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Edit GS guide § Updating an Article [ci-skip] 

Fixes #39920.
Resolves #38329.

Co-Authored-By: Ryan Bigg <me@ryanbigg.com>
Co-Authored-By: Petrik de Heus <petrik@deheus.net>
This commit is contained in:
Jonathan Hefner 2020-10-28 17:03:17 -05:00
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@ -1062,180 +1062,75 @@ To finish up, let's link to that page from the bottom of
<%= link_to "New Article", new_article_path %> <%= link_to "New Article", new_article_path %>
``` ```
### Updating Articles ### Updating an Article
We've covered the "CR" part of CRUD. Now let's focus on the "U" part, updating We've covered the "CR" of CRUD. Now let's move on to the "U" (Update). Updating
articles. a resource is very similar to creating a resource. They are both multi-step
processes. First, the user requests a form to edit the data. Then, the user
submits the form. If there are no errors, then the resource is updated. Else,
the form is redisplayed with error messages, and the process is repeated.
The first step we'll take is adding an `edit` action to the These steps are conventionally handled by a controller's `edit` and `update`
`ArticlesController`, generally between the `new` and `create` actions. Let's add a typical implementation of these actions to
actions, as shown: `app/controllers/articles_controller.rb`, below the `create` action:
```ruby ```ruby
def new class ArticlesController < ApplicationController
@article = Article.new def index
end @articles = Article.all
def edit
@article = Article.find(params[:id])
end
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end end
end
```
NOTE: We're using `edit` to render a view. For the actual def show
saving of the changes to the Article, we'll add an `update` action later. @article = Article.find(params[:id])
The view will contain a form similar to the one we used when creating
new articles. Create a file called `app/views/articles/edit.html.erb` and make
it look as follows:
```html+erb
<h1>Edit Article</h1>
<%= form_with model: @article, local: true do |form| %>
<% if @article.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(@article.errors.count, "error") %> prohibited
this article from being saved:
</h2>
<ul>
<% @article.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<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 %>
<%= link_to 'Back', articles_path %>
```
This time we point the form to the `update` action, which is not defined yet
but will be very soon.
Passing the article object to the `form_with` method will automatically set the URL for
submitting the edited article form. This option tells Rails that we want this
form to be submitted via the `PATCH` HTTP method, which is the HTTP method you're
expected to use to **update** resources according to the REST protocol.
Also, passing a model object to `form_with`, like `model: @article` in the edit
view above, will cause form helpers to fill in form fields with the corresponding
values of the object. Passing in a symbol scope such as `scope: :article`, as
was done in the new view, only creates empty form fields.
More details can be found in [form_with documentation]
(https://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#method-i-form_with).
Next, we need to create the `update` action in
`app/controllers/articles_controller.rb`.
Add it between the `create` action and the `private` method:
```ruby
def edit
@article = Article.find(params[:id])
end
def create
@article = Article.new(article_params)
if @article.save
redirect_to @article
else
render 'new'
end end
end
def update def new
@article = Article.find(params[:id]) @article = Article.new
if @article.update(article_params)
redirect_to @article
else
render 'edit'
end end
end
private def create
def article_params @article = Article.new(article_params)
params.require(:article).permit(:title, :text)
if @article.save
redirect_to @article
else
render :new
end
end end
def edit
@article = Article.find(params[:id])
end
def update
@article = Article.find(params[:id])
if @article.update(article_params)
redirect_to @article
else
render :edit
end
end
private
def article_params
params.require(:article).permit(:title, :body)
end
end
``` ```
The new method, `update`, is used when you want to update a record Notice how the `edit` and `update` actions resemble the `new` and `create`
that already exists, and it accepts a hash containing the attributes actions.
that you want to update. As before, if there was an error updating the
article we want to show the form back to the user.
We reuse the `article_params` method that we defined earlier for the create The `edit` action fetches the article from the database, and stores it in
action. `@article` so that it can be used when building the form. By default, the `edit`
action will render `app/views/articles/edit.html.erb`.
TIP: It is not necessary to pass all the attributes to `update`. For example, The `update` action (re-)fetches the article from the database, and attempts
if `@article.update(title: 'A new title')` was called, Rails would only update to update it with the submitted form data filtered by `article_params`. If no
the `title` attribute, leaving all other attributes untouched. validations fail and the update is successful, the action redirects the browser
to the article's page. Else, the action redisplays the form, with error
Finally, we want to show a link to the `edit` action in the list of all the messages, by rendering `app/views/articles/edit.html.erb`.
articles, so let's add that now to `app/views/articles/index.html.erb` to make
it appear next to the "Show" link:
```html+erb
<table>
<tr>
<th>Title</th>
<th>Text</th>
<th colspan="2"></th>
</tr>
<% @articles.each do |article| %>
<tr>
<td><%= article.title %></td>
<td><%= article.text %></td>
<td><%= link_to 'Show', article_path(article) %></td>
<td><%= link_to 'Edit', edit_article_path(article) %></td>
</tr>
<% end %>
</table>
```
And we'll also add one to the `app/views/articles/show.html.erb` template as
well, so that there's also an "Edit" link on an article's page. Add this at the
bottom of the template:
```html+erb
...
<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>
```
And here's how our app looks so far:
![Index action with edit link](images/getting_started/index_action_with_edit_link.png)
### Using partials to clean up duplication in views ### Using partials to clean up duplication in views