如何在Mongoose中添加收藏？

Question

I'm trying to clear my Users collection before and after my tests:

before(function(done) {
  mongoose.connection.collections['users'].drop(function(err) {
    mongoose.connection.collections['users'].insert(user, done);
  });
});

after(function(done) {
  mongoose.connection.collections['users'].drop(done);
});

I also tried it without the drop in the before :

before(function(done) {
  // mongoose.connection.collections['users'].drop(function(err) {
    mongoose.connection.collections['users'].insert(user, done);
  // });
});


after(function(done) {
  mongoose.connection.collections['users'].drop(done);
});

I'm getting these errors:

1) Auth API "before all" hook:
     TypeError: Cannot read property 'drop' of undefined
      at Context.<anonymous> (server/api/auth/auth.spec.js:18:45)

  2) Auth API "after all" hook:
     TypeError: Cannot read property 'drop' of undefined
      at Context.<anonymous> (server/api/auth/auth.spec.js:24:45)

My code was working before, and now it isn't. How can I create the collection?

---

Update: I ran db.collection.users.insert({ foo: 'bar' }) in the command line, and now it looks like the collection and document exist:

But I'm still having the same problem.

---

Update 2: This worked:

before(function(done) {
  // mongoose.connection.collections['users'].drop(function(err) {
  //   mongoose.connection.collections['users'].insert(user, done);
  // });
  User.remove({}).exec(function() {
    User.create(user, done);
  });
});

Now when I run the old code, it also works:

 before(function(done) {
  mongoose.connection.collections['users'].drop(function(err) {
    mongoose.connection.collections['users'].insert(user, done);
  });
//   User.remove({}).exec(function() {
//     User.create(user, done);
//   });
});

There's something weird going on here...

Answer 1

The reason why it was all failing before is because the "mongoose methods" employ their own "magic" that awaits the connection to be present before actually doing anything. The node native driver methods accesssed through the .collection accessor you are using have no such protection.

Thus "until" an actual "mongoose method" has already "fired" within your scripted logic, then there is no connection and such calls will simply return undefined . This is why it worked for you after you acutally called one of those methods first.

The fix for this if you want to use the native driver methods is quite simple. Being that you are either "sure" that one of the "mongoose methods" is going to fire "first", Or you just wrap your whole script logic ( after requiring mongoose and defining the connection ) with this:

mongoose.connection.on("connect", function(err) {
   // all tests and setup in here
});

This makes "sure" that the database connection has always been made before any other code that works with the database is done.

Whilst mongoose makes efforts to "hide this away", it is good practice to implement this in both your tests and any application startup code, so you can then "ensure" that the connection is actually established before trying to work with the database connection in any other way.

Answer 2

mongoose.connection.collections['users'] is returning undefined , and then you're trying to call drop() on it. So you are dropping a collection that doesn't exist, because you've already dropped it - last time the after ran.

Try checking that it exists before you attempt to use it, for example:

var users = mongoose.connection.collections['users'];
if (users) {
    users.drop(...callback...);
}

Also, when you run db.collection.users.insert({ foo: 'bar' }) in the terminal, if the collection doesn't exist, it gets created automatically.