Preventing duplicate records in Mongoose

Question

I'm fairly new to MongoDb / Mongoose, more used to SQL Server or Oracle.

I have a fairly simple Schema for an event.

EventSchema.add({
  pkey: { type: String, unique: true },
  device: { type: String, required: true },
  name: { type: String, required: true },
  owner: { type: String, required: true },
  description: { type: String, required: true },
});

I was looking at Mongoose Indexes which shows two ways of doing it, I used the field definition.

I also have a very simple API that accepts a POST and calls create on this collection to insert the record.

I wrote a test that checks that the insert of a record with the same pkey should not happen and that the unique:true is functioning. I already have a set of events that I read into an array so I just POST the first of these events again and see what happens, I expected that mongo DB would throw the E11000 duplicate key error, but this did not happen.

var url = 'api/events';
var evt = JSON.parse(JSON.stringify(events[0]));

// POST'ed new record won't have an _id yet 
delete evt._id;

api.post(url)
   .send(evt)
   .end(err, res) {
     err.should.exist; 
     err.code.should.equal(11000); 
   }); 

The test fails, there is no error and a duplicate record is inserted.

When I take a look at the collection I can see two records, both with the same pkey (the original record and the copy that I posted for the test). I do notice that the second record has the same creation date as the first but a later modified date.

(does mongo expect me to use the latest modified version record???, the URL is different and so is the ID)

[ { _id: 2,
    pkey: '6fea271282eb01467020ce70b5775319',
    name: 'Event name 01',
    owner: 'Test Owner',
    device: 'Device X',
    description: 'I have no idea what\'s happening',
    __v: 0,
    url: '/api/events/2',
    modified: '2016-03-23T07:31:18.529Z',
    created: '2016-03-23T07:31:18.470Z' },
  { _id: 1,
    pkey: '6fea271282eb01467020ce70b5775319',
    name: 'Event name 01',
    owner: 'Test Owner',
    device: 'Device X',
    description: 'I have no idea what\'s happening',
    __v: 0,
    url: '/api/events/1',
    modified: '2016-03-23T07:31:18.470Z',
    created: '2016-03-23T07:31:18.470Z' }
]

I had assumed that unique: true on the field definition told mongo db that this what you wanted and mongo enforced that for you at save, or maybe I just misunderstood something...

In SQL terms you create a key that can be used in URL lookup but you can build a unique compound index, to prevent duplicate inserts. I need to be able to define what fields in an event make the record unique because on a form data POST the submitter of a form does not have the next available _id value, but use the _id (done by "mongoose-auto-increment") so that the URL's use from other parts of the app are clean, like

/events/1

and not a complete mess of compound values, like

/events/Event%20name%2001%5fDevice%20X%5fTest%20Owner

I'm just about to start coding up the so for now I just wrote a simple test against this single string, but the real schema has a few more fields and will use a combination of them for uniqueness, I really want to get the initial test working before I start adding more tests, more fields and more code.

Is there something that I should be doing to ensure that the second record does not actually get inserted ?

Answer 1

It seems that you have done unique indexing(at schema level) after inserting some records in db.

please follow below steps to avoiding duplicates -

1) drop your db:

$ mongo

> use <db-name>;

> db.dropDatabase();

2) Now do indexing at schema level or db level

 var EventSchema = new mongoose.Schema({
      pkey: { type: String, unique: true },
      device: { type: String, required: true },
      name: { type: String, required: true },
      owner: { type: String, required: true },
      description: { type: String, required: true },
    });

It will avoid duplicate record insertion with same pKey value.

and for ensuring the index, use command db.db_name.getIndexes().

I hope it helps. thank you