@t.mongoId - what should it do?

[smolinari]

Hi,

What is the purpose of @t.mongoId? I was expecting it to return a string when used with classToPlain, but it is returning new objectId('*a mongoId here!*").

Scott

[marcj]

It will be a string. It can't return an ObjectId because we don't have such a class in our codebase. If you use mongo's official client, then this won't work, as "t.mongoId" is for deepkit/orm, not mongo's javascript driver. If you pass in an object from mongo's driver, it probably won't do anything with its type, which is what you see. What does your code look like?

[marcj]

I don't understand what you are saying. deepkit/type's mongoId does not work out of the box with all kind of libraries like Mongoose. It does not even work with Mongo's node-mongo-driver. That being said, you can certainly (and deepkit/type is designed for that) to customize the serializer to do that for you. See https://deepkit.io/documentation/type/serialization-target

    import {jsonSerializer} from '@deepkit/type';
    import {ObjectId} from 'bson';

    const mySerializer = jsonSerializer.fork('mySerializer');

    //We overwrite mongoId and correctly convert from Mongo ObjectID to string when deserializing
    mySerializer.toClass.register('objectId', (property, state) => {
        state.setContext({ObjectId: ObjectId});
        state.addSetter(`${state.accessor} instanceof ObjectId ? ${state.accessor}.toHexString() : ${state.accessor}`);
    });

    //We overwrite mongoId and correctly convert string to Mongo ObjectID when serializing
    mySerializer.fromClass.register('objectId', (property, state) => {
        state.setContext({ObjectId: ObjectId});
        state.addSetter(`${state.accessor} instanceof ObjectId ? ${state.accessor} : ObjectId.createFromHexString(${state.accessor})`);
    });

and then use this mySerializer instead of classToPlain/plainToClass (which use jsonSerializer per default):

class MyModel {
     @t.mongoId id?: string;
}

const m = new MyModel;
m.id = '507f191e810c19729de860ea';

mySerializer.for(MyModel).serialize(m); // {id: ObjectId}
mySerializer.for(MyModel).deserialize({id: new ObjectId('507f191e810c19729de860ea')); //{id: '507f191e810c19729de860ea'}

Note: that code is only from the top of my head, so no guarantee that it works or even compiles. But I hope you get the idea.

[smolinari]

Wow, that was a fast reply. I was still editing my post, and you had already replied. Thanks!

Yeah. I understand now the @t.mongoId is specialized. I guess I was a bit too optimistic. :)

I'll take you up on the override and see how it goes. Appreciate the help!

Scott

[smolinari]

@marcj - Ok. I tried your suggestion. But, I ran into type errors with jsonSerializer.fork.

I also tried just creating a new Serializer. I don't have the type issues, but then I get the same results as if nothing was overridden. If I create the new Serializer and then fork it, I also get the type errors.

Scott

[marcj]

See https://github.com/deepkit/deepkit-framework/blob/master/packages/type/tests/serializer-api.spec.ts#L91 for examples.

As I said, I've posted previously examples that are not necessarily correct. But in the tests you find working examples.

It should be

    const mySerializer = new class extends jsonSerializer.fork('mySerializer') {
    };

//or

    const mySerializer = new jsonSerializer.fork('mySerializer');

[smolinari]

Ok. That helped. Thanks so much!

I also found the logic was backwards. toClass (deserialization) should be creating the ObjectId. fromClass (serialization) the string. 😁

But, awesome stuff and all is working now as expected!

Thanks again. 👍

Scott