Question

45

Mongoose TypeScript ObjectId casting - Type 'string' is not assignable to type 'Condition< ObjectId | undefined>'

rated 0 times [ 51] [ 6] / answers: 1 / hits: 13944 / 3 Years ago, fri, october 1, 2021, 12:00:00

I am having issues with mongoose queries when I query by an ObjectId field. Passing mongoose.Types.ObjectId or string both throws errors. TypeScript only stops complaining when I cast the ObjectId to mongoose.Schema.Types.ObjectId, which then crashes at runtime since it's not a valid ObjectId.

interface DocumentWithTimestamp extends Document<ObjectId> {

  createdAt: Date;

  updatedAt: Date;

}

First of all, I noticed that Document defines _id as ObjectId | undefined, which already complicates everything.

I define my Schemas as follows:

export interface LanguageSchema extends DocumentWithTimestamp {

  langCode: string;

  locale: string;

}





interface LanguageModel extends Model<LanguageSchema> {

  mapToLanguage(language: LeanDocument<LanguageSchema> | LanguageSchema): Language;

}



const languageSchema = new Schema<LanguageSchema, LanguageModel>(

  {

    langCode: { type: String, required: true, trim: true },

    locale: { type: String, unique: true, required: true, trim: true },

  },

  { collection: 'language', timestamps: true, versionKey: false },

);



languageSchema.statics.mapToLanguage = function (language: LeanDocument<LanguageSchema> | LanguageSchema): Language {

  return {

    id: language._id?.toString() || '', // why is _id conditional...?

    langCode: language.langCode,

    locale: language.locale,

  };

};



export const LanguageModel = model<LanguageSchema, LanguageModel>('Language', languageSchema);

Now querying my LanguageModel by _id or any other ObjectId field throws type errors:

export async function findLanguagesByIds(languageIds: string[]) {

  return LanguageModel.find({ _id: { $in: languageIds } }).lean();

}

Error:

Argument of type '{ _id: { $in: string[]; }; }' is not assignable to parameter of type 'Callback<LanguageSchema[]>'.

      Object literal may only specify known properties, and '_id' does not exist in type 'Callback<LanguageSchema[]>'.

When I try to cast string[] to Schema.Types.ObjectId[] array, the error goes away but this cannot be the solution, since it crashes at runtime (Schema.Types.ObjectId is not a valid ObjectId).

const languages = await LanguageModel.find({

  _id: { $in: languageIds.map((id) => new mongoose.Schema.Types.ObjectId(id)) },

}).lean();

If I cast to mongoose.Types.ObjectId(to a real ObjectId) it throws errors again...

Any help is appreciated!

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brodyfrancisi

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answered 3 Years ago briarc · Accepted Answer

I found the solution to my problem.

mongoose Document is defined as follows:

class Document<T = any, TQueryHelpers = any, DocType = any> {

  constructor(doc?: any);



  /** This documents _id. */

  _id?: T;



  // ...

  }

I extended it using Document<ObjectId>. The ObjectId type however was the Schema type, e.g.

import { ObjectId } from "mongoose";

But it actually should have been the actual ObjectId Type of mongoose and not the Schema type!

FIX:

import { Types } from "mongoose"



interface DocumentWithTimestamp extends Document<Types.ObjectId> {

  createdAt: Date;

  updatedAt: Date;

}