Specify _id with uuid

[porsager]

Hi.

We want to use client generated id's in the form of UUID's in our setup, and would like to know if this is supported by Mongoose, or if there is an implementation to make it work??

It should be possible with Mongo to do this as per: http://www.mongodb.org/display/DOCS/Object+IDs#ObjectIDs-UUIDs

It seems the problem is with casting the _id when creating a new document, so maybe a plugin to mongoose to override this function could be made?

[aheckmann]

in your schema, declare your _id to be either String or Buffer, then add a function default to generate it for you:

new Schema({ _id: { type: String, default: function genUUID () { .. }}})

[aheckmann]

the fn should return the value you want to use.

[porsager]

Ah, right in front of me.

Sorry, i should have been able to figure this out myself. Thank you very much!

[aheckmann]

Anytime :)

On Jul 25, 2012, at 8:31 AM, porsagerreply@reply.github.com wrote:

Ah, right in front of me.

Sorry, i should have been able to figure this out myself. Thank you very much!

---

Reply to this email directly or view it on GitHub:
#1026 (comment)

[jaufgang]

in http://docs.mongodb.org/manual/core/document/#the-id-field it says:

For a more efficient storage of the UUID values in the collection and in the _id index, store the UUID as a value of the BSON BinData type.

The Mongo shell has a UUID() method that will convert a UUID string and convert it to BinData format (http://docs.mongodb.org/manual/reference/method/UUID/), but how do I do this through the Mongoose API? Is it possible to read/write the UUID from/to the model as a string but have Mongoose map to the BinData format in the DB? Or is there a convenience method for doing the conversion?

Thanks for any help

[vkarpov15]

I'm not terribly familiar with UUID's - maybe the Binary type in the node driver will help? See docs

[rsp]

@jaufgang the UUID() function in Mongo is a little bit strange. It doesn't work for valid UUIDs:

> UUID('343881b7-852c-46cf-b74c-4a0bca2fae9c')
E QUERY    Error: UUID string must have 32 characters

while according to Wikipedia:

In its canonical textual representation, the sixteen octets of a UUID are represented as 32 lowercase hexadecimal (base 16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters

See: https://en.wikipedia.org/wiki/Universally_unique_identifier#Format

It only works when you manually remove the dashes:

> UUID('343881b7852c46cfb74c4a0bca2fae9c')
BinData(3,"NDiBt4UsRs+3TEoLyi+unA==")

@porsager For using UUIDs with Mongoose, there are two modules that you can use:

• https://www.npmjs.com/package/mongoose-uuid
• https://www.npmjs.com/package/mongoose-uuid2

See also those issues:

• Using UUIDs instead of ObjectIDs #2738
• Make UUID a formal Schema.Type #3208

and this article for some potential problems with binary UUID representations in Mongo:

• http://3t.io/blog/best-practices-uuid-mongodb/