I have set of active record object in array.
I just want to delete on object from array not in database
a = Model.limit(2)
b = Model.first
a.delete(b)
returning nil value
Its not deleting
is there anyway?
Add a comment
|
3 Answers
a.to_a - [b]
Background: a.to_a convertrs the relation into an array in in memory.
[b] is an array whith just the element, you want to delete (in memory).
a.to_a - [b] does an array substraction.
(In Rails 3.2 .to_a was applied automatically to a relation when it was accessed. I agree with gregates: It's better to convert the relation to an array explicitly)
Comments
There's potentially some confusion here because in ActiveRecord, Model.limit(2) does not return an array.
Model.limit(2).class #=> ActiveRecordRelation
So when you call a.delete(b), you may not be calling Array#delete.
Try this instead:
a = Model.limit(2).to_a # Executes the query and returns an array
b = Model.first
a.delete(b)
2 Comments
semiomant
nice idea to use
all to get an array out of the relation. I tried and to_a works as well and might be a fraction more explicit.
David Morales
all does not return an array anymore in Rails 4.2, to_a does.This is what you need:
objects_in_db = Model.all
objects_in_array = Model.first(2)
objects_in_array.delete_if { |obj| !objects_in_db.include?(obj)}
In your case, Model.limit(2) may not return the first two object and so the array a may not contain b and hence, it returns nil.
2 Comments
sangeethkumar
i can see the matching object is avail in b
itz2k13
can you provide your model's structure?. Try with some other model and see if there is any problem with your model.
