Prerequisites:

Database is created already with the collections posts and it's Schema is as follows:

module.exports = function(mongoose){
var Schema = mongoose.Schema;

var postSchema = new Schema({
   postID:          String,
   title:           String,
   description:     String
});

mongoose.model('post', postSchema, 'posts');
postSchema.index({title: 'text'});

};

Node's router to handle via an API:

apiRouter.get('/api/searchPosts', function(req, res, next){
    postModel.find(
        { $text : { $search : req.query.text } }, 
        { score : { $meta: "textScore" } }
    )
    .sort({ score : { $meta : 'textScore' } })
    .exec(function(err, posts) {
        if(posts){
            res.json({
                posts       :   posts
            });
        } else {
            res.send('Post does not exist');
        }
    });
});

What I am trying to achieve:

I want to make a field in my posts table called title text searchable.

My stack:

MongoDB, NodeJS (with Mongoose), Angular

My approach:

As mentioned in the Prerequisites, I have added the line:

postSchema.index({title: 'text'});

Furthermore, I have run the below command in the terminal once the collections has been created:

db.posts.createIndex({"title":"text"})

The problem:

When I access this from the URL, it works initially but after a few weeks, it stops working (I get 'Post does not exist' without making any changes!). To get it working again, I have to delete the collections and make a fresh one and run the command:

db.posts.createIndex({"title":"text"})

It then starts working for a few weeks and so on.

What I am doing wrong? I am not seeing a trend about what happens in these few weeks. I have been stuck on this issue for a few weeks so if someone can help, it will be highly appreciated.

Thanks, Shayan