A Deep Dive into Mutations with Absinthe

Absinthe for Elixir is a powerful tool for building GraphQL APIs, and in this article, Sapan Diwakar takes a deep dive into mutations with Absinthe. Mutations in GraphQL are used to modify data on the server, and Absinthe makes it easy to implement them in Elixir.

The article starts by explaining the difference between queries and mutations in GraphQL. While queries are used to fetch data, mutations are used to modify data. The author provides an example of a mutation to create a new post and explains the structure of a typical mutation in GraphQL.

Next, the article shows how to implement mutations with Absinthe. It starts by creating an input object that can be used as a variable for the mutation. The author demonstrates how to define an input object using the input_object macro and explains the differences in field definitions between input objects and output types.

After defining the input object, the article moves on to defining the mutation type in the schema. The author uses the mutation..do..end block to define the base mutation type and creates a field named create_post that takes an argument of the post_create_input type defined earlier.

To actually perform the mutation operation, the article explains how to define a resolver. The author provides an example of a resolver that creates a post using the post attribute.

Overall, this article provides a comprehensive guide to implementing mutations with Absinthe for Elixir. It covers the basics of mutations in GraphQL, demonstrates how to define input objects and mutation types in Absinthe, and shows how to write resolvers to handle mutations. For developers looking to build GraphQL APIs with Elixir, this article is a valuable resource.

# Example code snippet from the article

# Define an input object
input_object :post_create_input do
  field :title, non_null(:string)
  field :content, non_null(:string)
  field :state, :post_state_enum, default_value: :draft
end

# Define the mutation type
mutation do
  field :create_post, :post_mutation_result do
    arg :post, :post_create_input
    resolve &Resolvers.create_post/3
  end
end

# Resolver to create a post
def create_post(_, %{post: post}, _) do
  # Logic to create a post
end

For more information on implementing mutations with Absinthe, be sure to check out the full article.