Select has incorrect return type when passed a block about sorbet-rails HOT 6 CLOSED

Hi Riley, like you said, sorbet doesn't support having 2 sig for one method. The .select method that returns an array is a select performed on the materialized element of an active record.

You can convert the relation to array then perform select for typechecking.
For example: User.all.to_a.select <- This will take a block and returns an Array

Let me know if this is helpful.

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Do you want to remove the block as a parameter then? Right now, the sig produced implies that you can pass in a block and return an ActiveRecord_Relation, which will not happen. It also implies you can pass both args and a block, which will throw a runtime error.

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Making the return type of select be T.any(User::ActiveRecord_Relation, T::Array[User]) is not great, because callers will always have to check which type is being returned, even though it can always be inferred from the argument type.

Yeah, this is a limitation of Sorbet. Unless they start supporting sig overloading (mutltiple sigs per def ), this is impossible to express using the type system.

I agree that returning T.any(User::ActiveRecord_Relation, T::Array[User]) is a worse user experience.

My workaround is adding to_a before any enumerable selects, i.e. replacing this:

User.where(foo: 'bar').select(&:some_predicate)

...with this:

User.where(foo: 'bar').to_a.select(&:some_predicate)

🤷‍♂

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If the block argument doesn't get removed, there's another issue there where args it yields are treated by sorbet as NilClass. This is the sig that currently gets generated in the User::ActiveRecord_Associations_CollectionProxy

  sig { params(args: T.untyped, block: T.nilable(T.proc.void)).returns(User::ActiveRecord_Relation) }
  def select(*args, &block); end

  foo.users.select {|u| T.reveal_type(u)} # Revealed type: NilClass

If the generated sig looked like this:

  sig { params(args: T.untyped, block: T.proc.params(user: User).void).returns(User::ActiveRecord_Relation) }
  def select(*args, &block); end

  foo.users.select {|u| T.reveal_type(u)} # Revealed type: User

It would be handy. At the moment you have to either call to_a as @pje said. This is separate from the issue of the return type, which I don't have a strong opinion on yet.

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