It can be done via ActiveRecord#where, but you lose the semantics of using
#find. Under the hood, I suppose ActiveRecord just does a #where and then
compares the results, so you're not technically losing any optimization
that way either (at least for the current implementation of #find).
On the other hand, it basically forces you to reimplement the #find method
yourself if you want the additional information. I think there's a valid
use case here, but if status quo is the community preference, I'll
graciously concede the point.
On Tuesday, June 21, 2016 at 10:15:04 AM UTC-4, Saiqul Haq wrote:
>
> I think we can achieve this with ActiveRecord#where method, e.g.:
>
> 3.times { Book.create! } #=> which returned 3 records, id = 1, 2, 3
>
> then I want to find Book records with ID 1, 2, and 5
> so
> expected_records = [1,2,5]
> books = Book.where id: expected_records
>
> then to get to know which results were missing is by
>
> missing_records = expected_records - books.pluck(:id)
>
> Pada Selasa, 21 Juni 2016 11.34.23 UTC+7, Robert Smith menulis:
>>
>> When I perform an ActiveRecord::Base.find(...) operation with multiple
>> ids, and there is at least one result that is not found, ActiveRecord
>> raises a RecordNotFound error. The error message lists the requested ids
>> and the number of results requested and found. An example:
>>
>> class Book < ActiveRecord::Base; end
>>
>> 3.times { Book.create }
>> # Creates books with ids 0, 1, 2
>>
>> begin
>> Book.find(0, 1, 5)
>> rescue ActiveRecord::RecordNotFound => exception
>> puts exception.message
>> end
>> # "Couldn't find all Books with 'id': (0, 1, 5) (found 2 results, but was
>> looking for 3)"
>>
>> As a developer, I want to know which results were returned and which were
>> not. In our example, ActiveRecord::FinderMethods#find_some actually does
>> have the found results, which it checks against the expected size. However,
>> the result itself is discarded and only the result size is passed into the
>> error via the #raise_record_not_found_exception! method.
>>
>> My proposal is to add an additional, optional #result property to the
>> RecordNotFound error, which is set to the result of the query. This allows
>> downstream code to know which records were found (and deduce which records
>> were not found by comparing the found records with the expected ids). For
>> example, this could allow a controller to display a more helpful error
>> message to the end user, or allow a library to wrap the RecordNotFound with
>> additional logic around found/missing records.
>>
>> I've built a quick example branch, see
>> https://github.com/sleepingkingstudios/rails/commit/e11a70ef60bbb60e57a081c6e313580880b4570a
>> .
>>
>> Any feedback would be appreciated.
>>
>> Regards,
>>
>> Rob Smith
>>
>
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