SailsJs Paginate concatenated list of objects

Question

I have a model that may or may not be related to another model. here is my model structure:

// Post.js
attributes: {
    sender: { model : 'user' },
}

// User.js
attributes: {
    posts: { collection: 'post', via: 'sender', dominant: true }
}

So the post model my or may not be attached to a sender. sender can either be a user or null.

I need to be able to get all of the posts that are specific to a particular user and all posts that do not have a sender. Once I have both of these I need to concatenate them. Here is the code I have to do this:

// Before this I use a native query to get a list of posts with no sender. This is "searchIds".
filterData.id = searchIds;
filterData.subject = 1;
posts = [];

        // Populate questions that were sent to all users
        Post.find()
            .where(filterData)
            .exec(function (err, response) {
                if(err) return res.serverError(err);
                // We add all of the posts with no senders to the messages array
                if (response.length > 0){
                    posts = posts.concat(response);
                }

                delete filterData.id;

                // Now we get the posts specific to this user.
                User.findOne({id:id})
                .populate('posts',{ where: filterData })
                .exec(function(err, results){
                  if(err) return res.serverError(err);
                    if (results && results.posts && results.posts.length > 0){
                        posts = posts.concat(results.posts);
                    }
                    return res.json(posts);
                });
        });

This works find and gets me an array of posts made by that specific user and all posts that do not have a sender, however what I need to do now is paginate this list. The way I would usually do it is to use the Sails/Waterline paginate method but because I am concatenating two separate DB calls together I dont know how I can do this?

Answer 1

You could just combine both queries with Waterlines or feature.

Post.find({
    or: {
        {sender: null}, // finds 'no sender' posts
        {sender: senderId} // finds posts where sender's id is senderId 
    }
})
.paginate({ page: 2, limit: 10 })
.then(function(posts) {
    return res.json(posts);
})
.catch(function(err) {
    return res.serverError(err);
})

I'm pretty sure you could even write the find query like

Post.find({sender: [null, senderId]})

and get the same result.