Url changed when submit and surrounding issues - ruby-on-rails

Question

i'm newbie in Ruby on rails.
I'm doing CRUD for Articles and have a question: how to keep url and data's form when i create or update a article but it invalid validate?
And if they resolved, how to keep _form.html.erb to use for create and edit view.
I tried some solution in stackoverflow but there are no solution resolved all my problems above.
Here is new article view:
https://ibb.co/bdm4Hxj
You see, url change from /articles
https://ibb.co/wQ6Vxpz
inspect, we see action: /articles, method: post
https://ibb.co/LPJzvLr
and routes in rails:
https://ibb.co/rs1T1PY
_form.html.erb for create and edit view:
<%= form_for #article, html: {class: "form-horizontal"}, local: true do |f| %>
<div class="form-group">
<%= f.label :title, "Title", class: "col-md-2 control-label" %>
<div class="col-md-6">
<%= f.text_field :title, class: "form-control" %>
</div>
</div>
<div class="form-group">
<%= f.label :text, "Text", class: "col-md-2 control-label" %>
<div class="col-md-6">
<%= f.text_area :text, class: "form-control"%>
</div>
</div>
<div class="form-group">
<div class="col-lg-offset-4">
<a class="btn btn-success" href="<%= articles_path %>">Back</a>
<%= f.submit action_name.capitalize, class: "btn btn-success" %>
</div>
</div>
<% end %>
My ArticlesController:
class ArticlesController < ApplicationController
def index
#articles = Article.all
end
def new
#article = Article.new
end
def show
#article = get_by(:id)
end
def create
#article = Article.new(article_params)
if #article.save
flash[:success] = 'Create success!'
redirect_to articles_path
else
flash[:warning] = 'Something went wrong!'
render :new
end
end
def edit
#article = get_by(:id)
end
def update
#article = get_by(:id)
if #article.update(article_params)
flash[:success] = 'Update success!'
redirect_to articles_path
else
flash[:warning] = 'Update failed!'
render :edit
end
end
def destroy
#article = get_by(:id)
if #article.destroy
flash[:success] = 'Delete success!'
redirect_to articles_path
else
flash[:warning] = 'Delete failed!'
render :new
end
end
private
def article_params
params.require(:article).permit(:title, :text)
end
def get_by(id)
Article.find(params[id])
end
end
Thank you and sorry because of my bad english!

Answer 1

Your examples look pretty much what comes out of a scaffold, which is not too bad a start when learning how things can work (rails g scaffold article).
The relevant controller and views are then set up to do exactly what you are asking for: The controller holds a local variable (#article) ready for the view (ultimately _form.erb), whether or not the objects data is valid.
I wonder: What exactly happens? When you save with invalid data, the form should show up with the invalid data still in place. If you compare your form with the one that is created by the scaffold, you will notice that some output regarding validation errors is missing in your example. Try to add it, or start from scratch to see how it looks like.
When the data is valid and you still want the controller to show the user the form after hitting save, instead of redirect_to ... just render :edit.