Json View problem - Could not render / please define a matching clause for render/2 or define a template

wernerlaude

I try to render a view as json.
router:

pipeline :api do
  plug :accepts, ["json"]
end

scope "/api", MyAppWeb do
 pipe_through :api

 get "/networking", PageController, :networking
end

controller:

def networking(conn, _params) do
 q = from m in Meeting, where: m.is_active == true
 meetings = Repo.all(q)
  render(conn, "networking.json", meetings: meetings)
end

view:

def render("networking.json", %{meetings: meetings}) do
 %{data: render_many(meetings, PageView, "networking.json")}
end

def render("networking.json", %{meeting: meeting}) do
   %{id: meeting.id,
   title: meeting.title}
end

But I get: Could not render "networking.json for MyAppWeb.PageView, please define a matching clause for render/2 or define a template…
Did I forget something? Thanks for support.

24 comments

/phoenix #json #troubleshooting

1 5886 24

2019-12-03 18:33:02 UTC

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mbuhot

Just a guess, do the controller and view names match?

Post #1

wernerlaude

Think so..

page_controller.ex

defmodule MyAppWeb.PageController do
  use MyAppWeb, :controller

page_view.ex

defmodule MyAppWeb.PageView do
  use MyAppWeb, :view

  alias MyAppWeb.PageView

def render("networking.json", %{meetings: meetings}) do
  %{data: render_many(meetings, PageView, "networking.json")}
end

def render("networking.json", %{meeting: meeting}) do
   %{id: meeting.id,
   title: meeting.title}
end

It is not all clear to me what is happening here, I applied it from a sample..

Post #2

acrolink

Make sure you have this inside myapp_web/endpoint.ex file:

  plug Plug.Parsers,
    parsers: [:urlencoded, :multipart, :json],
    pass: ["*/*"],
    json_decoder: Poison

  plug Plug.MethodOverride
  plug Plug.Head

Post #3

benwilson512

Author of Craft GraphQL APIs in Elixir with Absinthe

Can you provide the full error stack trace?

Post #4

acrolink

I guess the problemscan be solved like this:

def render("index.json", %{meetings: meetings}) do
  %{data: render_many(meetings, PageView, "networking.json")}
end

def render("networking.json", %{meeting: meeting}) do
   %{id: meeting.id,
   title: meeting.title}
end

and in controller:

render(conn, "index.json", meetings: meetings)

Post #5

wernerlaude

thanks.. is in..

Post #6

wernerlaude

[error] pid<0.559.0> running MyAppWeb.Endpoint (cowboy_protocol) terminated
Server: localhost:4000 (http)
Request: GET /api/networking
** (exit) an exception was raised:
** (Phoenix.Template.UndefinedError) Could not render “networking.json” for MyAppWeb.PageView, please define a matching clause for render/2 or define a template at “lib/my_app_web/templates/page”. The following templates were compiled:

dashboard.html
etc..

Post #7

benwilson512

Author of Craft GraphQL APIs in Elixir with Absinthe

I really did mean the full thing. Do you have a plug accepts json in your router?

Post #8

kokolegorille

The plug is here as it is defined in the router in the OP.

I would try to add a catch all clause in the view, just to see what params are sent. Like so…

def render("networking.json", params) do
   IO.inspect params
end

Post #9

wernerlaude

ok.. thanks so far
so code is like that now:

router

scope "/api", MyAppWeb do
  pipe_through :api
  get "/networking", PageController, :networking
end

view

defmodule MyAppWeb.PageView do
  use MyAppWeb, :view

  alias MyAppeb.PageView

  def render("networking.json", params) do
   IO.inspect params
  end

page_controller

def networking(conn, _params) do
  q = from m in Meeting, where: m.is_active == true, order_by: m.inserted_at
  meetings = Repo.all(q)
 render(conn, "networking.json", meetings: meetings)
end

error:
Poison.EncodeError at GET /api/networking
unable to encode value: {Plug.Adapters.Cowboy.Conn, {:http_req, port<0.23603>, :ranch_tcp, :keepalive, pid<0.1093.0>, “GET”, :“HTTP/1.1”, {{127, 0, 0, 1}, 57166}, “localhost”, :undefined, 4000, “/api/networking”, :undefined, “”, :undefined, , [{“host”, “localhost:4000”}, {“connection”, “keep-alive”}, {“upgrade-insecure-requests”, “1”}, {“user-agent”, “Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36”}, {“accept”, “text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/;q=0.8”}, {“accept-encoding”, “gzip, deflate, br”}, {“accept-language”, “de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7,la;q=0.6”}, {“cookie”, “Webstorm-f9c6b724=b25b909c-75d4-46de-9b31-cded003fdbfa; _ga=GA1.1.424741732.1519378781; Webstorm-f9c6bae3=1e19a62a-70f2-445c-b2dd-b6a425eab18a; axd=1000215891540480040; cookieconsent_dismissed=yes; __utma=111872281.424741732.1519378781.1528479627.1528479627.1; __utmz=111872281.1528479627.1.1.utmcsr=0.0.0.0:3000|utmccn=(referral)|utmcmd=referral|utmcct=/; cookieconsent_status=dismiss; _tiny_houses_net_key=SFMyNTY.g3QAAAACbQAAAAtfY3NyZl90b2tlbm0AAAAYd1pKK05WUmJFNnlScTJ3dllLTWsrQT09bQAAABJwaGF1eHRoX3Nlc3Npb25faWRtAAAAEkZsRXRKdmZSQ2RZNmsxWWZkMQ.lqyimMwpF0DhHsjSA7mJlAKTQyGUz_1weRtsTAZCuzE”}], [{“connection”, [“keep-alive”]}], :undefined, , :waiting, “”, :undefined, false, :waiting, , “”, function<1.79365245/4 in Plug.Adapters.Cowboy.add_on_response/3>}}