CODEWITHSUNDEEP
node.jsmongodbtypescriptmongoose
Thomas
Thomas

Reputation: 29522

Mongoose Promise with bluebird and typescript

I am developing an application with nodejs/typescript and a mongodb database. To query the database, I am using mongoose.

I've just read an article from the mongoose documentation on how to plug in an external promise library and it is very simple:

import mongoose = require("mongoose");
import Promise = require("bluebird");
mongoose.Promise = Promise;

Doing this is working fine. But I'd like to extend/override the type of the promise that is returned.

Here is an example of a function:

public getModel= () => {
    return MyModel.findOne().exec();
}

This function returns a _mongoose.Promise<MyModel> and I'd like to return a bluebird Promise<MyModel> because I know that is a bluebird promise.

Is there is anyway to change/extend/override the return type of mongoose query ? Should I write a custom definition file for my app ? Any others suggestions would be appreciated.

Thanks !

Upvotes: 6

Views: 5560

Answers (4)

Jthorpe
Jthorpe

Reputation: 10167

As of this writing, there is an open issue in the typings file that is installed if you use typings install mongoose to install the typings. Specificaly typings file that is loaded imports mpromise, and that import statement results in inclusion of the full mpromise module definition file by typings and included in your typings\modules\mongoose\index.d.ts file.

Until this issue get's resolved, my workaround is to delete the module definition for ~mongoose~mpromise and replace the following line in the index.d.ts file: 

import * as Promise from '~mongoose~mpromise';

with this one:

import Promise = require( "bluebird");

This is admittedly a temporary stop-gap as another call to typings install mongoose would revert this fix. For the curious, my current set up includes: typings ( version 2.0.0 ), npm ( 3.10.9 ), and node ( v6.9.2 )

Upvotes: 0

Thomas
Thomas

Reputation: 29522

The mongoose team updated the definition file and you can now plug in and use your own promise library by assigning the MongoosePromise<T>.

Create a main .d.ts file for your application and add this:

declare module "mongoose" {
    import Bluebird = require("bluebird");
    type MongoosePromise<T> = Bluebird<T>;
}

Reference this file in your project and now Mongoose returns Bluebird Promise !

This also works for others promises library.

EDIT latest typings version

declare module "mongoose" {
    import Bluebird = require("bluebird");
    type Promise<T> = Bluebird<T>;
}

See documentation here

Upvotes: 1

ServerYang
ServerYang

Reputation: 79

Promise export as a variable in mongoose, so you can convert mongoose namespace as any first, and then set Promise to others.

  1. if you are using q lib.
    • install npm install --save q @types/q first. tsc version >= 2.0.
    • then add (<any>mongoose).Promise = Q.Promise;
  2. using bluebird lib, add code below.
    • import Bluebird = require("bluebird");
    • (<any>mongoose).Promise = Bluebird;

Upvotes: 5

basarat
basarat

Reputation: 275867

Should I write a custom definition file for my app

Yes. It will mostly be a find and replace of Promise in the mongoose definition.

Upvotes: 1

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