Mongoosejs find on array of objectId

Question

I am struggling with this since few hours now and hence posting here. I am trying to use find() operator in mongoose, to find whether a key matches any single element in the array, similar to How do I perform an id array query in Mongoose? but not getting expected results.

Here is my schema,

var a = new mongoose.Schema({
    b : { type : mongoose.Schema.ObjectId, ref: 'B' },
});

var A = mongoose.model('A', a);

now I have an array , arr[], which holds some possible object id's of class B. i.e

arr = ["54e545fb6a0d90bb0772808b", "xxxxxxxxxxxxx", ...]

I want to find all documents of type A, where the field b matches any of the elements in arr. Note that arr is an array of strings, but b holds ObjectId.

So far I have tried,

A.find({b : {$in: arr}}, callback); //and
A.find({b : {$in: new ObjectId("54e545fb6a0d90bb0772808b")}}, callback); //manually got this one value from db

var callback = function (err, data) {
        console.log("----------------------");
        if (err)
            console.log(err);
        else {
            console.log(JSON.stringify(data, null, '\t'));
        }
        console.log("----------------------");

    }

Both of these does not seem to work. Thank you for the help.

Yuri Zarubin · Accepted Answer · 2015-02-19 04:02:44Z

12

Assuming arr is an array of strings representing ObjectId:

A.find({b : {
  $in: arr.map(function(o){ return mongoose.Types.ObjectId(o); })
}}, callback);

answered Feb 19, 2015 at 4:02

Yuri Zarubin

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3 Comments

Anoop Over a year ago

This still does not fetch any results. It returns an empty array

wdberkeley Over a year ago

This looks like correct syntax. Are you sure an A with the right B _id's in its array exists in the collection? What happens if you try a similar query in the mongo shell?

Anoop Over a year ago

Ah..sorry. . this works. Turns out infact I was using the wrong id. Pardon my ignorance. Actually we need not even convert to ObjectId for it to work.

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