Deleting Pages

[MUSIC] 0:00 We can add new wiki pages show pages we've added and then update them. 0:04 The only thing missing now is the ability to delete pages. 0:08 Let's add that now. 0:12 Our wiki.rb file has a page_content method that loads the contents of a text file and 0:13 a save_content method that saves a file. 0:18 I've added another method called delete_content which deletes a file from 0:22 the pages directory. 0:26 It simply calls the File.delete method which takes the name of a file to delete. 0:27 If you launch a work space from this video's page, 0:33 you'll get a wiki.rb file with this method already set up for you. 0:34 This time I'll leave testing the method up to. 0:39 If you want to experiment with delete content, you can copy it to a separate 0:41 file and add a call to it with the name of a file in your pages directory to delete. 0:44 You may need to refresh the sidebar before you can see the changes. 0:48 Now we just need a way for users to call this method with a particular page title. 0:52 Let's set up a button on each wiki page that lets users send a request 0:56 to delete that page. 1:00 There's one more commonly used request type that Sinatra recognizes and 1:01 that's delete request. 1:05 But as with put requests, 1:07 there's no way to send a delete requests from plain HTML links or forms. 1:08 As with put the best way is to create an HTML form and 1:12 use a hidden underscore method parameter with a value of delete. 1:15 We won't add any text fields to this form, 1:19 it's just going to consist of a single delete button. 1:21 In the show.erb template, let's add a form element. 1:23 We're going to place it within the div element so 1:29 that it's easier to style it later. 1:31 As before, the only requests type supported by HTML are get and post, so 1:35 we'll set the form's method attribute to post. 1:40 Then within the form, will add an input element with the type of hidden. 1:44 It'll have a name of _method And a value of delete. 1:53 That will cause Sinatra to delete the form submission as delete request. 2:02 As with all the other requests types, delete request need a path to act on. 2:06 We'll set that by adding an action attribute to the form tag. 2:09 We'll give it the path of the wiki page we're trying to delete. 2:14 That is a slash followed by the page title which will embed using an erb tag. 2:17 As before, we can reuse the title instance variable which is already used elsewhere 2:22 in the template. 2:26 Lastly, we'll need the button that users will click to submit the requests. 2:27 Will add an input element with a type of submit. 2:31 The value attribute determines what the button will be labeled. 2:37 So we'll give it a value of delete this page. 2:42 Let's start up our server and run a preview. 2:46 And now let's view a wiki page. 2:51 We'll see a new Delete This Page button at the bottom. 2:55 If we click that button, 3:00 we'll see Sinatra doesn't know this ditty again because there's no matching route. 3:01 At the bottom of the page, 3:05 we'll see a recommendation to create a route using a method named delete. 3:06 That means our form submission is being treated as a delete request. 3:10 Now we just need to edit our wiki.rb file and add a delete route. 3:15 Again, order doesn't matter. 3:19 There's no way a delete request will accidentally be matched by 3:20 our route's forget, post or put requests. 3:23 Just as a method to set up a route for get requests is called GET and the method for 3:27 post routes is called POST the method for delete routes is called Delete. 3:31 So we'll add a call to that method now. 3:36 And you probably know what comes next by now, the path to match. 3:37 We set up our form to submit to a path of a slash followed by the current 3:42 page title. 3:45 So that's what will match here a slash followed by a URL parameter for the title. 3:46 And of course we need a block to invoke when the routers match. 3:52 In that block, what we'll have to do is call our delete_content method 3:58 with the page title and it will delete the appropriate text file for us. 4:01 So, we'll call delete_content and give it the title from the URL parameter. 4:05 We'll also need to redirect the browser to another page, so 4:12 we'll call the redirect method. 4:15 We'll just redirect them to the root path. 4:19 There's no need to call URI dot escape on the redirect path this time 4:22 since there's no chance of it containing an invalid character. 4:25 Save that. 4:29 Let's restart our server. 4:30 And go back to the home page. 4:36 We'll create a new page to test our delete functionality out on. 4:37 We'll use the title of John Doe and text of just some guy. 4:42 Submit it. 4:50 And if we go back to our workspace and refresh the file sidebar, 4:51 We'll see John Doe.text here in the page's directory. 4:57 If we go back to the new page and 5:00 click delete, we'll be redirected back to the root path. 5:02 And if we refresh our workspace sidebar again, we'll see if 5:08 the John Doe.text file has been deleted. 5:13