I have a class Template
with a property _id
which has decorators from class-transformer
and typed-graphql
import {classToPlain, Exclude, Expose, plainToClass, Type } from 'class-transformer';
import { ExposeToGraphQL } from '../../decorators/exposeToGraphQL';
import { Field, ID, MiddlewareInterface, NextFn, ObjectType, ResolverData } from 'type-graphql';
import { getClassForDocument, InstanceType, prop, Typegoose } from 'typegoose';
/**
* Class
* @extends Typegoose
*/
@Exclude()
@ObjectType()
class Template extends Typegoose {
// @Expose and @Type should be both covered by ExposeToGraphQL
// @Expose()
@Type(() => String)
@ExposeToGraphQL()
@Field(() => ID)
public _id?: mongoose.Types.ObjectId;
}
Now I try to combine those two into a new custom property decorator:
/**
*
*/
import { Expose } from 'class-transformer';
import 'reflect-metadata';
const formatMetadataKey: Symbol = Symbol('ExposeToGraphQL');
function ExposeToGraphQL() {
console.log('ExposeToGraphQL');
return Expose();
}
function getExposeToGraphQL(target: any, propertyKey: string) {
console.log('getExposeToGraphQL');
return Reflect.getMetadata(formatMetadataKey, target, propertyKey);
}
export {
ExposeToGraphQL,
getExposeToGraphQL,
};
The custom decorator works if I only return the result of Expose()
, but I don't know how to combine @Expose
and @Type
in @ExposeToGraphQL()
.
import { Expose, Type, TypeOptions, ExposeOptions } from 'class-transformer';
/**
* Combines @Expose then @Types decorators.
* @param exposeOptions options that passes to @Expose()
* @param typeFunction options that passes to @Type()
*/
function ExposeToGraphQL(exposeOptions?: ExposeOptions, typeFunction?: (type?: TypeOptions) => Function) {
const exposeFn = Expose(exposeOptions);
const typeFn = Type(typeFunction);
return function (target: any, key: string) {
typeFn(target, key);
exposeFn(target, key);
}
}
Then you can use that decorator as follow:
class Template extends Typegoose {
@ExposeToGraphQL(/*exposeOptions*/ undefined, /*typeFunction*/ () => String)
@Field(() => ID)
public _id?: mongoose.Types.ObjectId;
}
You can find official documentation for decorator in this link.
@Expose
and @Type()
are basically Decorator Factories. The main purpose of a decorator factory:
Template
, was defined) with 2 arguments:
Template.prototype
) _id
).If two or more decorators are attached to a same property (called as Decorator Composition), they are evaluated as follow: