Leverage Open Api Specification 3 (swagger) to document, test, validate and explore your Plug and Phoenix APIs.
- Generate and serve a JSON Open Api Spec document from your code
- Use the spec to cast request params to well defined schema structs
- Validate params against schemas, eliminate bad requests before they hit your controllers
- Validate responses against schemas in tests, ensuring your docs are accurate and reliable
- Explore the API interactively with with [SwaggerUI](https://swagger.io/swagger-ui/)
Full documentation available on [hexdocs](https://hexdocs.pm/open_api_spex/)
## Installation
The package can be installed by adding `open_api_spex` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:open_api_spex, "~> 3.4"}
]
end
```
## Generate Spec
Start by adding an `ApiSpec` module to your application to populate an `OpenApiSpex.OpenApi` struct.
```elixir
defmodule MyAppWeb.ApiSpec do
alias OpenApiSpex.{OpenApi, Server, Info, Paths}
alias MyAppWeb.{Endpoint, Router}
@behaviour OpenApi
@impl OpenApi
def spec do
%OpenApi{
servers: [
# Populate the Server info from a phoenix endpoint
Server.from_endpoint(Endpoint)
],
info: %Info{
title: "My App",
version: "1.0"
},
# populate the paths from a phoenix router
paths: Paths.from_router(Router)
}
|> OpenApiSpex.resolve_schema_modules() # discover request/response schemas from path specs
end
end
```
For each plug (controller) that will handle api requests, add an `open_api_operation` callback.
It will be passed the plug opts that were declared in the router, this will be the action for a phoenix controller. The callback populates an `OpenApiSpex.Operation` struct describing the plug/action.
+[example web app](https://github.com/open-api-spex/open_api_spex/blob/master/examples/phoenix_app/lib/phoenix_app_web/controllers/user_controller.ex).
-Declare the JSON schemas for request/response bodies in a `Schemas` module:
+Next, declare the JSON schemas for request/response bodies in a `Schemas` module:
Each module should implement the `OpenApiSpex.Schema` behaviour.
The only callback is `schema/0`, which should return an `OpenApiSpex.Schema` struct.
You may optionally declare a struct, linked to the JSON schema through the `x-struct` extension property.
See `OpenApiSpex.schema/1` macro for a convenient way to reduce some boilerplate.
For more examples of schema definitions, see the [sample Phoenix app](https://github.com/open-api-spex/open_api_spex/blob/master/examples/phoenix_app/lib/phoenix_app_web/schemas.ex)
Now you can create a mix task to write the swagger file to disk:
```elixir
defmodule Mix.Tasks.MyApp.OpenApiSpec do
def run([output_file]) do
json =
MyAppWeb.ApiSpec.spec()
|> Jason.encode!(pretty: true)
:ok = File.write!(output_file, json)
end
end
```
Generate the file with: `mix myapp.openapispec spec.json`
## Serve Spec
To serve the API spec from your application, first add the `OpenApiSpex.Plug.PutApiSpec` plug somewhere in the pipeline.
Once your API spec is available through a route, the `OpenApiSpex.Plug.SwaggerUI` plug can be used to serve a SwaggerUI interface. The `path:` plug option must be supplied to give the path to the API spec.
All JavaScript and CSS assets are sourced from cdnjs.cloudflare.com, rather than vendoring into this package.
```elixir
scope "/" do
pipe_through :browser # Use the default browser stack
get "/", MyAppWeb.PageController, :index
get "/swaggerui", OpenApiSpex.Plug.SwaggerUI, path: "/api/openapi"
OpenApiSpex can automatically validate requests before they reach the controller action function. Or if you prefer,
you can explicitly call on OpenApiSpex to cast and validate the params within the controller action. This section
describes the former.
First, the `plug OpenApiSpex.Plug.PutApiSpec` needs to be called in the Router, as described above.
Add the `OpenApiSpex.Plug.CastAndValidate` plug to a controller to validate request parameters, and to cast to Elixir types defined by the operation schema.
```elixir
plug OpenApiSpex.Plug.CastAndValidate
```
The `operation_id` can be inferred when used from a Phoenix controller from the contents of `conn.private`.
```elixir
defmodule MyAppWeb.UserController do
use MyAppWeb, :controller
alias OpenApiSpex.Operation
alias MyAppWeb.Schemas.{User, UserRequest, UserResponse}
plug OpenApiSpex.Plug.CastAndValidate
def open_api_operation(action) do
apply(__MODULE__, :"#{action}_operation", [])
end
def create_operation do
import Operation
%Operation{
tags: ["users"],
summary: "Create user",
description: "Create a user",
operationId: "UserController.create",
parameters: [
parameter(:id, :query, :integer, "user ID")
],
requestBody: request_body("The user attributes", "application/json", UserRequest),