How to Create a Middleware

[Code/Racer: Middleware] 0:00 In our last video, we saved the information from Facebook to our local database. 0:06 Now, let's go ahead and move that logic into a middleware. 0:11 Instead of doing if req.session.userid every single time we want to see if a user is logged in, 0:15 we can go ahead and create a middleware that will check on that for us. 0:23 We do that over here in our Application Definition. 0:27 I'm going to change the placement of these commas around very slightly 0:33 to make it easier to view. 0:36 In order to create a middleware, we do it right here inside of the express stack. 0:39 We send in the request, the response, and a callback called "next." 0:46 That will get called after the middleware has run. 0:52 What we'll do is check to see if there's a user id key inside of the session. 0:55 If there is, we'll find the user, 1:01 and we'll set a loggedIn variable inside of the request. 1:16 Then all we have to do is called req.loggedIn. 1:21 Then we call next to go back up the stack. 1:30 If there is no user, we set loggedIn to "False." 1:38 Finally, we need to do something in the event that there is no user ID in the session at all. 1:43 Now what we can do is change this down here in our "me" endpoint 1:56 to say if we're logged in. 2:05 All we have to do is render the template "me.eco" with our request user. 2:11 If not, we just redirect to the homepage. 2:24 Now we should see the exact same thing we saw last time 2:30 before we extracted it to a middleware, and we do, which is exactly what we want. 2:33 Finally, just for fun, let's go ahead and display our profile picture. 2:40 We do this inside of the instance methods. 2:45 We'll call this method avatar_url, 2:55 which is really just a link to Facebook. 3:10 Now let's display it inside of our view. 3:15 Right now we just have a link to the picture. 3:29 Let's go ahead and put it inside of an image tag. 3:31 And there we go. 3:44 In this video, we learned how to extract logic into a middleware, 3:46 thereby cleaning up our methods. 3:51