1 parameter not saving on create-CodePudding

I have a 'parent_id' which is successfully passed as parameter into a form page ("Create Child") here :

<li><%= link_to "Create Child", new_block_path(:parent_id => @block.id)%></li>

Logging the parameter gives :

Started GET "/blocks/new?parent_id=7" for ::1 at 2022-10-31 22:01:05  0000
Processing by BlocksController#new as HTML
  Parameters: {"parent_id"=>"7"}

I then have a form which calls a create method here :

def create
    @block = Block.new(block_params)

    if @block.save
      redirect_to @block
    else
      render :new, status: :unprocessable_entity
    end
  end

using these block_params

private 
    def block_params
      params.require(:block).permit(:title, :body, :parent_id)
    end
  end

But when I call the create function only :title and :body are present.

Printing the parameters shows :

Started POST "/blocks" for ::1 at 2022-10-31 22:01:17  0000
Processing by BlocksController#create as TURBO_STREAM
Parameters: {"authenticity_token"=>"[FILTERED]", 
"block"=>{"title"=>"this is a child of block 7", 
"body"=>"this is a child of block 7"}, "commit"=>"Create Block"}

Filtered shows :title and :body are permitted correctly, but the URL parameter of parent_id has just vanished.

The rails guide states : "Submitted form data is put into the params Hash, alongside captured route parameters" - I just can't work this out. The parent_id parameter is there as it should be when the form is loaded, but when submitted it vanishes.

CodePudding user response：

There are two actions, new and create, you could think they are separate.

So params from new won't be available in create automatically (in your case parent_id), you have to pass the params explicitly.

You could just add a hidden input in your form to pass parent_id:

<%= form_with model: @block do |f| %>
  <%= f.hidden_field :paren_id, value: params[:parent_id] %>
  <%= f.text_field :title %>
  <%= f.text_field :body %>
<% end %>