Updating an Associated Record

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 method and use those parameters to update our existing comment object. 5:53 Finally, we're going to need to show our updated comment object, 5:57 which we're going to want to do in the context of a post. 6:01 So we'll say redirect_to @post. 6:03 Remember that we set up the set_post before action, so 6:10 that's this @post instance variable. 6:14 Save that, and let's try editing that comment again. 6:16 Go here, we'll add a little more emphasis and we'll hit Update Comment and 6:22 you can see our edited comment here in the list on the post page. 6:27 So now we've got updating of a comment working as well. 6:32 The last thing we'll need is the ability to delete comments from a post. 6:35 We'll look at that next. 6:39