function Map.put/4 is undefined or private

user_17928433 0
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I just started to learn elixir and phoenix.

I am trying to add comments to blog but i got this error

function Map.put/4 is undefined or private

Error is in this line (show.html.heex):

<%= render "comment_form.html", Map.put(assigns, :changeset, :action, Routes.post_post_path(@conn, :add_comment, @post)) %>

My code in post_controller.ex

  def show(conn, %{"id" => id}) do
      post =
          id
            |> Posts.get_post!
            |> Repo.preload([:comments])

      changeset = Comment.changeset(%Comment{}, %{})
      render(conn, "show.html", post: post, changeset: changeset)
  end

And comment_form.html.heex

<%= form_for @changeset, @action, fn f -> %>
    <div class="form-group">
        <label>Name</label>
        <%= text_input f, :name, class: "form-control" %>
    </div>
    <div class="form-group">
        <label>Content</label>
        <%= textarea f, :content, class: "form-control" %>
    </div>
    <div class="form-group">
        <%= submit "Add comment", class: "btn btn-primary" %>
    </div>
<% end %>
phoenix-framework elixir web backend
1 Answers

You may have accidently added :changeset in the code:

- Map.put(assigns, :changeset, :action, Routes.post_post_path(@conn, :add_comment, @post))
+ Map.put(assigns, :action, Routes.post_post_path(@conn, :add_comment, @post))

Map.put/3 can put a new key-value pair into an existing map. Here 3 means the arity (the number of arguments) is 3.

In your case, it makes little sense to put a new assign of :changeset into the inherited assigns which already contain that key.

user_43876410
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