Gain insights into crafting GraphQL APIs with Elixir's Absinthe. Explore building schemata, securing endpoints, and integrating frontends to master creating, publishing, and utilizing robust GraphQL APIs.

Craft GraphQL APIs in Elixir with Absinthe.png

graphql.tar.gz

Chapter_2_1_start

Chapter_2_2_object_Running_GraphQLServer

Chapter_2_2_object

Chapter_3_3_matching

Chapter_3_3_matching_GraphQiL

Chapter_4_2_Union_GraphQiL

Chapter_5_2_Create

Chapter_6_4-publish

Chapter_6_4-orderingapi

Chapter_7_5-default

Chapter_8_2-login

Chapter_8_3-context

Chapter_9_dataloader

Chapter_10_Start

Chapter_10_2_action

Chapter_10_3_put

Chapter_10_4_login

Chapter_10_5_History

Chapter_11_2_subsription

Chapter_11_1_start

Chapter_11_hybird

Chapter_11_Applo_Client

Chapter_11_1_start-Updated

Chapter11-2-HTTP-Subscription

Chapter11-2-HTTP-Relay-Subscription

GraphQL is an API query language that allows clients to ask for exactly what they need and nothing more makes it easier to evolve APIs over time.

This course is divided into three parts, Part 1- Build a GraphQL API, Part 2- Publish Your API, and Part-3 Use Your API. 

In the first part, you will cover topics ranging from basic GraphQL, Building GraphQL Schema, Taking User Input, Adding Flexibility, Making a Change with Mutations, and Going Live with Subscriptions.

In the second part, you will cover topics ranging from Resolution Middleware, Securing with Authentication and Authorization, and Tuning Resolution.

The third part will cover topics ranging from Driving Phoenix Actions with GraphQL, Integrating with the Frontend and GraphQL Types. Upon completing this course, you will have sufficient foundational knowledge of GraphQL, and you can build, publish and use your API in GraphQL.

Craft GraphQL APIs in Elixir with Absinthe

# Building the resolver
Let’s build the resolver function. It will grab the `:input` argument for us, and then call a general-purpose `PlateSlate.Menu.create_item/1` unction that will handle  persisting the record:

def create_item(_, %{input: params}, _) do 
  case Menu.create_item(params) do
    {:error, _} ->
      {:error, "Could not create menu item"}
    {:ok, _} = success ->
      success
   end
end


Here’s how we’ve implemented `PlateSlate.Menu.create_item/1`:



def create_item(attrs \\ %{}) do 
  %Item{}
  |> Item.changeset(attrs)
  |> Repo.insert()
end

The actual persistence of the menu items is straightforward, but requires us to know a little about how Ecto works. The important thing to know here is that an Ecto changeset models the data that needs to be inserted or updated in a database. Here, our `create_item/1` function takes the menu item attributes, creates an Ecto changeset using `PlateSlate.Menu.Item.changeset/1`, and attempts to insert it into the `PlateSlate.Repo`. It is aliased for convenience here as "Repo." If you look back at **_line 2_** of the resolver, you’ll notice that we use case to handle the result of the `create_item` function. While the return value of a successful `Repo.insert/2` is compatible with a resolution result, the `{:error, changeset}` that it may return isn’t. For the moment, when an error occurs, we just return an error message from the field resolver. However, we’ll look at some options for error reporting at the end of this course.

Let’s talk a bit about what happens when persistence is successful.


# Returning data from mutations

Remember, when we defined the mutation field, we declared the  type of object it would have as a result by passing `:menu_item` as the second argument to the field macro:

Learn how to create a resolver function and how to return data from mutations.


Resolver Function

Learn how to create a resolver function and how to return data from mutations.

Getting Started

Meet GraphQL

Building Schema of GraphQL

Taking User Input

Adding Flexibility

Making a Change with Mutations

Going Live with Subscriptions

Resolution Middleware

Securing with Authentication and Authorization

Tuning Resolution

Driving Phoenix Actions with GraphQL

Integrating with the Front-end

Conclusion

Resolver Function

Building the resolver