Dataloader error

Questions / Help
,
1

Unable to find item [“4039624a-9b02-448d-8158-0db13da76efb”] in batch
why this error can produced? it happened when we use big graph query with connections?

2

Hi @MeterSoft as I mentioned in the issue you opened, this is happening because you are calling Dataloader.get with a value that you did not call Dataloader.load with. As with any error, please show example code that causes it.

3

@benwilson512 i think problem related when i use connection and dataloder. when i replace connection.from_query with custom pagination the problem gone. I can not provide original code because it is a lot…

but a short example

connection field(:announcements, node_type: :announcement) do
  resolve allow_deleted_user_2 &AnnouncementResolver.all/2
end

defmodule AnnouncementResolver do 
  def all(args, %{context: %{current_user: user}}) do
    Connection.from_query(Announcement.all_for_user(user, args), &Repo.all/1, args)
  end
end

... on AnnouncementList {
  announcements(first: 5) {
    __typename
    ...announcementConnectionFragment
  }
}

and it works for

connection field(:announcements, node_type: :announcement) do
   resolve dataloader_many_paginated(DB, Announcement, :announcements_list)
 end

def dataloader_many_paginated(source, queryable, type, alt_filter \\ nil) do
    fn parent, args, %{context: %{loader: loader}} = _resolution ->
      second_filter = if alt_filter != nil && args[:with_fallback] != true, do: %{}, else: alt_filter
      args = args_with_pagination!(args, second_filter) # for lateral-join connection (paginated)
      loader
      |> Dataloader.load(source, {:many, queryable, args}, [{type, parent.id}])
      |> on_load(fn loader ->
        loader
        |> Dataloader.get(source, {:many, queryable, args}, [{type, parent.id}])
        |> from_paginated_records(args, [])
        |> add_parent_id(parent.id)
      end)
    end
  end