Graphql-ruby: Duplicate type definition found for name

[volkanunsal]

I define fields on a type dynamically from an ActiveRecord attribute. I wrote a helper method for that and it basically loops over the attributes and calls field(name, type) inside the define block.

MyType = GraphQL::ObjectType.define do 
   Company.graphql_types do |name, type|
      field name, type
   end
end

The problem here is that anytime I change the file that defines these types, GraphQL complains. Apparently, the GraphQL::Schema::Traversal.visit method is doing an object identity check and it rejects types defined by a reloaded type file. I'm not sure what the best way forward would be to avoid this error. Do you have any suggestions?

[rmosolgo]

Sorry, this is a bad side-effect of the current DSL 😖 It doesn't play nice with Rails autoloading, since it re-loads the files but code still retains references to old objects.

One thing that might work is to use Procs instead of bare references to the type objects, eg:

# Instead of 
{ company: CompanyType } 
# Try: 
{ company: -> { CompanyType } }

This way, the Proc will be re-evaluated each time and it might find the _new_ version of the type.

Now that I'm reading again, I'm not sure I've understood the problem correctly. Maybe you could use reload_dependency to reload the schema when one of those files changes?

[volkanunsal]

I tried wrapping the types in procs, but it didn't solve my problem. The error is coming from this code block:

elsif !prev_type.equal?(type_defn)
  # If the previous entry in the map isn't the same object we just found, raise.
  raise("Duplicate type definition found for name '#{type_defn.name}'")
end

Link

I think reloading the type definitions is creating a new object, and that seems to be unacceptable to visit method. To be honest, I don't understand why the code needs to check for the object identity here. I'm sure there is a reason, but when I comment out that exception, it still works fine. If it's absolutely necessary to check the object identity, can we at least throw a named exception that can be caught from the schema controller in development mode, so we don't need to monkey patch this code block?

[volkanunsal]

Reading your post again, I might reload schema, too, but where is reload dependency defined? Is that a Rails method?

[rmosolgo]

Yep, Rails: http://guides.rubyonrails.org/autoloading_and_reloading_constants.html#require-dependency

[volkanunsal]

That solved it. Thank you!

[daqo]

In case anyone else faced this problem, what you need to do is to create a new initializer file with the following content in it:

if Rails.env.development?
  lib_ruby_files = Dir.glob(File.join('app/**', '*.rb'))
  lib_reloader ||= ActiveSupport::FileUpdateChecker.new(lib_ruby_files) do
    lib_ruby_files.each do |lib_file|
      silence_warnings { require_dependency(lib_file) }
    end
  end

  ActionDispatch::Callbacks.to_prepare do
    lib_reloader.execute_if_updated
  end

end

[TSMMark]

@rmosolgo Hi I'm experiencing this when using a custom code reloading outside of Rails... Tried wrapping type references in lambdas to no avail.

Is there a graphql-ruby way to simply teardown my entire schema, member definitions, and everything else, and start over?

Been searching docs and source all day and can't find anything. Thank you!

[yanivskb]

@rmosolgo We've been seeing this error on our production logs recently. I don't quite understand what's triggering it. I understand that it's an object identity issue, but what are the circumstances under which we should expect to see reloaded objects, and why does graphql-ruby hold on to outdated code? Is it possible for graphql-ruby to re-attempt a traversal with fresh code?

[rmosolgo]

I think this happens when Rails apps boot on multiple threads. Different threads load constants at slightly different times, but they all exist in the same Ruby process, so they have a conflict in the GraphQL schema.

For GraphQL-Ruby 1.9 or below, see a work-around here: https://github.com/rmosolgo/graphql-ruby/issues/1505#issuecomment-538442074

For GraphQL-Ruby 1.10+, there's an improved schema loading system that can be opted into as described here: https://github.com/rmosolgo/graphql-ruby/issues/1505#issuecomment-585299090

[yanivskb]

@rmosolgo thanks for the quick response! And sorry for bothering you with a problem you've already addressed in another issue. Hopefully search engines will give that thread more prominence in the future.