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Updating an Associated Record

Name: Updating an Associated Record
Uploaded: 2017-10-28T21:28:45Z
Duration: 400 s
Description: We've added a way to create comments that belong to a post. Now let's add a means of updating those comments.

6:40 with Jay McGavren

We've added a way to create comments that belong to a post. Now let's add a means of updating those comments.

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We've added a way to create comments that belong to a post. Now let's add a means of updating those comments.

We want an "edit" link to appear next to each comment.
We'll get that by editing the _comment partial.

views/comments/_comment.html.erb

<div class="comment-admin">
  <%= link_to "Edit", edit_post_comment_path(@post, comment) %>
</div>

Next we need an edit action on the CommentsController:

controllers/comments_controller.rb

  def edit
    @post = Post.find(params[:post_id])
    @comment = Comment.find(params[:id])
  end

@post = Post.find(params[:post_id]) code is repeated between create and edit actions, and we'll need @post for other actions
Use before_action to set @post

class CommentsController < ApplicationController
  before_action :set_post
  def create
    @comment = @post.comments.create(comment_params)
    redirect_to @post
  end
  def edit
    @comment = Comment.find(params[:id])
  end
  private
  def comment_params
    params.require(:comment).permit(:name, :content)
  end
  def set_post
    @post = Post.find(params[:post_id])
  end
end

When we click the "Edit" link, it calls our edit action, but there's no view. So let's create one:

views/comments/edit.html.erb

<h1>Edit Comment</h1>
<%= render partial: "form", locals: {comment: @comment} %>

We need an update action on CommentsController so we can submit the form:

  def update
    @comment = Comment.find(params[:id])
    @comment.update(comment_params)
    redirect_to @post # @post will be set by before_action
  end

We've added a way to create comments that belong to a post. 0:00

Now let's add a means of updating those comments. 0:03

We're going to want an edit link to appear next to each comment in the list. 0:06

We'll get that by editing the comment partial. 0:10

So we'll go here to our views directory > comments sub-directory, and 0:13

we'll edit the comment partial. 0:17

Here within the main comment div we're going to add a new div, and 0:19

we'll give it a class of comment admin. 0:24

Should be useful later, we're not going to use it right now. 0:28

Close out the div. 0:33

And now to set up our link. 0:36

We'll insert an erb tag, with a call to the link_to method. 0:37

We're going to want the link text to read Edit, as in edit the current comment. 0:43

And now we need to provide the path that the link is going to point to. 0:48

We're going to call edit_post_comment_path. 0:51

And this call is going to need multiple parameters. 0:58

First, it's going to need a post to provide the ID used in the post ID URL 1:01

parameter. 1:05

So we'll get that by providing the post object that's in the post instance 1:06

variable. 1:10

Then it's going to need a common ID that it's going to edit. 1:12

You can get that by providing the common metal object that's in the common 1:15

local variable. 1:20

Close out the erb tag and save that, and 1:23

let's refresh our browser and there are our edit links. 1:26

But if we click on it, 1:31

we'll see the action edit could not be found on the CommentsController. 1:32

So we're gonna need to go to our comment controller and add that action. 1:37

So we'll define and edit method. 1:45

And again, we're going to need the post that the comment belongs to. 1:51

So we'll assign to the post instance variable 1:54

the result of calling Post.find with the parameter 1:59

post_id, which it'll get from the URL. 2:05

Then we're also going to need the comment that we're working with, 2:11

which will assign to the comment instance variable. 2:14

And that will be the result, we'll call it comment.find with the ID parameter. 2:17

Let's save this and try reloading. 2:25

Visit the edit link again. 2:30

And it looks like it's getting to the edit action successfully. 2:33

We don't have a view to render for this action right now, 2:36

but we'll take care of that momentarily. 2:38

There's another issue I want to address first. 2:41

Notice that this post = Post.find(params[post_id]) code is 2:44

repeated between both the create and edit methods. 2:48

And we're going to need our post instance variable set for other actions, too. 2:52

Let's go ahead and cut this code out of there and 2:56

add a private method named set post. 3:00

Paste in there. 3:06

Then we can remove that code from our edit method as well. 3:11

And we can set set_post up to be called as a before_action on the controller. 3:17

Now before both our create and edit actions run this set_post method will 3:29

be called and the post instance variable will be set. 3:34

Let's save that now let's get back to our original problem. 3:40

Only click on the edit link, it calls our edit action but 3:43

there's no view for it to render. 3:47

So let's go and create that now. 3:50

We'll go into the views comments controller and 3:52

we're going to create a new file, named edit.html.erb. 3:56

We'll add a heading saying what we're doing on this page. 4:01

We're editing a comment. 4:03

And because we already have our form partial, 4:08

all we have to do is call render with that partial. 4:10

So we'll say render partial form and 4:14

all we have to do is say form. 4:19

We don't have to specify what directory it's contained. 4:22

Since it's in the same directory as this edit few. 4:26

And then we need to set up the comment local variable. 4:29

So we'll say Locals Comment and we're going to set 4:32

that equal to our comments instance variable. 4:38

Save that and let's go back to our post view and 4:42

try editing a comment again. 4:47

And this time the edit template is called which in turn calls the form partial. 4:51

So let's make a little change to this, we will add a little more emphasis on 4:56

the comment content, and now let's try submitting the form. 5:00

We get the error that there's no update action on our comments controller, so 5:04

let's add that now. 5:08

We'll add a method named update. 5:13

And first, we're going to need to find the comment that we're working with. 5:18

So we'll assign to the comment instance variable 5:21

the result of calling Comment.find the id parameter. 5:27

Then we need to update this comment with our comment parameters. 5:37

So we'll say comment.update comment_params. 5:40

And as it does when we're creating a new comment, it'll call the comment params 5:48

Active Record Associations in Rails

Updating an Associated Record