Select element in a nested form

Hi everyone,

I am getting an error when i try to add a select in a nested form

The error no function clause matching in Keyword.pop/3

My select code:

<div class="field">
  <%= label f, :category, class: "label" %>
  <div class="control">

    <%= select f, :category_id, @categories, fn cf -> %>
  <p class="help is-danger"><%= error_tag cf, :category %></p>
  <% end %>

Update link to form as suggested by @benwilson512

Update error trace

[info] GET /articles/new
[debug] Processing with
  Parameters: %{}
  Pipelines: [:browser]
[debug] QUERY OK source="categories" db=2.3ms
SELECT c0."id", c0."name", c0."slug", c0."inserted_at", c0."updated_at" FROM "categories" AS c0 []
[info] Sent 500 in 166ms
[error] #PID<0.840.0> running BlogApiWeb.Endpoint (connection #PID<0.839.0>, stream id 1) terminated
Server: localhost:4000 (http)
Request: GET /articles/new
** (exit) an exception was raised:
    ** (FunctionClauseError) no function clause matching in Keyword.pop/3
        (elixir) lib/keyword.ex:977: Keyword.pop(#Function<2.44023343/1 in BlogApiWeb.ArticleView."form.html"/1>, :value, nil)
        (phoenix_html) lib/phoenix_html/form.ex:1117: Phoenix.HTML.Form.selected/3
        (phoenix_html) lib/phoenix_html/form.ex:1099:
        (blog_api) lib/blog_api_web/templates/article/form.html.eex:29: anonymous fn/2 in BlogApiWeb.ArticleView."form.html"/1
        (phoenix_html) lib/phoenix_html/form.ex:377: Phoenix.HTML.Form.form_for/4
        (blog_api) lib/blog_api_web/templates/article/form.html.eex:1: BlogApiWeb.ArticleView."form.html"/1
        (blog_api) lib/blog_api_web/templates/article/new.html.eex:3: BlogApiWeb.ArticleView."new.html"/1
        (blog_api) lib/blog_api_web/templates/layout/app.html.eex:15: BlogApiWeb.LayoutView."app.html"/1
        (phoenix) lib/phoenix/view.ex:410: Phoenix.View.render_to_iodata/3
        (phoenix) lib/phoenix/controller.ex:729: Phoenix.Controller.__put_render__/5
        (phoenix) lib/phoenix/controller.ex:746: Phoenix.Controller.instrument_render_and_send/4
        (blog_api) lib/blog_api_web/controllers/article_controller.ex:1: BlogApiWeb.ArticleController.action/2
        (blog_api) lib/blog_api_web/controllers/article_controller.ex:1: BlogApiWeb.ArticleController.phoenix_controller_pipeline/2
        (phoenix) lib/phoenix/router.ex:288: Phoenix.Router.__call__/2
        (blog_api) lib/blog_api_web/endpoint.ex:1: BlogApiWeb.Endpoint.plug_builder_call/2
        (blog_api) lib/plug/debugger.ex:122: BlogApiWeb.Endpoint."call (overridable 3)"/2
        (blog_api) lib/blog_api_web/endpoint.ex:1:
        (phoenix) lib/phoenix/endpoint/cowboy2_handler.ex:42: Phoenix.Endpoint.Cowboy2Handler.init/4
        (cowboy) /home/dan/Codes/blog_api/deps/cowboy/src/cowboy_handler.erl:41: :cowboy_handler.execute/2
        (cowboy) /home/dan/Codes/blog_api/deps/cowboy/src/cowboy_stream_h.erl:320: :cowboy_stream_h.execute/3

Update article controller

Update migrations for articles and categories

Schemas and contexts

Also if there are any suggestions for the rest of my code the full code here
Thanks in advance

Please provide the full stack trace of the error, and it would probably help to link to the form within that code base.

1 Like

Thanks @benwilson512 for the suggestion I added more info. is the issue, it isn’t valid to pass a function to select.

OK so I use the nested without passing a fn then?

I’m not really sure I understand why you need a nested form at all. :category_id is a field of the changeset. Nested forms are necessary when you are editing a value AND an associated (or embedded) value. Your form only messes with the top level changeset.

Either way, select does not create a nested form, you want inputs_for for that.

Thanks I will check it out

Also to answer to you questions

I thought that this is the best way to achive what i wanted. But if it is not then please recommend a better way I have created this project to learn and understand phoenix so i am very open to any suggestions you might have.

Thanks again for helping me with this.

If what you want is to edit the category_id field, just treat it like the :title field.

<%= select f, :category_id, @categories %>
<p class="help is-danger"><%= error_tag f, :category %></p>
1 Like