Field/key named "id", different than "_id"?

[Dean Langford]

From what I gather (after reading the documentation, some experimentation and some googling) keys with a name of "id" are not really allowed when using MongoMapper? And that :id is basically a synonym for the "_id" primary key field in a MongoDB collection? Is this correct?

My problem is that I have an existing MongoDB database in which one collection has a non-primary key field name "id", in addition to it's "_id" field.

If my assumption here is correct, is there any way I can use MongoMapper with such a collection? Any workarounds of which I am not aware?

Thanks

[Brian Hempel]

You are going to have quite a bit of trouble.

For getting/setting you can skip the id method and get/set the key directly...

my_object[:id]

my_object[:_id]

my_object[:id]  = ObjectId.new()

my_object[:_id] = ObjectId.new()

...but for querying, all your queries on :id will be turned into queries on :_id, so you're out of luck there unless you drop to the driver...

MyClass.collection.find( {:id => "something"}, :transformer => lambda { |doc| MyClass.load(doc) } )

Brian

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[Jamie Orchard-Hays]

Mongodb stores ids in a special field called "_id". All entries in a collection will have these.

MongoMapper maps _id to id; therein lies your problem. I'd drop into the driver or mongo shell and rename your "id" fields to something else.

Jamie

[Sam Bennett]

You are correct about this however, looking into the source code for the gem I found that the if statement for checking that you have used id, if removed fixes the issue. I have created a forked change that allows you to use this. I am just looking at a way to make it flagable.

[Chris Heald]

You'll also need to fix the mappings via Normalizers::HashKey in Plucky, as keys are translated there as well.