How to use appendobjectfields

[Ramakant2021]

I am trying to add a new field to an existing schema with appendobjectfields (). The problem I am facing is it is not resolving the field when I do the query. This is error mesage I receive: '"message": "Cannot query field "newField" on type "Product".",'

Here is my code. Where I am going wrong.

export class ProjectionSchemaWrap {
    typeName: string = "String";
    fieldName: string = "newField";
    private readonly resolver: GraphQLFieldResolver<any, any>;

  transformSchema(schema: GraphQLSchema) {
    
    const QueryType = schema.getQueryType();
    const queryConfig = QueryType.toConfig();

    const nestedQuery = new GraphQLObjectType({
      ...queryConfig,
      name: this.typeName,
    });
     
    const newRootFieldConfigMap: GraphQLFieldConfigMap<any, any> = {
      [this.fieldName]: {
        type: new GraphQLNonNull(nestedQuery),
        resolve: (parent, args, context) => {
          if (this.resolver != null) {
            console.log("Resolver is not null");
            return "10";
          }
          return "11";
        },
      },
    };

    schema = appendObjectFields(schema, "Product", newRootFieldConfigMap);
    return schema;

  }
}
export class ProjectionTransformHelper implements MeshTransform {
  noWrap = true;
  private config: ProjectionTransform;
  private baseDir: string;
  typeName: string = "String";
  fieldName: string = "newField";
  graphqlFieldConfig: GraphQLFieldConfig<any,any>;
  private transforms: Transform[] = [];
  private readonly resolver: GraphQLFieldResolver<any, any>;
  fieldName1: string = "id1";
  
  constructor({ baseDir, config }: MeshTransformOptions<ProjectionTransform>) {
    this.config = config;
    this.baseDir = baseDir;

    this.transforms.push(new ProjectionSchemaWrap());
  }

  transformSchema(schema: GraphQLSchema) {
  
    return wrapSchema({
      schema: schema,
      transforms: this.transforms,
    });
    
}
}

[Ramakant2021]

Any suggestion here please