Lists to Maps

Questions & Help Questions
11

Essentially you had an error in your schema:

web/schema.ex

query do
  @desc "Get all blog posts"
  field :posts, list_of(:post) do      # This needs list_of()
     resolve &Blog.PostResolver.all/2  # because this will return 0-to-many results
  end

  @desc "Get a user of the blog"
  field :user, type: :user do          # This doesn't need list_of()
    arg :id, non_null(:id)
    resolve &Blog.PostResolver.find/2  # because this will return 0-or-1 results
  end
end

The missing list_of resulted in the default_resolve being presented with data that it shouldn’t have to handle.
This demonstrates that one should not immediately assume that the fault lies where it manifests itself - the problem is often further up stream.