removing object id from an array not working in mongoose

Question

I am trying to remove logged-in users objectId from an array field called interest but it doesnt work.

model

const projectSchema = new mongoose.Schema({
    owner: {
        type: mongoose.Schema.Types.ObjectId,
        required: true,
        ref: 'User'
    },
    isShowcase: {
        type: Boolean,
        required: false,
        default: false
    },
    isCollab: {
        type: Boolean,
        required: false,
        default: false
    },
    title: {
        type: String,
        required: true,
        trim: true
    },
    description: {
        type: String,
        required: true,
        trim: true
    },
    thumbnail: {
        type: String,
        required: true,
        trim: true
    },
    media: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Media',
        required: false,
    }],
    skillsNeeded: [{
        type: mongoose.Schema.Types.ObjectId,
        required: false,
        ref: 'Skill'
    }],
    contributors: [{
        user: {
            type: mongoose.Schema.Types.ObjectId,
            required: false,
            ref: 'User'
        },
        role: {
            type: mongoose.Schema.Types.ObjectId,
            required: false,
            ref: 'Skill'
        },
        required: false,
    }],
    isOpen: {
        type: Boolean,
        required: false,
        default: false
    },
    interest: [{
        type: mongoose.Schema.Types.ObjectId,
        required: false,
        ref: 'User'
    }]
}, {
    timestamps: true
})

the route to remove interest

// delete an interest on a collaboration
router.delete('/api/project/:id/apply', auth, async (req, res) => {
    const project = await Project.findOne({ _id: req.params.id, isOpen: true })

    if (!project) {
        res.status(500).send({ "message": "you cannot show interest at the moment" })
    }

    try {
        project.interest = project.interest.filter((objid) => {
            return objid != req.user._id
        })
        await project.save()
        console.log(project);
        return res.status(204).send(project)
    } catch (e) {
        res.status(500).send()
    }
})

below is the project I am trying to remove a users object id from the interest

{
    "isShowcase": false,
    "isCollab": true,
    "media": [],
    "skillsNeeded": [
        "5f9fc49a0282a127e4aca0fa",
        "5faa596e9d54a92ab805a7a9"
    ],
    "isOpen": true,
    "interest": [
        "5fa35ac783fe7042fcbbf12a"
    ],
    "_id": "5fb98a36cc3b62aa788adbe0",
    "title": "American gods",
    "description": "it a story about a war between new and old gods",
    "thumbnail": "https://images-na.ssl-images-amazon.com/images/S/pv-target-images/fc3ef790bcbc143d2b5b76b454b7cdcc68a19d60f629e328121713590294a895._RI_V_TTW_.jpg",
    "owner": "5fa4f0af4a7bf5471c41e225",
    "contributors": [],
    "createdAt": "2020-11-21T21:44:22.818Z",
    "updatedAt": "2020-11-22T08:22:02.377Z",
    "__v": 1
}

when I run the delete request to that route, I get status 204 but the project is not returned, and when I check back on the project, I still see the project with the user's objectID still in the array.

the logged-in users object

{
    "skills": [],
    "isEmailConfirmed": false,
    "isAdmin": false,
    "isActive": true,
    "hasSpecialPrevilege": false,
    "_id": "5fa35ac783fe7042fcbbf12a",
    "fullname": "olayinka odedeyi",
    "username": "yinkus",
    "email": "olayinkaodedeyi@gmail.com",
    "createdAt": "2020-11-05T01:52:07.378Z",
    "updatedAt": "2020-11-22T10:37:08.307Z",
    "__v": 4,
    "bio": "a great girl"
}

Please, what could be preventing the logged-in user id from getting removed when the delete route to do that is run?

Answer 1

The problem lies in how you are comparing the two objectids in filter function. You need to use .equals() method available on objectId instance.

project.interest = project.interest.filter((objid) => {
            return !objid.equals(req.user._id)
        })