function shareAccess(req,res) {

    let username = req.body.username;
    let assigned_username = req.body.assigned_username;
    let category = req.body.category;

    if (!username || !assigned_username || !category) {
      res.status(400).json({success: false, message: 'Please fill in all fields'});
    } else {

    Category.findOne({ topic_cat: category }, (err, category_resp) => {
        assign_category = category_resp;
    }).then((category) => {
    User.findOne({'local.username' : username}, (err, user) => {
        own_user = user;
      })
    }).then(() => {
     User.findOne({'local.username' : assigned_username}, (err, user) => {
        assign_user = user;
      })
    }).then(() => {
    return Notes
        .find()
        .populate('cat')
        .populate('owner')
        .exec().then( resp => {
            let query = { owner : own_user._id , cat : assign_category._id};
            return Notes.update(query,{$push: {has_access : assign_user._id}},{multi: true}, (err, result) => {
                 event.emit('share access', assigned_username);
            })
        })
    })

    .then(() => {
    res.status(200).json({success: true, message: 'You have set a private access'});
  }).catch((e) => {
    res.status(400).json({success: false, message: 'Failed to create', error: e.message});
    })
  }
}