Move code to `table_writer.dart`

Use mixin in data class when enabled

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

@@ -48,11 +48,15 @@ class DataClassWriter {
     _buffer.write('class ${table.nameOfRowClass} extends $parentClass ');
 
     if (isInsertable) {
+      if (scope.options.writeToColumnsMixins) {
+        _buffer.writeln('with ${table.entityInfoName}ToColumns {');
+      } else {
         // The data class is only an insertable if we can actually insert rows
         // into the target entity.
         final type = _emitter.dartCode(_emitter.writer.rowType(table));
 
         _buffer.writeln('implements ${_emitter.drift('Insertable')}<$type> {');
+      }
     } else {
       _buffer.writeln('{');
     }
@@ -88,7 +92,9 @@ class DataClassWriter {
       ..write('});');
 
     if (isInsertable) {
+      if (!scope.options.writeToColumnsMixins) {
         _writeToColumnsOverride();
+      }
       if (scope.options.dataClassToCompanions) {
         _writeToCompanion();
       }

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

@@ -265,11 +265,17 @@ class TableWriter extends TableOrViewWriter {
       scope.generationOptions.isGeneratingForSchema;
 
   void writeInto() {
+    emitter = scope.leaf();
+
     writeDataClass();
     writeTableInfoClass();
   }
 
   void writeDataClass() {
+    if (scope.options.writeToColumnsMixins) {
+      writeToColumnsMixin();
+    }
+
     if (scope.generationOptions.writeDataClasses) {
       final existing = table.existingRowClass;
       if (existing != null) {
@@ -277,7 +283,7 @@ class TableWriter extends TableOrViewWriter {
         // user. However, if the existing row type is a record, it is helpful
         // to generate a typedef for it.
         if (existing.isRecord) {
-          scope.leaf()
+          emitter
             ..write('typedef ${table.nameOfRowClass} = ')
             ..writeDart(AnnotatedDartCode.type(existing.targetType))
             ..write(';');
@@ -293,8 +299,6 @@ class TableWriter extends TableOrViewWriter {
   }
 
   void writeTableInfoClass() {
-    emitter = scope.leaf();
-
     if (!scope.generationOptions.writeDataClasses) {
       // Write a small table header without data class
       buffer
@@ -362,6 +366,81 @@ class TableWriter extends TableOrViewWriter {
     buffer.write('}');
   }
 
+  void writeToColumnsMixin() {
+    buffer.write('mixin ${table.baseDartName}ToColumns ');
+
+    final type = emitter.dartCode(emitter.writer.rowType(table));
+    buffer.writeln('implements ${emitter.drift('Insertable')}<$type> {');
+
+    for (final column in table.columns) {
+      if (column.documentationComment != null) {
+        buffer.write('${column.documentationComment}\n');
+      }
+      final typeName = emitter.dartCode(emitter.dartType(column));
+      buffer.writeln('$typeName get ${column.nameInDart};');
+    }
+
+    _writeToColumnsOverride();
+    buffer.write('}');
+  }
+
+  void _writeToColumnsOverride() {
+    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 table.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');
+  }
+
   void _writeConvertersAsStaticFields() {
     for (final converter in table.appliedConverters) {
       final typeName =

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

@@ -46,9 +46,6 @@ class UpdateCompanionWriter {
     if (table.existingRowClass?.generateInsertable ?? false) {
       _writeToCompanionExtension();
     }
-    if (scope.options.writeToColumnsMixins) {
-      _writeToColumnsMixin();
-    }
   }
 
   void _writeFields() {
@@ -266,82 +263,4 @@ class UpdateCompanionWriter {
       ..write('return $insertableClass(this);\n')
       ..write('}\n}\n');
   }
-
-  void _writeToColumnsMixin() {
-    final info = table.existingRowClass;
-    if (info == null) return;
-
-    _buffer.write('mixin ${table.baseDartName}ToColumns ');
-
-    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');
-  }
 }