How do I get path parameters in LiveView?

Hentioe

My router:

live "/cities/:id/users", CityLive

I tried the handle_params function but it was never called:

def handle_params(%{"id" => id}, _uri, socket) do
  # some code
end

I tried to follow the practice in the chrismccord/phoenix_live_view_example project and still failed (session is always %{})：

def mount(%{path_params: %{"id" => id}}, socket) do
  # some code
end

Can see the parameters from the log:

Can anyone tell me what is missing?

14 comments

/phoenix #liveview

1 11057 14

2020-02-14 14:13:28 UTC

Showing Posts 1 to 10

Show Best Posts
Show All (oldest first)
Show All (newest first)

LostKobrakai

If your liveview is mounted in the router and is the root one (not nested) it should work with handle_params. I did use that a few days ago. If that‘s not the case you should be able to supply the param as part of the session data you supply for live_render.

Post #1

benwilson512

Author of Craft GraphQL APIs in Elixir with Absinthe

You need to specify path_params as part of the live route session:

live "/cities/:id/users", CityLive,
  session: [:path_params]

Post #2

Hentioe

I still have not succeeded. path_params is always nil.

Post #3

chrismccord

Creator of Phoenix

You can only receive path params via the handle_params/3 callback, and handle_params is only invoked for the root LV. If you are trying to get path params to a child, you need to retrieve them from the root and pass them down to the children via assigns in the parent

Post #4

Hentioe

Maybe I misunderstood what? This is the root LV, which is not loaded from the parent LV. I can get the query parameters of the same level LV from handle_params, but I can’t get the path parameters.

The code is at:
https://github.com/elixirchina/community/blob/a86bb0c89bf158ead69d733a9d14a022ec28d6a9/lib/community_web/router.ex#L23

Thanks for the reply from the author!

Post #5

chrismccord

Creator of Phoenix

The params contain the merged path params and query param so “id” should be there. Can you provide the entire LV?

Post #6

Hentioe

I made a mistake, sorry! A very small mistake! This problem is invalid

Post #7

Hentioe

This problem does not exist because I wrote the wrong number of handle_params parameters.

Thank you all

Post #8

homanchou

I too am tripped up by this. Maybe the GitHub - chrismccord/phoenix_live_view_example · GitHub for CRUD user are out of date and need to be updated?

For example on: phoenix_live_view_example/lib/demo_web/live/user_live/show.ex


  def mount(%{path_params: %{"id" => id}}, socket) do
    if connected?(socket), do: Demo.Accounts.subscribe(id)
    {:ok, fetch(assign(socket, id: id))}
  end

will break on localhost:4000/users/1 with error: no function clause matching in DemoWeb.UserLive.Show.mount/2 because the received first arg %{} can never match %{path_params: %{"id" => id}}

If the recommendation is to now use handle_params/3 to get the path_params, (which handle_params/3 is called sometime after mount/2) does that mean that it is not possible to fetch the User data in mount/2 for the first render?

Post #9