generateUnions method

String generateUnions(Iterable<Field> fields)

Implementation

String generateUnions(Iterable<Field> fields) {
  final result = StringBuffer();
  final unionFields = fields.whereType<UnionField>();

  for (final field in unionFields) {
    result.writeln();
    final targetFields = fields.where((it) => it.jsonName == field.union);

    if (targetFields.isEmpty) {
      throw StateError(
          'Couldn\'t find union field in shceme "${field.union}" for "${field.jsonName}" field');
    }

    final targetField = targetFields.first;

    result.writeln(
      '  static ${field.type.displayName} _\$createUnion\$${field.name}(Map<String, dynamic> json) {',
    );
    result.writeln(
      '    final union = ' +
          _jsonGetter(targetField.type, targetField.jsonName, 'json') +
          '.toString();',
    );

    final contentType = field.type.isOptional
        ? parseType('Map<String, dynamic>?')
        : parseType('Map<String, dynamic>');

    result
        .writeln('    final content = ' + _jsonGetter(contentType, field.jsonName, 'json') + ';');
    result.writeln();
    result.write('    ');

    for (final value in field.unionValues) {
      result.writeln('if (union == \'${value.value}\') {');
      if (contentType.isOptional) {
        result.writeln('      return ${value.type.displayName}.fromJson(content ?? {});');
      } else {
        result.writeln('      return ${value.type.displayName}.fromJson(content);');
      }
      result.write('    } else ');
    }

    result.writeln('{');

    if (field.type.isOptional) {
      result.writeln('      return null;');
    } else {
      final supportedTypes = field.unionValues.map((it) => it.value).join(',');
      result.writeln(
        '      throw SchemeConsistencyException(\'Unsupported "${field.union}" value: \$union. Supported values: $supportedTypes\');',
      );
    }
    result.writeln('    }');

    result.writeln('  }');
  }

  return result.toString();
}