Craft GraphQL APIs in Elixir with Absinthe

Defining a Root Mutation Type

To support mutation operations, we need to define a root mutation type, just as we did for queries. This will be used as the entry point for GraphQL mutation operations, and it will define—based on the mutation fields that we add—the complete list of capabilities users of our API will have available to modify data.

We define the root mutation type by using the mutation macro in our schema:

05-chp.mutations/1-start/lib/plate_slate_web/schema.ex

mutation do
  # Mutation fields will go here
end

This might strike you as somewhat similar to our use of the query macro when we did the initial build-out of the PlateSlate Absinthe schema, and that’s by design. Both macros—query and mutation—are used to define the ...