ConvertNulltoNotFoundError when calling DataAccessObject.findOne via rest

[albertoleal]

When we call the url http://localhost:3000/api/cars/1 with an invalid id we get a 404 error:

{
error: {
name: "Error",
status: 404,
message: "Unknown "cars" id "1".",
statusCode: 404,
stack: "Error: Unknown "cars" id 1". at Function...
} 
} 

But, when we try to use filters, such as http://localhost:3000/api/cars/findOne?filter%5Bwhere%5D%5Bid%5D=1, we have another behavior:

null

This PR follows the same approach found in: https://github.com/strongloop/loopback-datasource-juggler/blob/master/lib/dao.js#L364-L371

[slnode]

Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

[albertoleal]

Hi, do you any feedback about this pr?

[raymondfeng]

Thanks for the patch.

I'm not fully convinced whether reporting 404 is a good idea for findOne when no records are found. Maybe we should have a discussion on the group.

[albertoleal]

I understand that we should discuss about it on the group, but that's the same behavior we have for findById.

[ricobl]

I agree with @albertoleal, the message we're passing when we return a success response in this case is that the object exists and it is null.

A client should be able to consume both a findById URL and a findOne URL seamlessly with the same implementation.

Right now it has to deal with a success, a null success and errors.