Absinthe Constraints

An absinthe library to add type constraints to your GraphQL schema using directives.

Installation

Install from Hex.pm

def deps do
  [
    {:absinthe_constraints, "~> 0.2.0"}
  ]
end

Usage

1. Add the constraints directive's prototype schema to your schema

defmodule MyAppWeb.Schema do
  use Absinthe.Schema

  @prototype_schema AbsintheConstraints.Directive

  # Use `import_sdl`, etc...
end

2. Add the document phase to your absinthe Pipeline

Example using Absinthe.Plug:

# Somewhere in your router

def my_pipeline(config, opts) do
  config
  |> Absinthe.Plug.default_pipeline(opts)
  |> AbsintheConstraints.Phase.add_to_pipeline(opts)
end

forward("/", Absinthe.Plug, schema: MyAppWeb.Schema, pipeline: {__MODULE__, :my_pipeline})

3. Add constraints to your schema

# Somewhere in your schema

# Adding constraints to input object's fields
input_object :coordinates do
  field(:latitude, non_null(:float), directives: [constraints: [min: -90, max: 90]])
  field(:longitude, non_null(:float), directives: [constraints: [min: -180, max: 180]])
end

# Adding constraints to query field's arguments
object :my_queries do
  field :my_field, non_null(:string) do
    arg(:id, non_null(:string), directives: [constraints: [format: "uuid"]])
    resolve(&my_resolver/2)
  end
end

Supported constraints

String

min_length

directives: [constraints: [min_length: 5]] Restrict to a minimum length

max_length

directives: [constraints: [max_length: 5]] Restrict to a maximum length

format

directives: [constraints: [format: "uuid"]] Ensure value is in a particular format

Supported formats:

• "uuid" - uses :elixir_uuid to validate the value
• "email" - uses a regex to validate the value

pattern

directives: [constraints: [pattern: "^[A-Z][0-9a-z]*$"]] Ensure value follows a specific Regex pattern

Number (integer/float)

min

directives: [constraints: [min: 5]] Ensure value is greater than or equal to

max

directives: [constraints: [max: 5]] Ensure value is less than or equal to

List

min_items

directives: [constraints: [min_items: 5]] Restrict to a minimum number of items

max_items

directives: [constraints: [max_items: 5]] Restrict to a maximum number of items