How do I check if a field already exists in the database? - mongodb

Question

My problem is about checking if the name or email of a staff already exist in the database. They say its good to do it in the pre update middleware. I tried it but it's not working.
Im passing the (id_of_staff, updatedStaff_info and callback_function) to the update function.
Here's my update function:
module.exports.updateStaff = function(id, updatedStaff, callback){
var query = {_id: id};
Staff.update(query, updatedStaff, callback);
}
Everytime the Staff.update() is called the pre update middleware is executed. What I want here is check if the name or email if they already exist. The problem is, it seems that the name and email in the pre update middleware is undefined.
My pre update middleware:
staffSchema.pre("update", function(next){
var staff = this;
Staff.find({_id:{$ne: staff.id}, $or:[{name: staff.name}, {email: staff.email}]}, function (err, docs) {
if (!docs.length){
next();
}else{
next(new Error("Name or email already exist"));
}
});
});
The result that I got is always "Name or email already exist". And I tried to print in the console log the value of staff.name but it says its undefined. Am I doing it right? Can you help me to get it working. Thank you very much guys.

Answer 1

I found a solution to my question. Instead of using pre update middleware, I just create a function to check if the name or email already exist.
Here's the code:
module.exports.updateStaff = function(id, updatedStaff, callback){
var query = {_id: id};
//check name and email if already available
function updateStaff(id, updatedStaff, callback){
//get staff that has the same name or email
Staff.find({_id:{$ne:id}, $or:[{name: updatedStaff.name}, {email_pc: updatedStaff.email_pc}]}).exec(
function(err, result){
console.log(result);
if(!err){
if(result.length){
console.log("Name or email already exist.");
callback("Conflict", null);
}
else{
//udpate the staff
Staff.update(query, updatedStaff, callback);
}
}else{
callback(err);
}
})
}
updateStaff(id, updatedStaff, callback);
}
But I'm still open to answer using pre update middleware. Thanks :)