Document Adapters

Absinthe supports an adapter mechanism that allows developers to define their schema using one code convention (eg, snake_cased fields and arguments), but accept query documents and return results (including names in errors) in another (eg, camelCase). This is useful in allowing both client and server to use conventions most natural to them.

Absinthe ships with two adapters:

  • Absinthe.Adapter.LanguageConventions, which expects schemas to be defined in snake_case (the standard Elixir convention), translating to/from camelCase for incoming query documents and outgoing results. This is the default as of v0.3, and it is highly recommended that it's the adapter you use, as introspection currently makes certain assumptions about how to return results.
  • Absinthe.Adapter.Underscore, which is similar to the LanguageConventions adapter but converts all incoming identifiers to underscores and does not modify outgoing identifiers (since those are already expected to be underscores). Unlike Absinthe.Adapter.Passthrough this does not break introspection.
  • Absinthe.Adapter.Passthrough, which is a no-op adapter and makes no modifications.

To set the adapter, you provide it as an option to, MyAppWeb.Schema,
             adapter: Absinthe.Adapter.TheAdapterName)

Notably, this means you're able to switch adapters on case-by-case basis. In a Phoenix application, this means you could even support using different adapters for different clients.

A custom adapter module must merely implement the Absinthe.Adapter behaviour, in many cases with use Absinthe.Adapter and only overriding the desired functions.

Note that types that are defined external to your application (including the introspection types) may not be compatible if you're using a different adapter.