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