Crudry

v2.4.0

Crudry v2.4.0 Crudry.Resolver View Source

Generates CRUD functions to DRY Absinthe Resolvers.

Requires a previously generated Context.

Usage

To generate CRUD functions for a given schema resolver, simply do

defmodule MyApp.MyResolver do
  alias MyApp.Repo
  alias MyApp.MyContext
  alias MyApp.MySchema
  require Crudry.Resolver

  Crudry.Resolver.generate_functions MyContext, MySchema
end

And the resolver will have all these functions available:

defmodule MyApp.MyResolver do
  alias MyApp.Repo
  alias MyApp.MyContext
  alias MyApp.MySchema
  require Crudry.Resolver

  def get_my_schema(%{id: id}, _info) do
    id
    |> MyContext.get_my_schema()
    |> nil_to_error("my_schema", fn record -> {:ok, record} end)
  end

  def list_my_schemas(_args, _info) do
    {:ok, MyContext.list_my_schemas([])}
  end

  def create_my_schema(%{params: params}, _info) do
    MyContext.create_my_schema(params)
  end

  def update_my_schema(%{id: id, params: params}, _info) do
    id
    |> MyContext.get_my_schema()
    |> nil_to_error("my_schema", fn record -> MyContext.update_my_schema(record, params) end)
  end

  def delete_my_schema(%{id: id}, _info) do
    id
    |> MyContext.get_my_schema()
    |> nil_to_error("my_schema", fn record -> MyContext.delete_my_schema(record) end)
  end

  # If `result` is `nil`, return an error. Otherwise, apply `func` to the `result`.
  def nil_to_error(result, name, func) do
    case result do
      nil -> {:error, %{message: "not found", schema: name}}
      %{} = record -> func.(record)
    end
  end

  def add_info_to_custom_query(custom_query, info) do
    fn initial_query -> custom_query.(initial_query, info) end
  end
end

Link to this section Summary

Functions

default(opts)

Sets default options for the resolver.

generate_functions(context, schema_module, opts \\ [])

Generates CRUD functions for the schema_module resolver.

Link to this section Functions

Link to this macro

default(opts)

View Source (macro)

Sets default options for the resolver.

Options

  • :only - list of functions to be generated. If not empty, functions not specified in this list are not generated. Defaults to [].

  • :except - list of functions to not be generated. If not empty, only functions not specified in this list will be generated. Defaults to [].

  • list_opts - options for the list function. See available options in Crudry.Query.list/2. Defaults to [].

  • create_resolver - custom create resolver function with arity 4. Receives the following arguments: [Context, schema_name, args, info]. Defaults to nil.

  • not_found_message - custom message for the nil_to_error function. Defaults to "not found".

  • primary_key - custom primary key argument to use in get, update and delete resolvers. Defaults to :id.

Note: in list_opts, custom_query will receive absinthe's info as the second argument and, therefore, must have arity 2. See example in generate_functions/3.

The accepted values for :only and :except are: [:get, :list, :create, :update, :delete].

Examples 

iex> Crudry.Resolver.default only: [:create, :list]
:ok

iex> Crudry.Resolver.default except: [:get!, :list, :delete]
:ok

iex> Crudry.Resolver.default list_opts: [order_by: :id]
:ok

iex> Crudry.Resolver.default list_opts: [custom_query: &scope_list/2]
:ok
Link to this macro

generate_functions(context, schema_module, opts \\ [])

View Source (macro)

Generates CRUD functions for the schema_module resolver.

Custom options can be given. To see the available options, refer to the documenation of Crudry.Resolver.default/1, noting that the not_found_message must only be configured using default/1.

Examples

Overriding functions

To define a custom function, add it to except and define your own. In the following example, the schema is updated with its association.

defmodule MyApp.Resolver do
  alias MyApp.Repo
  alias MyApp.MyContext
  alias MyApp.MySchema
  require Crudry.Resolver

  Crudry.Resolver.generate_functions MyContext, MySchema, except: [:update]

  def update_my_schema(%{id: id, params: params}, _info) do
    id
    |> MyContext.get_my_schema()
    |> nil_to_error("My Schema", fn record -> MyContext.update_my_schema_with_assocs(record, params, [:assoc]) end)
  end
end

By using the nil_to_error function, we DRY the nil checking and also ensure the error message is the same as the other auto-generated functions.

Custom create resolver

It's possible to define a custom create function, useful when all functions in a resolver change the data in the same way before creating:

defmodule MyApp.Resolver do
  alias MyApp.Repo
  alias MyApp.MyContext
  alias MyApp.MySchema
  require Crudry.Resolver

  Crudry.Resolver.default create_resolver: &create_resolver/4)
  Crudry.Resolver.generate_functions MyContext, MySchema
  Crudry.Resolver.generate_functions MyContext, OtherSchema

  def create_resolver(context, schema_name, args, %{context: %{current_user: %{company_id: company_id}}}) do
    apply(context, :"create_#{schema_name}", [Map.put(args.params, :company_id, company_id)])
  end
end

Now when creating MySchema and OtherSchema, the custom function will put the current user's company_id in the params.

Custom query

It's also possible to use a custom query that has access to absinthe's info:

defmodule MyApp.Resolver do
  alias MyApp.Repo
  alias MyApp.MyContext
  alias MyApp.MySchema
  require Crudry.Resolver

  def scope_list(MySchema, %{context: %{current_user: current_user}} = _info) do
    where(MySchema, [p], p.user_id == ^current_user.id)
  end

  Crudry.Resolver.generate_functions MyContext, MySchema, list_opts: [custom_query: &scope_list/2]
end

With this, the list function will effectively become:

def list_my_schemas(_args, info) do
  {:ok, MyContext.list_my_schemas(custom_query: add_info_to_custom_query(scope_list, info))}
end

See Crudry.Query.list/2 for further information on the custom_query option.