How to check the arguments of the auto generated Phoenix paths - phoenix-framework

Question

No helper clause for Api.Router.Helpers.v1_user_organization_path
defined for action :show with arity 3. Please check that the function,
arity and action are correct. The following v1_user_organization_path
actions are defined under your router:
* :create
* :index
* :show
* :update
router.ex
defmodule Api.Router do
use Api.Web, :router
pipeline :api do
plug :accepts, ["json"]
end
scope "/", Api do
pipe_through :api
end
scope "/v1", Api.V1, as: :v1 do
pipe_through :api
resources "/users", UserController, only: [:create, :show, :update] do
resources "/organizations", OrganizationController, only: [:create, :update, :index, :show]
end
end
end
and when I do mix phoenix.routes I see the following v1_user_organization_path getting generated. The problem is I don't know how to use it and I don't know what I should pass into it. Is there a way I can check what this generated method accepts?
The error I get is occuring here
organization_controller.ex
def create(conn, %{"user_id" => user_id, "organization" => organization_params}) do
changeset = Organization.changeset(%Organization{}, organization_params)
case Repo.insert(changeset) do
{:ok, organization} ->
conn
|> put_status(:created)
|> put_resp_header("location", v1_user_organization_path(conn, :show, organization))
|> render("show.json", organization: organization)
{:error, changeset} ->
conn
|> put_status(:unprocessable_entity)
|> render(Api.ChangesetView, "error.json", changeset: changeset)
end
end
At put_resp_header("location", v1_user_organization_path(conn, :show, organization))

Answer 1

You can look at the auto generated documentation for the router helper functions using h in iex -S mix and reading the output of mix phoenix.routes for some help. For example, for the following routes:
resources "/posts", PostController do
resources "/comments", CommentController
end
I get:
iex(1)> h MyApp.Router.Helpers.post_comment_path
def post_comment_path(conn_or_endpoint, action, post_id)
def post_comment_path(conn_or_endpoint, action, post_id, params)
def post_comment_path(conn_or_endpoint, action, post_id, id, params)
$ mix phoenix.routes
post_comment_path GET /posts/:post_id/comments MyApp.CommentController :index
post_comment_path GET /posts/:post_id/comments/:id/edit MyApp.CommentController :edit
post_comment_path GET /posts/:post_id/comments/new MyApp.CommentController :new
post_comment_path GET /posts/:post_id/comments/:id MyApp.CommentController :show
post_comment_path POST /posts/:post_id/comments MyApp.CommentController :create
post_comment_path PATCH /posts/:post_id/comments/:id MyApp.CommentController :update
PUT /posts/:post_id/comments/:id MyApp.CommentController :update
post_comment_path DELETE /posts/:post_id/comments/:id MyApp.CommentController :delete
It's not clear from just the function signature which action accepts how many arguments, but if you read the output of mix phoenix.routes, you can see that :show (last column) requires a post_id and an id.
The output of h is also not completely accurate because it doesn't tell you that the arity 4 version also accepts (conn_or_endpoint, action, post_id, id) and not just (conn_or_endpoint, action, post_id, params).
I don't think there's any better auto generated documentation for the generated route functions right now in Phoenix. I usually just look at the output of mix phoenix.routes and pass in conn_or_endpoint followed by the action followed by every :var in the route, optionally followed by a params map.