Support + and - operators on DateTime

docs/content/en/docs/Advanced Features/expressions.md

@@ -76,6 +76,13 @@ that you can use operators and comparisons on them.
 To obtain the current date or the current time as an expression, use the `currentDate` 
 and `currentDateAndTime` constants provided by moor.
 
+You can also use the `+` and `-` operators to add or subtract a duration from a time column:
+
+```dart
+final toNextWeek = TasksCompanion.custom(dueDate: tasks.dueDate + Duration(weeks: 1));
+update(tasks).write(toNextWeek);
+```
+
 ## `IN` and `NOT IN`
 You can check whether an expression is in a list of values by using the `isIn` and `isNotIn`
 methods:

moor/lib/src/runtime/query_builder/expressions/datetimes.dart

@@ -44,6 +44,18 @@ extension DateTimeExpressions on Expression<DateTime> {
   // for moor, date times are just unix timestamps, so we don't need to rewrite
   // anything when converting
   Expression<int> get secondsSinceEpoch => dartCast();
+
+  /// Adds [duration] from this date.
+  Expression<DateTime> operator +(Duration duration) {
+    return _BaseInfixOperator(this, '+', Variable<int>(duration.inSeconds),
+        precedence: Precedence.plusMinus);
+  }
+
+  /// Subtracts [duration] from this date.
+  Expression<DateTime> operator -(Duration duration) {
+    return _BaseInfixOperator(this, '-', Variable<int>(duration.inSeconds),
+        precedence: Precedence.plusMinus);
+  }
 }
 
 /// Expression that extracts components out of a date time by using the builtin

moor/lib/src/runtime/query_builder/expressions/expression.dart

@@ -203,13 +203,13 @@ abstract class _InfixOperator<D> extends Expression<D> {
 
 class _BaseInfixOperator<D> extends _InfixOperator<D> {
   @override
-  final Expression<D> left;
+  final Expression left;
 
   @override
   final String operator;
 
   @override
-  final Expression<D> right;
+  final Expression right;
 
   @override
   final Precedence precedence;

moor/lib/src/runtime/types/sql_types.dart

@@ -84,7 +84,10 @@ class IntType extends SqlType<int> {
   const IntType();
 
   @override
-  int mapFromDatabaseResponse(dynamic response) => response as int;
+  int mapFromDatabaseResponse(dynamic response) {
+    if (response is int) return response;
+    return int.parse(response.toString());
+  }
 
   @override
   String mapToSqlConstant(int content) => content?.toString() ?? 'NULL';

moor/test/data/utils/expect_generated.dart

@@ -4,7 +4,7 @@ import 'package:test/test.dart';
 /// Matcher for [Component]-subclasses. Expect that a component generates the
 /// matching [sql] and, optionally, the matching [variables].
 Matcher generates(dynamic sql, [dynamic variables]) {
-  final variablesMatcher = variables != null ? wrapMatcher(variables) : null;
+  final variablesMatcher = variables != null ? wrapMatcher(variables) : isEmpty;
   return _GeneratesSqlMatcher(wrapMatcher(sql), variablesMatcher);
 }
 
@@ -19,8 +19,9 @@ class _GeneratesSqlMatcher extends Matcher {
     description = description.add('generates sql ').addDescriptionOf(_matchSql);
 
     if (_matchVariables != null) {
-      description =
-          description.add('and variables').addDescriptionOf(_matchVariables);
+      description = description
+          .add(' and variables that ')
+          .addDescriptionOf(_matchVariables);
     }
     return description;
   }
@@ -36,15 +37,15 @@ class _GeneratesSqlMatcher extends Matcher {
 
       mismatchDescription = mismatchDescription.add('generated $sql, which ');
       mismatchDescription = _matchSql.describeMismatch(
-          sql, mismatchDescription, matchState, verbose);
+          sql, mismatchDescription, matchState['sql_match'] as Map, verbose);
     }
     if (matchState.containsKey('vars')) {
       final vars = matchState['vars'] as List;
 
       mismatchDescription =
-          mismatchDescription.add('used variables $vars, which ');
+          mismatchDescription.add('generated variables $vars, which ');
       mismatchDescription = _matchVariables.describeMismatch(
-          vars, mismatchDescription, matchState, verbose);
+          vars, mismatchDescription, matchState['vars_match'] as Map, verbose);
     }
     return mismatchDescription;
   }
@@ -52,7 +53,7 @@ class _GeneratesSqlMatcher extends Matcher {
   @override
   bool matches(dynamic item, Map matchState) {
     if (item is! Component) {
-      addStateInfo(matchState, {'wrong_type': true});
+      matchState['wrong_type'] = true;
       return false;
     }
 
@@ -62,14 +63,18 @@ class _GeneratesSqlMatcher extends Matcher {
 
     var matches = true;
 
-    if (!_matchSql.matches(ctx.sql, matchState)) {
-      addStateInfo(matchState, {'sql': ctx.sql});
+    final sqlMatchState = {};
+    if (!_matchSql.matches(ctx.sql, sqlMatchState)) {
+      matchState['sql'] = ctx.sql;
+      matchState['sql_match'] = sqlMatchState;
       matches = false;
     }
 
+    final argsMatchState = {};
     if (_matchVariables != null &&
-        !_matchVariables.matches(ctx.boundVariables, matchState)) {
-      addStateInfo(matchState, {'vars': ctx.boundVariables});
+        !_matchVariables.matches(ctx.boundVariables, argsMatchState)) {
+      matchState['vars'] = ctx.boundVariables;
+      matchState['vars_match'] = argsMatchState;
       matches = false;
     }
 

moor/test/expressions/datetime_expression_test.dart

@@ -2,6 +2,7 @@ import 'package:moor/moor.dart';
 import 'package:test/test.dart';
 
 import '../data/utils/expect_equality.dart';
+import '../data/utils/expect_generated.dart';
 
 typedef _Extractor = Expression<int> Function(Expression<DateTime> d);
 
@@ -37,4 +38,13 @@ void main() {
 
     expect(ctx.sql, 'strftime(\'%s\', CURRENT_TIMESTAMP) + 10');
   });
+
+  test('plus and minus durations', () {
+    final expr = currentDateAndTime +
+        const Duration(days: 3) -
+        const Duration(seconds: 5);
+
+    expect(expr,
+        generates('strftime(\'%s\', CURRENT_TIMESTAMP) + ? - ?', [259200, 5]));
+  });
 }

moor/test/expressions/expressions_integration_test.dart

@@ -0,0 +1,35 @@
+import 'package:moor/moor.dart';
+@TestOn('vm')
+import 'package:test/test.dart';
+import 'package:moor_ffi/moor_ffi.dart';
+
+import '../data/tables/todos.dart';
+
+void main() {
+  TodoDb db;
+
+  setUp(() async {
+    db = TodoDb(VmDatabase.memory());
+
+    // we selectOnly from users for the lack of a better option. Insert one
+    // row so that getSingle works
+    await db.into(db.users).insert(
+        UsersCompanion.insert(name: 'User name', profilePicture: Uint8List(0)));
+  });
+
+  tearDown(() => db.close());
+
+  test('plus and minus on DateTimes', () async {
+    final nowExpr = currentDateAndTime;
+    final tomorrow = nowExpr + const Duration(days: 1);
+    final nowStamp = nowExpr.secondsSinceEpoch;
+    final tomorrowStamp = tomorrow.secondsSinceEpoch;
+
+    final row = await (db.selectOnly(db.users)
+          ..addColumns([nowStamp, tomorrowStamp]))
+        .getSingle();
+
+    expect(row.read(tomorrowStamp) - row.read(nowStamp),
+        const Duration(days: 1).inSeconds);
+  });
+}

moor/test/update_test.dart

@@ -118,6 +118,20 @@ void main() {
     });
   });
 
+  test('can update with custom companions', () async {
+    await db.update(db.todosTable).replace(TodosTableCompanion.custom(
+          id: const Variable(4),
+          content: db.todosTable.content,
+          targetDate: db.todosTable.targetDate + const Duration(days: 1),
+        ));
+
+    verify(executor.runUpdate(
+      'UPDATE todos SET content = content, target_date = target_date + ? '
+      'WHERE id = ?;',
+      argThat(equals([86400, 4])),
+    ));
+  });
+
   group('custom updates', () {
     test('execute the correct sql', () async {
       await db.customUpdate('DELETE FROM users');