Node.js mongodb无效的_id值

Question

Some company code has been creating documents with _id values that are not valid bson ObjectId values.

The code that has done so looks like:

var collection = getTheCollection();
collection.save(
    { _id: 'questionableId', /* more values */ },
    { w: 1, fsync: true },
    function(err, result) { /* ... */ }
)

Of course, if { _id: new ObjectID('questionableId'), /* ... */ } , was used the following error would be encountered:

Error: Argument passed in must be a single String of 12 bytes or a string of 24 hex characters
at new ObjectID (/.../mongodb-core/node_modules/bson/lib/bson/objectid.js:50:11)

Fortunately, everything seems to be working fine, with plenty of values like 'questionableId' in _id properties.

Is this code acceptable? Intuitively, I'd like to introduce a new id property for every document which can happily store values like 'questionableId' , and allow mongo to natively handle generating an _id property.

Is my company's current code risky?

Answer 1

You don't need to worry about the current implementation. It's a valid choice not to use an ObjectId for the _id field and there may have been reasons why things were done this way (try to find out about the background before you consider changing things).

The MongoDB documentation states:

MongoDB reserves the _id field in the top level of all documents as a primary key. _id must be unique, and always has an index with a unique constraint. However, except for the unique constraint you can use any value for the _id field in your collections.

Mind you, there are certain implicit features that you may or may not want to benefit from by switching to an ObjectId . You can, for instance, extract the creation data of any document from its ObjectId as described here .

Also, ObjectId is arguably by far the most used data type for the _id field and I would personally recommend using it, too.