[RUBY] [Rails] The cause of not being able to post was in form_with


Previously, a student who was creating something like twitter asked me, "I can't post even though I'm pressing a button! I don't get any error text! (Tears)." I had a hard time finding it, so I will post it for people with similar problems.


ruby 2.5.7

Cause and solution


def create
   @book = Book.new(book_params)
   @book.user_id = current_user.id
   if @book.save
      redirect_to book_path(@book)
      @books = Book.all
      render 'index'

... and if you can save to the controller, go to the book_path (@book) page! If you can't, go to the index page! Even though I have specified


<%= form_with model:book, url:root_path do |f| %>
<% end %>

... and go to the root_path page when the button is pressed in the view! Another mysterious designation was made.



<%= form_with model:book do |f| %>
<% end %>

If you delete all the url part of the view like ..., you can post without any problem. Congratulations.


If the description of the url part of form_with is incorrect, it may cause a routing error, so be careful.

If you want to know more about how to use form_with, we recommend the material here.

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