInfo> readsFrom}) {
+    final tables = readsFrom ?? Set();
+    return createStream(CustomSelectStatement(query, variables, tables, this));
+  }
 }
 
 /// A query executor is responsible for executing statements on a database and

sally/lib/src/runtime/executor/stream_queries.dart

@@ -2,6 +2,16 @@ import 'dart:async';
 
 import 'package:sally/sally.dart';
 
+/// Internal interface to mark classes that respond to table changes
+abstract class TableChangeListener<T> {
+  /// Called to check if this listener should update after the table with the
+  /// given name has changed.
+  bool isAffectedBy(String table);
+
+  /// Called to reload data from the table after it has changed.
+  Future<T> handleDataChanged();
+}
+
 /// Keeps track of active streams created from [SelectStatement]s and updates
 /// them when needed.
 class StreamQueryStore {
@@ -12,7 +22,7 @@ class StreamQueryStore {
   StreamQueryStore();
 
   /// Creates a new stream from the select statement.
-  Stream<List<T>> registerStream<T>(SelectStatement<dynamic, T> statement) {
+  Stream<List<T>> registerStream<T>(TableChangeListener<List<T>> statement) {
     final stream = _QueryStream(statement, this);
     _activeStreams.add(stream);
     return stream.stream;
@@ -34,13 +44,13 @@ class StreamQueryStore {
   }
 }
 
-class _QueryStream<T, D> {
-  final SelectStatement<T, D> query;
+class _QueryStream<T> {
+  final TableChangeListener<T> listener;
   final StreamQueryStore _store;
 
-  StreamController<List<D>> _controller;
+  StreamController<T> _controller;
 
-  Stream<List<D>> get stream {
+  Stream<T> get stream {
     _controller ??= StreamController.broadcast(
       onListen: _onListen,
       onCancel: _onCancel,
@@ -49,7 +59,7 @@ class _QueryStream<T, D> {
     return _controller.stream;
   }
 
-  _QueryStream(this.query, this._store);
+  _QueryStream(this.listener, this._store);
 
   void _onListen() {
     // first listener added, fetch query
@@ -70,14 +80,12 @@ class _QueryStream<T, D> {
     // Fetch data if it's needed, publish that data if it's possible.
     if (!_controller.hasListener) return;
 
-    final data = await query.get();
+    final data = await listener.handleDataChanged();
 
     if (!_controller.isClosed) {
       _controller.add(data);
     }
   }
 
-  bool isAffectedByTableChange(String table) {
-    return table == query.table.$tableName;
-  }
+  bool isAffectedByTableChange(String table) => listener.isAffectedBy(table);
 }

sally/lib/src/runtime/statements/select.dart

@@ -4,12 +4,14 @@ import 'package:sally/sally.dart';
 import 'package:sally/src/runtime/components/component.dart';
 import 'package:sally/src/runtime/components/limit.dart';
 import 'package:sally/src/runtime/executor/executor.dart';
+import 'package:sally/src/runtime/executor/stream_queries.dart';
 import 'package:sally/src/runtime/statements/query.dart';
 import 'package:sally/src/runtime/structure/table_info.dart';
 
 typedef OrderingTerm OrderClauseGenerator<T>(T tbl);
 
-class SelectStatement<T, D> extends Query<T, D> {
+class SelectStatement<T, D> extends Query<T, D>
+    implements TableChangeListener<List<D>> {
   SelectStatement(GeneratedDatabase database, TableInfo<T, D> table)
       : super(database, table);
 
@@ -47,4 +49,71 @@ class SelectStatement<T, D> extends Query<T, D> {
   Stream<List<D>> watch() {
     return database.createStream(this);
   }
+
+  @override
+  Future<List<D>> handleDataChanged() {
+    return get();
+  }
+
+  @override
+  bool isAffectedBy(String table) {
+    return table == super.table.$tableName;
+  }
+}
+
+class CustomSelectStatement implements TableChangeListener<List<QueryRow>> {
+  /// Tables this select statement reads from
+  final Set<TableInfo> tables;
+  final String query;
+  final List<Variable> variables;
+  final GeneratedDatabase db;
+
+  CustomSelectStatement(this.query, this.variables, this.tables, this.db);
+
+  Future<List<QueryRow>> read() => handleDataChanged();
+
+  @override
+  Future<List<QueryRow>> handleDataChanged() async {
+    final ctx = GenerationContext(db);
+    final mappedArgs = variables.map((v) => v.mapToSimpleValue(ctx)).toList();
+
+    final result =
+        await db.executor.doWhenOpened((e) => e.runSelect(query, mappedArgs));
+
+    return result.map((row) => QueryRow(row, db)).toList();
+  }
+
+  @override
+  bool isAffectedBy(String table) {
+    return tables.any((t) => t.$tableName == table);
+  }
+}
+
+/// For custom select statement, represents a row in the result set.
+class QueryRow {
+  final Map<String, dynamic> _data;
+  final GeneratedDatabase _db;
+
+  QueryRow(this._data, this._db);
+
+  /// Reads an arbitrary value from the row and maps it to a fitting dart type.
+  /// The dart type [T] must be supported by the type system of the database
+  /// used (mostly contains booleans, strings, integers and dates).
+  T read<T>(String key) {
+    final type = _db.typeSystem.forDartType<T>();
+
+    return type.mapFromDatabaseResponse(_data[key]);
+  }
+
+  /// Reads a bool from the column named [key].
+  bool readBool(String key) => read<bool>(key);
+
+  /// Reads a string from the column named [key].
+  String readString(String key) => read<String>(key);
+
+  /// Reads a int from the column named [key].
+  int readInt(String key) => read<int>(key);
+
+  /// Reads a [DateTime] from the column named [key].
+  DateTime readDateTime(String key) => read<DateTime>(key);
 }

sally/test/expressions/comparable_test.dart

@@ -2,8 +2,11 @@ import 'package:sally/sally.dart';
 import 'package:sally/src/runtime/components/component.dart';
 import 'package:test_api/test_api.dart';
 
+import '../data/tables/todos.dart';
+
 void main() {
   final expression = GeneratedIntColumn('col', false);
+  final db = TodoDb(null);
 
   final comparisons = {
     expression.isSmallerThan: '<',
@@ -24,7 +27,7 @@ void main() {
 
     comparisons.forEach((fn, value) {
       test('for operator $value', () {
-        final ctx = GenerationContext(null);
+        final ctx = GenerationContext(db);
 
         fn(compare).writeInto(ctx);
 
@@ -36,7 +39,7 @@ void main() {
   group('can compare with values', () {
     comparisonsVal.forEach((fn, value) {
       test('for operator $value', () {
-        final ctx = GenerationContext(null);
+        final ctx = GenerationContext(db);
 
         fn(12).writeInto(ctx);
 

sally/test/update_test.dart

@@ -65,13 +65,13 @@ void main() {
 
   group('custom updates', () {
     test('execute the correct sql', () async {
-      await db.updateCustom('DELETE FROM users');
+      await db.customUpdate('DELETE FROM users');
 
       verify(executor.runUpdate('DELETE FROM users', []));
     });
 
     test('map the variables correctly', () async {
-      await db.updateCustom(
+      await db.customUpdate(
           'DELETE FROM users WHERE name = ? AND birthdate < ?',
           variables: [
             Variable.withString('Name'),
@@ -87,11 +87,11 @@ void main() {
     test('returns information from executor', () async {
       when(executor.runUpdate(any, any)).thenAnswer((_) => Future.value(10));
 
-      expect(await db.updateCustom(''), 10);
+      expect(await db.customUpdate(''), 10);
     });
 
     test('informs about updated tables', () async {
-      await db.updateCustom('', updates: Set.of([db.users, db.todosTable]));
+      await db.customUpdate('', updates: Set.of([db.users, db.todosTable]));
 
       verify(streamQueries.handleTableUpdates('users'));
       verify(streamQueries.handleTableUpdates('todos'));

sally_flutter/README.md

@@ -189,6 +189,8 @@ If a column is nullable or has a default value (this includes auto-increments),
 can be omitted. All other fields must be set and non-null. The `insert` method will throw
 otherwise.
 
+'
+
 ## Migrations
 Sally provides a migration API that can be used to gradually apply schema changes after bumping
 the `schemaVersion` getter inside the `Database` class. To use it, override the `migration`
@@ -226,6 +228,8 @@ You can also add individual tables or drop them.
 
 ## TODO-List and current limitations
 ### Limitations (at the moment)
+Please note that a workaround for most on this list exists with custom statements.
+
 - No joins
 - No `group by` or window functions
 - Custom primary key support is very limited

sally_flutter/example/lib/database.dart

@@ -23,6 +23,13 @@ class Categories extends Table {
   TextColumn get description => text().named('desc')();
 }
 
+class CategoryWithCount {
+  final Category category;
+  final int count; // amount of entries in this category
+
+  CategoryWithCount(this.category, this.count);
+}
+
 @UseSally(tables: [Todos, Categories])
 class Database extends _$Database {
   Database()