Res.send proceed before Function Model.find() Nodejs

I got the problem when trying to find the value throw 2 model

.get(function(req, res) {
        var sellerPosts = [];
        Product.find({seller_id : req.params.seller_id}, function(err, products) {
            if (err) throw err;
            for (var i = 0; i < products.length; i++) {
                console.log("id", products[i].id);
                Post.find({product_id : products[i].id}, function(err, posts) {
                    if (err) throw err;
                    for (var j = 0; j < posts.length; j++) {
                        sellerPosts.push(posts[j]);
                        console.log("in find",sellerPosts);

                    }
                });
                console.log(sellerPosts);
            }
            console.log("test", sellerPosts);

            res.send(sellerPosts);
        });

    })

The first sellerPosts still print out true values but the "test" log is empty. After doing some log. I think it is because after the first for in Product.find(), the program run the res.send and then run the Post.find(). Help me on fixing this problem please!!!!

via Tung Mai