Fix create_resource authorization breaking with has_one association

[valscion]

We seem to have missed a test case for the related_records_with_context cases and so have got this bug. Credits to @nbarthel for discovering this case in #65, thanks!

Closes #65

[valscion]

Do these changes look good to you, @gnfisher? After all, you were the one these relationship checks in #60 so I value your input on this.

Do you think the data[:records] would need a rename in the related_records_with_context as it can contain just a single record, too? I don't yet have a good idea on what to call it, if we deem records can be a bit deceiving. Do you have any ideas?

[gnfisher]

The changes look good. I'm trying to remember back to this and how the has_one scenario wasn't an issue that came up in my use/testing (we're using a version of this in our project at work and haven't run up against this scenario - thankfully ;)).

As for naming the variable, this morning nothing strikes me as any better than records off hand. Ideally I'd like for data[:records] to always be an Array, which I'm sure is what I thought I was doing at the time. This way, even if it's a singular has_one relationship, it is still an array, just one with a single item.

[valscion]

Ideally I'd like for data[:records] to always be an Array, which I'm sure is what I thought I was doing at the time. This way, even if it's a singular has_one relationship, it is still an array, just one with a single item.

Yeah I thought about this as well, but then it would make some quite funky code in authorize_related_resources when replace_to_one_relationship is called. We'd have to unwrap the array and only take the first item from there, in order to not to change the API of replace_to_one_relationship to also accept an array of records. 😕

[valscion]

Oh, and if the changes look good to you, could you approve the review? The big red "Review required" text doesn't really encourage me to bypass it 😄