Handle nullable converters for compiled queries

drift/lib/src/runtime/types/custom_type.dart

@@ -114,6 +114,24 @@ abstract class NullAwareTypeConverter<D, S extends Object>
   /// Map a non-null value from an object in Dart into something that will be
   /// understood by the database.
   S requireToSql(D value);
+
+  /// Invokes a non-nullable [inner] type converter for a single conversion from
+  /// SQL to Dart.
+  ///
+  /// Returns `null` if [sqlValue] is `null`, [TypeConverter.fromSql] otherwise.
+  /// This method is mostly intended to be used for code generated by drift-dev.
+  static D? wrapFromSql<D, S>(TypeConverter<D, S> inner, S? sqlValue) {
+    return sqlValue == null ? null : inner.fromSql(sqlValue);
+  }
+
+  /// Invokes a non-nullable [inner] type converter for a single conversion from
+  /// Dart to SQL.
+  ///
+  /// Returns `null` if [dartValue] is `null`, [TypeConverter.toSql] otherwise.
+  /// This method is mostly intended to be used for code generated by drift-dev.
+  static S? wrapToSql<D, S>(TypeConverter<D, S> inner, D? dartValue) {
+    return dartValue == null ? null : inner.toSql(dartValue);
+  }
 }
 
 class _NullWrappingTypeConverter<D, S extends Object>

drift/test/generated/custom_tables.g.dart

@@ -24,7 +24,7 @@ class Config extends DataClass implements Insertable<Config> {
           .mapFromDatabaseResponse(data['${effectivePrefix}config_key'])!,
       configValue: const StringType()
           .mapFromDatabaseResponse(data['${effectivePrefix}config_value']),
-      syncState: ConfigTable.$converter0.fromSql(const IntType()
+      syncState: ConfigTable.$converter0n.fromSql(const IntType()
           .mapFromDatabaseResponse(data['${effectivePrefix}sync_state'])),
       syncStateImplicit: ConfigTable.$converter1.fromSql(const IntType()
           .mapFromDatabaseResponse(
@@ -39,7 +39,7 @@ class Config extends DataClass implements Insertable<Config> {
       map['config_value'] = Variable<String?>(configValue);
     }
     if (!nullToAbsent || syncState != null) {
-      final converter = ConfigTable.$converter0;
+      final converter = ConfigTable.$converter0n;
       map['sync_state'] = Variable<int?>(converter.toSql(syncState));
     }
     if (!nullToAbsent || syncStateImplicit != null) {
@@ -182,7 +182,7 @@ class ConfigCompanion extends UpdateCompanion<Config> {
       map['config_value'] = Variable<String?>(configValue.value);
     }
     if (syncState.present) {
-      final converter = ConfigTable.$converter0;
+      final converter = ConfigTable.$converter0n;
       map['sync_state'] = Variable<int?>(converter.toSql(syncState.value));
     }
     if (syncStateImplicit.present) {
@@ -229,7 +229,7 @@ class ConfigTable extends Table with TableInfo<ConfigTable, Config> {
               type: const IntType(),
               requiredDuringInsert: false,
               $customConstraints: '')
-          .withConverter<SyncType?>(ConfigTable.$converter0);
+          .withConverter<SyncType?>(ConfigTable.$converter0n);
   final VerificationMeta _syncStateImplicitMeta =
       const VerificationMeta('syncStateImplicit');
   late final GeneratedColumnWithTypeConverter<SyncType?, int?>
@@ -281,11 +281,12 @@ class ConfigTable extends Table with TableInfo<ConfigTable, Config> {
     return ConfigTable(attachedDatabase, alias);
   }
 
-  static TypeConverter<SyncType?, int?> $converter0 =
+  static TypeConverter<SyncType, int> $converter0 = const SyncTypeConverter();
-      NullAwareTypeConverter.wrap(const SyncTypeConverter());
   static TypeConverter<SyncType?, int?> $converter1 =
       const NullAwareTypeConverter.wrap(
           EnumIndexConverter<SyncType>(SyncType.values));
+  static TypeConverter<SyncType?, int?> $converter0n =
+      NullAwareTypeConverter.wrap($converter0);
   @override
   bool get isStrict => true;
   @override
@@ -1476,7 +1477,7 @@ class MyViewData extends DataClass {
           .mapFromDatabaseResponse(data['${effectivePrefix}config_key'])!,
       configValue: const StringType()
           .mapFromDatabaseResponse(data['${effectivePrefix}config_value']),
-      syncState: ConfigTable.$converter0.fromSql(const IntType()
+      syncState: ConfigTable.$converter0n.fromSql(const IntType()
           .mapFromDatabaseResponse(data['${effectivePrefix}sync_state'])),
       syncStateImplicit: ConfigTable.$converter1.fromSql(const IntType()
           .mapFromDatabaseResponse(
@@ -1579,7 +1580,7 @@ class MyView extends ViewInfo<MyView, MyViewData> implements HasResultSet {
   late final GeneratedColumnWithTypeConverter<SyncType?, int?> syncState =
       GeneratedColumn<int?>('sync_state', aliasedName, true,
               type: const IntType())
-          .withConverter<SyncType?>(ConfigTable.$converter0);
+          .withConverter<SyncType?>(ConfigTable.$converter0n);
   late final GeneratedColumnWithTypeConverter<SyncType?, int?>
       syncStateImplicit = GeneratedColumn<int?>(
               'sync_state_implicit', aliasedName, true,
@@ -1677,7 +1678,8 @@ abstract class _$CustomTablesDb extends GeneratedDatabase {
     return customSelect(
         'SELECT config_key FROM config WHERE ${generatedpred.sql} AND(sync_state = ?1 OR sync_state_implicit IN ($expandedvar2))',
         variables: [
-          Variable<int?>(ConfigTable.$converter0.toSql(var1)),
+          Variable<int?>(
+              NullAwareTypeConverter.wrapToSql(ConfigTable.$converter0, var1)),
           ...generatedpred.introducedVariables,
           for (var $ in var2) Variable<int?>(ConfigTable.$converter1.toSql($))
         ],
@@ -1775,8 +1777,8 @@ abstract class _$CustomTablesDb extends GeneratedDatabase {
         rowid: row.read<int>('rowid'),
         configKey: row.read<String>('config_key'),
         configValue: row.read<String?>('config_value'),
-        syncState:
+        syncState: NullAwareTypeConverter.wrapFromSql(
-            ConfigTable.$converter0.fromSql(row.read<int?>('sync_state')),
+            ConfigTable.$converter0, row.read<int?>('sync_state')),
         syncStateImplicit: ConfigTable.$converter1
             .fromSql(row.read<int?>('sync_state_implicit')),
       );

drift/test/generated/todos.g.dart

@@ -37,7 +37,7 @@ class Category extends DataClass implements Insertable<Category> {
     map['desc'] = Variable<String>(description);
     {
       final converter = $CategoriesTable.$converter0;
-      map['priority'] = Variable<int>(converter.toSql(priority)!);
+      map['priority'] = Variable<int>(converter.toSql(priority));
     }
     return map;
   }
@@ -162,7 +162,7 @@ class CategoriesCompanion extends UpdateCompanion<Category> {
     }
     if (priority.present) {
       final converter = $CategoriesTable.$converter0;
-      map['priority'] = Variable<int>(converter.toSql(priority.value)!);
+      map['priority'] = Variable<int>(converter.toSql(priority.value));
     }
     return map;
   }
@@ -1109,7 +1109,7 @@ class TableWithoutPKCompanion extends UpdateCompanion<CustomRowClass> {
     }
     if (custom.present) {
       final converter = $TableWithoutPKTable.$converter0;
-      map['custom'] = Variable<String>(converter.toSql(custom.value)!);
+      map['custom'] = Variable<String>(converter.toSql(custom.value));
     }
     return map;
   }
@@ -1246,7 +1246,7 @@ class PureDefault extends DataClass implements Insertable<PureDefault> {
   factory PureDefault.fromData(Map<String, dynamic> data, {String? prefix}) {
     final effectivePrefix = prefix ?? '';
     return PureDefault(
-      txt: $PureDefaultsTable.$converter0.fromSql(const StringType()
+      txt: $PureDefaultsTable.$converter0n.fromSql(const StringType()
           .mapFromDatabaseResponse(data['${effectivePrefix}insert'])),
     );
   }
@@ -1254,7 +1254,7 @@ class PureDefault extends DataClass implements Insertable<PureDefault> {
   Map<String, Expression> toColumns(bool nullToAbsent) {
     final map = <String, Expression>{};
     if (!nullToAbsent || txt != null) {
-      final converter = $PureDefaultsTable.$converter0;
+      final converter = $PureDefaultsTable.$converter0n;
       map['insert'] = Variable<String?>(converter.toSql(txt));
     }
     return map;
@@ -1270,7 +1270,7 @@ class PureDefault extends DataClass implements Insertable<PureDefault> {
       {ValueSerializer? serializer}) {
     serializer ??= driftRuntimeOptions.defaultSerializer;
     return PureDefault(
-      txt: $PureDefaultsTable.$converter0
+      txt: $PureDefaultsTable.$converter0n
           .fromJson(serializer.fromJson<String?>(json['txt'])),
     );
   }
@@ -1284,7 +1284,7 @@ class PureDefault extends DataClass implements Insertable<PureDefault> {
     serializer ??= driftRuntimeOptions.defaultSerializer;
     return <String, dynamic>{
       'txt': serializer
-          .toJson<String?>($PureDefaultsTable.$converter0.toJson(txt)),
+          .toJson<String?>($PureDefaultsTable.$converter0n.toJson(txt)),
     };
   }
 
@@ -1333,7 +1333,7 @@ class PureDefaultsCompanion extends UpdateCompanion<PureDefault> {
   Map<String, Expression> toColumns(bool nullToAbsent) {
     final map = <String, Expression>{};
     if (txt.present) {
-      final converter = $PureDefaultsTable.$converter0;
+      final converter = $PureDefaultsTable.$converter0n;
       map['insert'] = Variable<String?>(converter.toSql(txt.value));
     }
     return map;
@@ -1359,7 +1359,7 @@ class $PureDefaultsTable extends PureDefaults
   late final GeneratedColumnWithTypeConverter<MyCustomObject?, String?> txt =
       GeneratedColumn<String?>('insert', aliasedName, true,
               type: const StringType(), requiredDuringInsert: false)
-          .withConverter<MyCustomObject?>($PureDefaultsTable.$converter0);
+          .withConverter<MyCustomObject?>($PureDefaultsTable.$converter0n);
   @override
   List<GeneratedColumn> get $columns => [txt];
   @override
@@ -1388,8 +1388,10 @@ class $PureDefaultsTable extends PureDefaults
     return $PureDefaultsTable(attachedDatabase, alias);
   }
 
-  static JsonTypeConverter<MyCustomObject?, String?> $converter0 =
+  static JsonTypeConverter<MyCustomObject, String> $converter0 =
-      JsonTypeConverter.asNullable(const CustomJsonConverter());
+      const CustomJsonConverter();
+  static JsonTypeConverter<MyCustomObject?, String?> $converter0n =
+      JsonTypeConverter.asNullable($converter0);
 }
 
 class CategoryTodoCountViewData extends DataClass {
@@ -1689,7 +1691,7 @@ abstract class _$TodoDb extends GeneratedDatabase {
         readsFrom: {
           tableWithoutPK,
         }).map((QueryRow row) =>
-        $TableWithoutPKTable.$converter0.fromSql(row.read<String>('custom'))!);
+        $TableWithoutPKTable.$converter0.fromSql(row.read<String>('custom')));
   }
 
   @override

drift_dev/lib/src/analyzer/dart_types.dart

@@ -135,16 +135,15 @@ UsedTypeConverter? readTypeConverter(
   final appliesToJsonToo = helper.isJsonAwareTypeConverter(staticType, library);
 
   // Make the type converter support nulls by just mapping null to null if this
-  // converter is otherwise non-nullable in both directions but applied on a
+  // converter is otherwise non-nullable in both directions.
-  // nullable column
+  final canBeSkippedForNulls = !dartTypeNullable && !sqlTypeNullable;
-  final skipForNull = !dartTypeNullable && !sqlTypeNullable && columnIsNullable;
 
   if (sqlTypeNullable != columnIsNullable) {
     if (!columnIsNullable) {
       reportError('This column is non-nullable in the database, but has a '
           'type converter with a nullable SQL type, meaning that it may '
           "potentially map to `null` which can't be stored in the database.");
-    } else if (!skipForNull) {
+    } else if (!canBeSkippedForNulls) {
       final alternative = appliesToJsonToo
           ? 'JsonTypeConverter.asNullable'
           : 'NullAwareTypeConverter.wrap';
@@ -156,7 +155,7 @@ UsedTypeConverter? readTypeConverter(
     }
   }
 
-  _checkType(columnType, null, sqlType, library.typeProvider,
+  _checkType(columnType, columnIsNullable, null, sqlType, library.typeProvider,
       library.typeSystem, reportError);
 
   return UsedTypeConverter(
@@ -166,7 +165,7 @@ UsedTypeConverter? readTypeConverter(
     dartTypeIsNullable: dartTypeNullable,
     sqlTypeIsNullable: sqlTypeNullable,
     alsoAppliesToJsonConversion: appliesToJsonToo,
-    skipForNulls: skipForNull,
+    canBeSkippedForNulls: canBeSkippedForNulls,
   );
 }
 
@@ -184,7 +183,7 @@ void _checkParameterType(
   }
 
   final nullableDartType = column.typeConverter != null
-      ? column.typeConverter!.mapsToNullableDart
+      ? column.typeConverter!.mapsToNullableDart(column.nullable)
       : column.nullableInDart;
 
   if (library.isNonNullableByDefault &&
@@ -197,6 +196,7 @@ void _checkParameterType(
 
   _checkType(
     column.type,
+    column.nullable,
     column.typeConverter,
     element.type,
     library.typeProvider,
@@ -207,6 +207,7 @@ void _checkParameterType(
 
 void _checkType(
   ColumnType columnType,
+  bool columnIsNullable,
   UsedTypeConverter? typeConverter,
   DartType typeToCheck,
   TypeProvider typeProvider,
@@ -216,7 +217,7 @@ void _checkType(
   DriftDartType expectedDartType;
   if (typeConverter != null) {
     expectedDartType = typeConverter.dartType;
-    if (typeConverter.skipForNulls) {
+    if (typeConverter.canBeSkippedForNulls && columnIsNullable) {
       typeToCheck = typeSystem.promoteToNonNull(typeToCheck);
     }
   } else {

drift_dev/lib/src/model/types.dart

@@ -75,7 +75,8 @@ class DriftDartType {
 extension OperationOnTypes on HasType {
   /// Whether this type is nullable in Dart
   bool get nullableInDart {
-    return (nullable && !isArray) || typeConverter?.mapsToNullableDart == true;
+    return (nullable && !isArray) ||
+        typeConverter?.mapsToNullableDart(nullable) == true;
   }
 
   /// the Dart type of this column that can be handled by moors type mapping.
@@ -111,7 +112,7 @@ extension OperationOnTypes on HasType {
     final converter = typeConverter;
     if (converter != null) {
       var inner = converter.dartType.codeString(options);
-      if (converter.skipForNulls) inner += '?';
+      if (converter.canBeSkippedForNulls && nullable) inner += '?';
       return isArray ? 'List<$inner>' : inner;
     }
 

drift_dev/lib/src/model/used_type_converter.dart

@@ -46,22 +46,36 @@ class UsedTypeConverter {
   /// serialization.
   final bool alsoAppliesToJsonConversion;
 
-  /// Whether this type converter should be skipped for `null` values.
+  /// Whether this type converter can be skipped for `null` values.
   ///
   /// This applies to type converters with a non-nullable Dart and SQL type if
   /// the column is nullable. For those converters, drift maps `null` to `null`
   /// without calling the type converter at all.
   ///
-  /// This is implemented by wrapping it in a `NullAwareTypeConverter` in the
+  /// For nullable columns, this is implemented by wrapping it in a
-  /// generated code.
+  /// `NullAwareTypeConverter` in the generated code for table classes. For
-  final bool skipForNulls;
+  /// nullable references to non-nullable columns (e.g. from outer joins), this
+  /// is done with static helper methods on `NullAwareTypeConverter`.
+  final bool canBeSkippedForNulls;
 
   /// Type converters are stored as static fields in the table that created
   /// them. This will be the field name for this converter.
   String get fieldName => '\$converter$index';
 
+  /// If this converter [canBeSkippedForNulls] and is applied to a nullable
+  /// column, drift generates a new wrapped type converter which will deal with
+  /// `null` values.
+  /// That converter is stored in this field.
+  String get nullableFieldName => '${fieldName}n';
+
   /// A Dart expression resolving to this converter.
-  String get tableAndField => '${table!.entityInfoName}.$fieldName';
+  String tableAndField({bool forNullableColumn = false}) {
+    final field = canBeSkippedForNulls && forNullableColumn
+        ? nullableFieldName
+        : fieldName;
+
+    return '${table!.entityInfoName}.$field';
+  }
 
   UsedTypeConverter({
     required this.expression,
@@ -70,7 +84,7 @@ class UsedTypeConverter {
     required this.dartTypeIsNullable,
     required this.sqlTypeIsNullable,
     this.alsoAppliesToJsonConversion = false,
-    this.skipForNulls = false,
+    this.canBeSkippedForNulls = false,
   });
 
   factory UsedTypeConverter.forEnumColumn(
@@ -114,24 +128,27 @@ class UsedTypeConverter {
     );
   }
 
-  bool get mapsToNullableDart => dartTypeIsNullable || skipForNulls;
+  bool mapsToNullableDart(bool nullableInSql) {
+    return dartTypeIsNullable || (canBeSkippedForNulls && nullableInSql);
+  }
 
-  String dartTypeCode(GenerationOptions options) {
+  String dartTypeCode(GenerationOptions options, bool nullableInSql) {
     var type = dartType.codeString(options);
-    if (options.nnbd && skipForNulls) type += '?';
+    if (options.nnbd && (canBeSkippedForNulls && nullableInSql)) type += '?';
 
     return type;
   }
 
   /// A suitable typename to store an instance of the type converter used here.
-  String converterNameInCode(GenerationOptions options) {
+  String converterNameInCode(GenerationOptions options,
+      {bool makeNullable = false}) {
     var sqlDartType = sqlType.getDisplayString(withNullability: options.nnbd);
-    if (options.nnbd && skipForNulls) sqlDartType += '?';
+    if (makeNullable) sqlDartType += '?';
 
     final className =
         alsoAppliesToJsonConversion ? 'JsonTypeConverter' : 'TypeConverter';
 
-    return '$className<${dartTypeCode(options)}, $sqlDartType>';
+    return '$className<${dartTypeCode(options, makeNullable)}, $sqlDartType>';
   }
 }
 

drift_dev/lib/src/writer/queries/query_writer.dart

@@ -182,13 +182,18 @@ class QueryWriter {
     final dartLiteral = asDartLiteral(specialName ?? column.name);
     var code = 'row.read<$rawDartType>($dartLiteral)';
 
-    if (column.typeConverter != null) {
+    final converter = column.typeConverter;
-      final nullableDartType = column.typeConverter!.mapsToNullableDart;
+    if (converter != null) {
-      final needsAssert = !nullableDartType && generationOptions.nnbd;
+      if (converter.canBeSkippedForNulls && column.nullable) {
-
+        // The type converter maps non-nullable types, but the column may be
-      final converter = column.typeConverter;
+        // nullable in SQL => just map null to null and only invoke the type
-      code = '${_converter(converter!)}.fromSql($code)';
+        // converter for non-null values.
-      if (needsAssert) code += '!';
+        code = 'NullAwareTypeConverter.wrapFromSql(${_converter(converter)}, '
+            '$code)';
+      } else {
+        // Just apply the type converter directly.
+        code = '${_converter(converter)}.fromSql($code)';
+      }
     }
     return code;
   }
@@ -865,9 +870,16 @@ class _ExpandedVariableWriter {
       final buffer = StringBuffer('Variable<$type>(');
       final capture = element.forCaptured;
 
-      if (element.typeConverter != null) {
+      final converter = element.typeConverter;
-        // Apply the converter
+      if (converter != null) {
-        buffer.write('${_converter(element.typeConverter!)}.toSql($dartExpr)');
+        // Apply the converter.
+        if (element.nullable && converter.canBeSkippedForNulls) {
+          buffer.write('NullAwareTypeConverter.wrapToSql('
+              '${_converter(element.typeConverter!)}, $dartExpr)');
+        } else {
+          buffer
+              .write('${_converter(element.typeConverter!)}.toSql($dartExpr)');
+        }
 
         final needsNullAssertion =
             !element.nullable && scope.generationOptions.nnbd;

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

@@ -59,7 +59,7 @@ class DataClassWriter {
       ..write('({')
       ..write(columns.map((column) {
         final nullableDartType = column.typeConverter != null
-            ? column.typeConverter!.mapsToNullableDart
+            ? column.typeConverter!.mapsToNullableDart(column.nullable)
             : column.nullable;
 
         if (nullableDartType) {
@@ -143,10 +143,11 @@ class DataClassWriter {
       if (typeConverter != null && typeConverter.alsoAppliesToJsonConversion) {
         final type = column.innerColumnType(scope.generationOptions);
         final fromConverter = "serializer.fromJson<$type>(json['$jsonKey'])";
+        final converterField =
+            typeConverter.tableAndField(forNullableColumn: column.nullable);
         final notNull =
             !column.nullable && scope.generationOptions.nnbd ? '!' : '';
-        deserialized =
+        deserialized = '$converterField.fromJson($fromConverter)$notNull';
-            '${typeConverter.tableAndField}.fromJson($fromConverter)$notNull';
       } else {
         final type = column.dartTypeCode(scope.generationOptions);
 
@@ -183,7 +184,9 @@ class DataClassWriter {
 
       final typeConverter = column.typeConverter;
       if (typeConverter != null && typeConverter.alsoAppliesToJsonConversion) {
-        value = '${typeConverter.tableAndField}.toJson($value)';
+        final converterField =
+            typeConverter.tableAndField(forNullableColumn: column.nullable);
+        value = '$converterField.toJson($value)';
         dartType = '${column.innerColumnType(scope.generationOptions)}';
       }
 
@@ -268,14 +271,13 @@ class DataClassWriter {
       if (column.typeConverter != null) {
         // apply type converter before writing the variable
         final converter = column.typeConverter;
-        final fieldName = converter!.tableAndField;
+        final fieldName =
-        final assertNotNull = !column.nullable && scope.generationOptions.nnbd;
+            converter!.tableAndField(forNullableColumn: column.nullable);
 
         _buffer
           ..write('final converter = $fieldName;\n')
           ..write(mapSetter)
           ..write('(converter.toSql(${column.dartGetterName})');
-        if (assertNotNull) _buffer.write('!');
         _buffer.write(');');
       } else {
         // no type converter. Write variable directly
@@ -375,9 +377,8 @@ class RowMappingWriter {
       // result.
       if (column.typeConverter != null) {
         // stored as a static field
-        final converter = column.typeConverter!;
+        final loaded = column.typeConverter!
-        final loaded =
+            .tableAndField(forNullableColumn: column.nullable);
-            '${converter.table!.entityInfoName}.${converter.fieldName}';
         loadType = '$loaded.fromSql($loadType)';
       }
 

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

@@ -100,14 +100,17 @@ abstract class TableOrViewWriter {
     if (converter != null) {
       // Generate a GeneratedColumnWithTypeConverter instance, as it has
       // additional methods to check for equality against a mapped value.
-      final mappedType = converter.dartTypeCode(options);
+      final mappedType = converter.dartTypeCode(options, column.nullable);
+
+      final converterCode =
+          converter.tableAndField(forNullableColumn: column.nullable);
 
       type = 'GeneratedColumnWithTypeConverter<$mappedType, $innerType>';
       expressionBuffer
         ..write('.withConverter<')
         ..write(mappedType)
         ..write('>(')
-        ..write(converter.tableAndField)
+        ..write(converterCode)
         ..write(')');
     }
 
@@ -311,18 +314,32 @@ class TableWriter extends TableOrViewWriter {
   void _writeConvertersAsStaticFields() {
     for (final converter in table.converters) {
       final typeName = converter.converterNameInCode(scope.generationOptions);
-      var code = converter.expression;
+      final code = converter.expression;
-
-      if (converter.skipForNulls) {
-        if (converter.alsoAppliesToJsonConversion) {
-          code = 'JsonTypeConverter.asNullable($code)';
-        } else {
-          code = 'NullAwareTypeConverter.wrap($code)';
-        }
-      }
 
       buffer.write('static $typeName ${converter.fieldName} = $code;');
     }
+
+    // Generate wrappers for non-nullable type converters that are applied to
+    // nullable converters.
+    for (final column in table.columns) {
+      final converter = column.typeConverter;
+      if (converter != null &&
+          converter.canBeSkippedForNulls &&
+          column.nullable) {
+        final nullableTypeName = converter
+            .converterNameInCode(scope.generationOptions, makeNullable: true);
+
+        final wrap = converter.alsoAppliesToJsonConversion
+            ? 'JsonTypeConverter.asNullable'
+            : 'NullAwareTypeConverter.wrap';
+
+        final code = '$wrap(${converter.fieldName})';
+
+        buffer
+            .write('static $nullableTypeName ${converter.nullableFieldName} = '
+                '$code;');
+      }
+    }
   }
 
   void _writeColumnVerificationMeta(MoorColumn column) {

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

@@ -188,16 +188,13 @@ class UpdateCompanionWriter {
       final converter = column.typeConverter;
       if (converter != null) {
         // apply type converter before writing the variable
-        final fieldName = '${table.entityInfoName}.${converter.fieldName}';
+        final fieldName =
+            converter.tableAndField(forNullableColumn: column.nullable);
         _buffer
           ..write('final converter = $fieldName;\n')
           ..write(mapSetter)
-          ..write('(converter.toSql($getterName.value)');
+          ..write('(converter.toSql($getterName.value)')
-
+          ..write(');');
-        if (!column.nullable && scope.generationOptions.nnbd) {
-          _buffer.write('!');
-        }
-        _buffer.write(');');
       } else {
         // no type converter. Write variable directly
         _buffer

drift_dev/test/analyzer/dart/type_converter_test.dart

@@ -94,7 +94,7 @@ CREATE TABLE users (
     );
 
     final implicitlyNullAware = table.columns[3];
-    expect(implicitlyNullAware.typeConverter?.skipForNulls, isTrue);
+    expect(implicitlyNullAware.typeConverter?.canBeSkippedForNulls, isTrue);
   });
 
   test('json converters in drift files', () {

examples/app/lib/database/database.g.dart

@@ -20,7 +20,7 @@ class Category extends DataClass implements Insertable<Category> {
       name: const StringType()
           .mapFromDatabaseResponse(data['${effectivePrefix}name'])!,
       color: $CategoriesTable.$converter0.fromSql(const IntType()
-          .mapFromDatabaseResponse(data['${effectivePrefix}color']))!,
+          .mapFromDatabaseResponse(data['${effectivePrefix}color'])!),
     );
   }
   @override
@@ -30,7 +30,7 @@ class Category extends DataClass implements Insertable<Category> {
     map['name'] = Variable<String>(name);
     {
       final converter = $CategoriesTable.$converter0;
-      map['color'] = Variable<int>(converter.toSql(color)!);
+      map['color'] = Variable<int>(converter.toSql(color));
     }
     return map;
   }
@@ -135,7 +135,7 @@ class CategoriesCompanion extends UpdateCompanion<Category> {
     }
     if (color.present) {
       final converter = $CategoriesTable.$converter0;
-      map['color'] = Variable<int>(converter.toSql(color.value)!);
+      map['color'] = Variable<int>(converter.toSql(color.value));
     }
     return map;
   }
@@ -646,7 +646,8 @@ abstract class _$AppDatabase extends GeneratedDatabase {
       return CategoriesWithCountResult(
         id: row.read<int?>('id'),
         name: row.read<String?>('name'),
-        color: $CategoriesTable.$converter0.fromSql(row.read<int?>('color')),
+        color: NullAwareTypeConverter.wrapFromSql(
+            $CategoriesTable.$converter0, row.read<int?>('color')),
         amount: row.read<int>('amount'),
       );
     });

examples/app/lib/database/tables.dart

@@ -35,12 +35,12 @@ mixin AutoIncrementingPrimaryKey on Table {
   IntColumn get id => integer().autoIncrement()();
 }
 
-class ColorConverter extends NullAwareTypeConverter<Color, int> {
+class ColorConverter extends TypeConverter<Color, int> {
   const ColorConverter();
 
   @override
-  Color requireFromSql(int fromDb) => Color(fromDb);
+  Color fromSql(int fromDb) => Color(fromDb);
 
   @override
-  int requireToSql(Color value) => value.value;
+  int toSql(Color value) => value.value;
 }