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How to Create a Middleware

3:54 with Jason Seifer

We can clean up our application a bit by extracting our sign in logic in to an Express middleware. This video shows how to both create a middleware and add some helper methods to our User class.

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    [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

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