Add writeToColumnsMixin

drift_dev/lib/src/analysis/options.dart

@@ -94,6 +94,9 @@ class DriftOptions {
   @JsonKey(name: 'case_from_dart_to_sql', defaultValue: CaseFromDartToSql.snake)
   final CaseFromDartToSql caseFromDartToSql;
 
+  @JsonKey(name: 'write_to_columns_mixins', defaultValue: false)
+  final bool writeToColumnsMixins;
+
   @internal
   const DriftOptions.defaults({
     this.generateFromJsonStringConstructor = false,
@@ -115,6 +118,7 @@ class DriftOptions {
     this.storeDateTimeValuesAsText = false,
     this.dialect = const DialectOptions(SqlDialect.sqlite, null),
     this.caseFromDartToSql = CaseFromDartToSql.snake,
+    this.writeToColumnsMixins = false,
   });
 
   DriftOptions({
@@ -136,6 +140,7 @@ class DriftOptions {
     required this.sqliteAnalysisOptions,
     required this.storeDateTimeValuesAsText,
     required this.caseFromDartToSql,
+    required this.writeToColumnsMixins,
     this.dialect,
   }) {
     // ignore: deprecated_member_use_from_same_package

drift_dev/lib/src/generated/analysis/options.g.dart

@@ -31,7 +31,8 @@ DriftOptions _$DriftOptionsFromJson(Map json) => $checkedCreate(
             'named_parameters_always_required',
             'scoped_dart_components',
             'store_date_time_values_as_text',
-            'case_from_dart_to_sql'
+            'case_from_dart_to_sql',
+            'write_to_columns_mixins'
           ],
         );
         final val = DriftOptions(
@@ -83,6 +84,8 @@ DriftOptions _$DriftOptionsFromJson(Map json) => $checkedCreate(
               (v) =>
                   $enumDecodeNullable(_$CaseFromDartToSqlEnumMap, v) ??
                   CaseFromDartToSql.snake),
+          writeToColumnsMixins: $checkedConvert(
+              'write_to_columns_mixins', (v) => v as bool? ?? false),
           dialect: $checkedConvert('sql',
               (v) => v == null ? null : DialectOptions.fromJson(v as Map)),
         );
@@ -110,6 +113,7 @@ DriftOptions _$DriftOptionsFromJson(Map json) => $checkedCreate(
         'sqliteAnalysisOptions': 'sqlite',
         'storeDateTimeValuesAsText': 'store_date_time_values_as_text',
         'caseFromDartToSql': 'case_from_dart_to_sql',
+        'writeToColumnsMixins': 'write_to_columns_mixins',
         'dialect': 'sql'
       },
     );
@@ -142,6 +146,7 @@ Map<String, dynamic> _$DriftOptionsToJson(DriftOptions instance) =>
       'store_date_time_values_as_text': instance.storeDateTimeValuesAsText,
       'case_from_dart_to_sql':
           _$CaseFromDartToSqlEnumMap[instance.caseFromDartToSql]!,
+      'write_to_columns_mixins': instance.writeToColumnsMixins,
     };
 
 const _$SqlModuleEnumMap = {

drift_dev/lib/src/writer/tables/update_companion_writer.dart

@@ -46,6 +46,9 @@ class UpdateCompanionWriter {
     if (table.existingRowClass?.generateInsertable ?? false) {
       _writeToCompanionExtension();
     }
+    if (scope.options.writeToColumnsMixins) {
+      _writeToColumnsMixin();
+    }
   }
 
   void _writeFields() {
@@ -263,4 +266,82 @@ class UpdateCompanionWriter {
       ..write('return $insertableClass(this);\n')
       ..write('}\n}\n');
   }
+
+  void _writeToColumnsMixin() {
+    final info = table.existingRowClass;
+    if (info == null) return;
+
+    _buffer.write('mixin ${table.nameOfRowClass}Columns ');
+
+    final type = _emitter.dartCode(_emitter.writer.rowType(table));
+    _buffer.writeln('implements ${_emitter.drift('Insertable')}<$type> {');
+
+    for (final column in columns) {
+      if (column.documentationComment != null) {
+        _buffer.write('${column.documentationComment}\n');
+      }
+      final typeName = _emitter.dartCode(_emitter.dartType(column));
+      _buffer.writeln('$typeName get ${column.nameInDart};');
+    }
+
+    _writeTableToColumnsOverride();
+    _buffer.write('}');
+  }
+
+  void _writeTableToColumnsOverride() {
+    final expression = _emitter.drift('Expression');
+    final variable = _emitter.drift('Variable');
+
+    _buffer
+      ..write('@override\nMap<String, $expression> toColumns'
+          '(bool nullToAbsent) {\n')
+      ..write('final map = <String, $expression> {};');
+
+    for (final column in columns) {
+      // Generated column - cannot be used for inserts or updates
+      if (column.isGenerated) continue;
+
+      // We include all columns that are not null. If nullToAbsent is false, we
+      // also include null columns. When generating NNBD code, we can include
+      // non-nullable columns without an additional null check since we know
+      // the values aren't going to be null.
+      final needsNullCheck = column.nullableInDart;
+      final needsScope = needsNullCheck || column.typeConverter != null;
+      if (needsNullCheck) {
+        _buffer.write('if (!nullToAbsent || ${column.nameInDart} != null)');
+      }
+      if (needsScope) _buffer.write('{');
+
+      final typeName =
+          _emitter.dartCode(_emitter.variableTypeCode(column, nullable: false));
+      final mapSetter = 'map[${asDartLiteral(column.nameInSql)}] = '
+          '$variable<$typeName>';
+
+      if (column.typeConverter != null) {
+        // apply type converter before writing the variable
+        final converter = column.typeConverter!;
+
+        _emitter
+          ..write('final converter = ')
+          ..writeDart(_emitter.writer
+              .readConverter(converter, forNullable: column.nullable))
+          ..writeln(';')
+          ..write(mapSetter)
+          ..write('(converter.toSql(${column.nameInDart})');
+        _buffer.write(');');
+      } else {
+        // no type converter. Write variable directly
+        _buffer
+          ..write(mapSetter)
+          ..write('(')
+          ..write(column.nameInDart)
+          ..write(');');
+      }
+
+      // This one closes the optional if from before.
+      if (needsScope) _buffer.write('}');
+    }
+
+    _buffer.write('return map; \n}\n');
+  }
 }