URL Parameters

We're set up to load page content from text files. 0:00 Next we need to display that content in the browser. 0:03 We want people to be able to type in a path and 0:06 see the contents of a text file that was loaded in from the pages directory. 0:08 Let's add directions to the welcome paid so that people know to try this, 0:13 we'll let it welcomed the RB in the views directory and 0:18 will add in an age female paragraph with our directions Visit 0:22 /PageName, To view a page. 0:27 Save that, and now if we run the app. 0:35 And reload the route path, we'll see those directions. 0:41 But if we try that now by clicking in the address bar and typing in Nick Pettit. 0:45 Remember that's the name of the sample text file we created. 0:53 We see Sinatra doesn't know that steady. 0:56 By the way notice that the space in the URL gets replaced with a %20. 0:59 Space characters aren't valid in a URL so the browser encodes them. 1:04 Sinatra still gets the space character in the browser requests though 1:08 we want to be able to type in slash Nick Pettit or slash robots or 1:12 any other page we've created the text file for and have it load, but 1:16 there's no way we can create separate Sinatra outs for all those. 1:19 Not only would our app code be really long, 1:23 we can't possibly anticipate every page that users might want to create. 1:25 So instead, we're going to create a single route that will match 1:30 any page users might attempt to visit. 1:32 And we'll do it using a URL parameter. 1:35 A URL parameter allows users to substitute any string they want for 1:38 part of the request path. 1:42 That string will then be accessible within your Sinatra route. 1:44 First let's set up a route with a URL parameter. 1:47 We want this to respond to HTTP get requests. 1:50 So we'll use the get method as we did before. 1:53 So we'll go here into wiki.rb then copy get method. 1:58 Then we need a path to match. 2:03 Paths always start with the slash. 2:05 So we'll set that up in a string. 2:07 The next segment of the path will be our URL parameter. 2:10 Parameters are marked with a colon followed by a parameter name. 2:13 We want this parameter to be the title of the page we want to view. 2:16 So, we'll call it title, :title. 2:20 And as always the route needs a block to call when it gets a matching request. 2:25 Let's set the route up so that we can look at the parameter we're getting 2:32 from the URL parameters gets stored along with other parameters in the params hash. 2:35 You can access params within any Sinatra route block. 2:41 The keys of the params hash are the names of the parameters you can use either 2:44 a symbol or a string whichever you prefer both will access the same parameter. 2:48 So to access the title parameter we give it the symbol, title as a key. 2:53 Our title URL parameter is now the return value of the block. 2:59 So that's what will be returned in the response to the browser. 3:02 Let's save our work, restart our app. 3:06 And then reload the preview for the /NickPettit URL. 3:12 We can see that it takes the string from the request path 3:17 along with the encoded space character. 3:20 Puts it into the title URL parameter and then prints that parameter out. 3:22 Now that we've got a page title, we can pass it to the page content method to load 3:27 text files from the pages directly. 3:31 So, instead of just returning the title parameter, we'll pass it to page content 3:34 as an argument, page_content (params(:title): will be our new argument. 3:38 And since that's the last expression on the block, 3:47 the page text will be the new return value. 3:49 Let's restart the app again. 3:52 And reload our preview page. 3:57 Instead of the Nick Pettit title parameter we'll see the content 4:00 of the text from the page's directory. 4:03 This page is a little bare bones though. 4:06 We're just dumping raw text in the response instead of HTML. 4:08 We're not displaying the page title anywhere. 4:11 So, up next, we'll show you how to use ZR beat to embed the title and 4:14 text into an HTML template. 4:17