CODEWITHSUNDEEP
javascriptnode.jsmongodbexpressmongoose
Captain Nigorro
Captain Nigorro

Reputation: 45

Nodejs and Mongoose data fetching

I have some problem with data fetching.

I have mongoose scheme.

PostSchema.methods.getAuthor = function () {
    this.model('User').findById(this.author).exec(function (err, author){
        if (author) {
            console.log(author.username);
            return author.username;
        };
    });
};

mongoose.model('Post', PostSchema);

and getMethod

exports.getPost = function (req, res) {
    return Post.findById(req.params.id, function (err, post) {
        if (!post) {
            res.statusCode = 404;
            return res.send({ error: 'Not found' });
        }
        if (!err) {
            var author = post.getAuthor();
            console.log('author is: ', author);

            return res.send({ status: 'OK', post:post });
        } else {
            res.statusCode = 500;
            return res.send({ error: 'Server error' });
        }
    });
};

When I call post.getAuthor() inside getPost method he is work and found User by Id. But var author = post.getAuthor(); have undefined value.

Upvotes: 3

Views: 141

Answers (1)

Andrew Lavers
Andrew Lavers

Reputation: 8151

As @zaynetro mentioned you're calling your getAuthor method incorrectly. It's an asynchronous method, so you should be accepting a callback parameter, or you could return a promise.

But what you're trying to do is already built in to mongoose, its called query population.

http://mongoosejs.com/docs/populate.html

You can configure a Post.author reference property that you can have mongoose resolve into the document for you.

var postSchema = Schema({
    author: {
        type: Schema.Types.ObjectId,
        ref: 'User'
    }
});
mongoose.model('Post', postSchema);

var userSchma = Schema({
    name: String
});
mongoose.model('User', userSchema);

Then, in your route your query would look like this:

Post
    .findById(req.params.id)
    .populate('author')
    .exec(function(err, post) {
        if (err) {
            return res.status(500).send({
                error: 'Server error'
            });
        }
        // post.author contains the content of your author document
        return res.send(post);
    });

Upvotes: 3

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