Add length extension for blob expressions

Closes #3778

Author: simolus3

drift/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.33.0-dev
+
+- Add `length` extension for blob expressions.
+
 ## 2.32.1
 
 - DevTools extension: Make error messages selectable.

drift/lib/src/runtime/query_builder/expressions/binary.dart

@@ -0,0 +1,11 @@
+import 'dart:typed_data';
+
+import '../query_builder.dart';
+
+/// Defines methods that operate on a column storing [Uint8List] values.
+extension BlobExpressionOperators on Expression<Uint8List> {
+  /// The length of this blob, in bytes.
+  Expression<int> get length {
+    return FunctionCallExpression('LENGTH', [this]);
+  }
+}

drift/lib/src/runtime/query_builder/query_builder.dart

@@ -30,6 +30,7 @@ import 'expressions/internal.dart';
 import 'helpers.dart';
 
 export 'components/table_valued_function.dart';
+export 'expressions/binary.dart';
 export 'expressions/bitwise.dart';
 export 'expressions/case_when.dart';
 export 'on_table.dart';

drift/test/database/expressions/expressions_integration_test.dart

@@ -188,6 +188,11 @@ void main() {
       });
     });
 
+    test('blob length', () async {
+      expect(await eval(Constant(Uint8List(0)).length), 0);
+      expect(await eval(Variable(Uint8List(12)).length), 12);
+    });
+
     test('coalesce', () async {
       final expr = coalesce<int>([const Constant(null), const Constant(3)]);
 

future/drift3/lib/src/query_builder.dart

@@ -9,6 +9,7 @@ export 'query_builder/clauses/where.dart';
 export 'query_builder/expressions/aggregate.dart';
 export 'query_builder/expressions/algebra.dart';
 export 'query_builder/expressions/bitwise.dart';
+export 'query_builder/expressions/blob.dart';
 export 'query_builder/expressions/boolean.dart';
 export 'query_builder/expressions/case_when.dart';
 export 'query_builder/expressions/comparable.dart';

future/drift3/lib/src/query_builder/expressions/blob.dart

@@ -0,0 +1,10 @@
+import 'dart:typed_data';
+
+import 'expression.dart';
+import 'functions.dart';
+
+/// Defines operations on blob ([Uint8List]) values.
+extension BlobExpressionOperators on Expression<Uint8List> {
+  /// The length of this blob, in bytes.
+  Expression<int> get length => FunctionCallExpression('LENGTH', [this]);
+}

future/drift3/test/query_builder/expressions/expressions_integration_test.dart

@@ -236,6 +236,11 @@ void main() {
       });
     });
 
+    test('blob length', () async {
+      expect(await eval(Literal(Uint8List(0)).length), 0);
+      expect(await eval(Variable(Uint8List(12)).length), 12);
+    });
+
     test('coalesce', () async {
       final expr = coalesce<int>([const Literal(null), const Literal(3)]);