增加mongo db中的索引

Question

When adding a field called date in mongo db, I can do just:

date: {
    type: Date,
    default: Date.now
}

and it will automatically add date field to my new collection when it was created. Is there some way to add a self-incrementing index ( id ) to my collections?

Note : I tried to do it on client side, however with every time I push collection with ( id ) field, its being deleted from the collection and replaced with _id which is a long string with random characters. Way to long!

Looking for every hints.

Edit: code responsible for adding use to db

app.post("/users", function (req, res) {
    createUser(req.body, function (err, user) {
        if (err) {
            return res.json(err);
        }
        return res.json(user);
    });
});

Answer 1

MongoDB automatically makes unique ids for each object in the database, resulting in each entry having a unique _id field being an ObjectId . You don't really need to worry about specifying custom ids.

You can sort by _id if you want objects roughly in the order they were created, or you could add a date field which is set on creation and sort by that.

Other than that, I'm not sure what you'd gain by having auto incrementing ids

Answer 2

There are multiple ways to implement an auto-increment index but it is not considered a good practice.

Detailed information here: Auto increment in MongoDB to store sequence of Unique User ID

Check Rizwan Siddiquee answer about how to implement it with a stored javascript function.

Another way would be to implement it on application layer using any kind of ODM but this is obviously dangerous and not so trustable for serious applications.