Rails form_with results in a NoMethodError

问题:

I'm re-building a blog from the ground up and a ran into a problem concerning the form for creating new articles.

<%= form_with scope: :article, url: articles_path, local: true do |form| %> results in the error undefined method `form_with'.

Rails provides the following suggestion: Did you mean? form_tag

Upon trying form_tag, I get the following error: undefined method `label' for nil:NilClass

Form for new article using form_with

<h1>New Blog Post</h1>
<%= form_with scope: :article, url: articles_path, local: true do |form| %>
  <p>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
  </p>

  <p>
    <%= form.label :text %><br>
    <%= form.text_area :text %>
  </p>

  <p>
    <%= form.submit %>
  </p>
<% end %>

articles_controller.rb

class ArticlesController < ApplicationController
    def index
       @articles = Article.all 
    end

    def show
       @article = Article.find(params[:id]) 
    end

    def new
        @article = Article.new
    end

    def create
        @article = Article.new(article_params)

        @article.save
        redirect_to @article
    end

    private
        def article_params
            params.require(:article).permit(:title, :text)
        end
end

When I change form_with to form_tag I get the following error: undefined method `label' for nil:NilClass

For the record, I'm using

1. Ruby 2.3.4
2. Rails 4.2.5

回答1:

You want to use form_for @article do |form| (form_for Documentation, form_tag is used when you want a form tag (HTML tag) that's not necessarily attached to a ActiveRecord object.