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PHP with MySQL Essential Training
Illustration by Don Barnett

Checking for authorization


From:

PHP with MySQL Essential Training

with Kevin Skoglund

Video: Checking for authorization

In the last movie, we added the ability for users to login. But that's not meaningful until we start requiring that users be logged in, in order to see a page. To go back to our initial ticket metaphor, we don't yet have a doorman or a bouncer checking for hand stamps before we give people access. We need to add enforcement. We need to check for authorization. Let's start by just adding authorization to our admin menu page. So, just the admin menu page is going to require that you be logged in. At the moment, that's not required. We are logged in, we know that because we ran our login successfully, and it knows my user name, and we haven't logged out since then.
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  1. 4m 8s
    1. Welcome
      1m 0s
    2. Using the exercise files
      3m 8s
  2. 15m 6s
    1. What is PHP?
      3m 52s
    2. The history of PHP
      2m 51s
    3. Why choose PHP?
      4m 10s
    4. Installation overview
      4m 13s
  3. 54m 53s
    1. Overview
      2m 33s
    2. Working with Apache Web Server
      6m 56s
    3. Changing the document root
      7m 24s
    4. Enabling PHP
      6m 16s
    5. Upgrading PHP
      3m 30s
    6. Configuring PHP
      10m 3s
    7. Installing MySQL
      5m 46s
    8. Configuring MySQL
      7m 24s
    9. Text editor
      5m 1s
  4. 31m 25s
    1. Overview
      3m 27s
    2. Installing WampServer
      5m 46s
    3. Finding the document root
      2m 24s
    4. Configuring PHP
      8m 12s
    5. Configuring MySQL
      5m 45s
    6. Text editor
      5m 51s
  5. 19m 12s
    1. Embedding PHP code on a page
      6m 43s
    2. Outputting dynamic text
      5m 55s
    3. The operational trail
      2m 27s
    4. Inserting code comments
      4m 7s
  6. 1h 18m
    1. Variables
      7m 50s
    2. Strings
      4m 38s
    3. String functions
      8m 54s
    4. Numbers part one: Integers
      6m 27s
    5. Numbers part two: Floating points
      5m 25s
    6. Arrays
      10m 0s
    7. Associative arrays
      6m 37s
    8. Array functions
      6m 33s
    9. Booleans
      3m 50s
    10. NULL and empty
      5m 15s
    11. Type juggling and casting
      8m 27s
    12. Constants
      4m 43s
  7. 27m 37s
    1. If statements
      6m 0s
    2. Else and elseif statements
      4m 16s
    3. Logical operators
      7m 30s
    4. Switch statements
      9m 51s
  8. 42m 15s
    1. While loops
      8m 41s
    2. For loops
      5m 59s
    3. Foreach loops
      8m 16s
    4. Continue
      8m 28s
    5. Break
      4m 8s
    6. Understanding array pointers
      6m 43s
  9. 37m 25s
    1. Defining functions
      8m 25s
    2. Function arguments
      5m 32s
    3. Returning values from a function
      7m 33s
    4. Multiple return values
      4m 53s
    5. Scope and global variables
      6m 2s
    6. Setting default argument values
      5m 0s
  10. 20m 18s
    1. Common problems
      3m 47s
    2. Warnings and errors
      8m 36s
    3. Debugging and troubleshooting
      7m 55s
  11. 57m 57s
    1. Links and URLs
      5m 33s
    2. Using GET values
      5m 35s
    3. Encoding GET values
      8m 41s
    4. Encoding for HTML
      9m 26s
    5. Including and requiring files
      7m 40s
    6. Modifying headers
      6m 45s
    7. Page redirection
      6m 43s
    8. Output buffering
      7m 34s
  12. 1h 3m
    1. Building forms
      7m 28s
    2. Detecting form submissions
      5m 59s
    3. Single-page form processing
      7m 57s
    4. Validating form values
      10m 40s
    5. Problems with validation logic
      9m 54s
    6. Displaying validation errors
      7m 23s
    7. Custom validation functions
      6m 28s
    8. Single-page form with validations
      7m 25s
  13. 28m 5s
    1. Working with cookies
      2m 49s
    2. Setting cookie values
      5m 55s
    3. Reading cookie values
      6m 1s
    4. Unsetting cookie values
      4m 51s
    5. Working with sessions
      8m 29s
  14. 48m 39s
    1. MySQL introduction
      6m 43s
    2. Creating a database
      7m 41s
    3. Creating a database table
      7m 42s
    4. CRUD in MySQL
      5m 48s
    5. Populating a MySQL database
      7m 32s
    6. Relational database tables
      6m 40s
    7. Populating the relational table
      6m 33s
  15. 56m 4s
    1. Database APIs in PHP
      4m 51s
    2. Connecting to MySQL with PHP
      7m 45s
    3. Retrieving data from MySQL
      8m 47s
    4. Working with retrieved data
      6m 12s
    5. Creating records with PHP
      6m 58s
    6. Updating and deleting records with PHP
      9m 6s
    7. SQL injection
      3m 5s
    8. Escaping strings for MySQL
      6m 45s
    9. Introducing prepared statements
      2m 35s
  16. 35m 58s
    1. Blueprinting the application
      7m 19s
    2. Building the CMS database
      5m 14s
    3. Establishing your work area
      4m 38s
    4. Creating and styling the first page
      4m 22s
    5. Making page assets reusable
      6m 36s
    6. Connecting the application to the database
      7m 49s
  17. 32m 49s
    1. Adding pages to the navigation subjects
      5m 58s
    2. Refactoring the navigation
      6m 7s
    3. Selecting pages from the navigation
      6m 2s
    4. Highlighting the current page
      5m 26s
    5. Moving the navigation to a function
      9m 16s
  18. 1h 45m
    1. Finding a subject in the database
      9m 48s
    2. Refactoring the page selection
      10m 52s
    3. Creating a new subject form
      6m 55s
    4. Processing form values and adding subjects
      11m 20s
    5. Passing data in the session
      9m 16s
    6. Validating form values
      9m 40s
    7. Creating an edit subject form
      8m 30s
    8. Using single-page submission
      7m 44s
    9. Deleting a subject
      9m 44s
    10. Cleaning up
      10m 37s
    11. Assignment: Pages CRUD
      4m 30s
    12. Assignment results: Pages CRUD
      6m 10s
  19. 39m 26s
    1. The public appearance
      8m 52s
    2. Using a context for conditional code
      11m 37s
    3. Adding a default subject behavior
      6m 9s
    4. The public content area
      5m 51s
    5. Protecting page visibility
      6m 57s
  20. 1h 3m
    1. User authentication overview
      4m 3s
    2. Admin CRUD
      8m 41s
    3. Encrypting passwords
      7m 26s
    4. Salting passwords
      5m 42s
    5. Adding password encryption to CMS
      11m 54s
    6. New PHP password functions
      3m 13s
    7. Creating a login system
      11m 28s
    8. Checking for authorization
      5m 48s
    9. Creating a logout page
      5m 40s
  21. 2m 4s
    1. Next steps
      2m 4s

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PHP with MySQL Essential Training
14h 24m Beginner Jun 04, 2013

Viewers: in countries Watching now:

PHP is a popular, reliable programming language at the foundation of many smart, data-driven websites. This comprehensive course from Kevin Skoglund helps developers learn the basics of PHP (including variables, logical expressions, loops, and functions), understand how to connect PHP to a MySQL database, and gain experience developing a complete web application with site navigation, form validation, and a password-protected admin area. Kevin also covers the basic CRUD routines for updating a database, debugging techniques, and usable user interfaces. Along the way, he provides practical advice, offers examples of best practices, and demonstrates refactoring techniques to improve existing code.

Topics include:
  • What is PHP?
  • Installing and configuring PHP and MySQL
  • Exploring data types
  • Controlling code with logical expressions and loops
  • Using PHP's built-in functions
  • Writing custom functions
  • Building dynamic webpages
  • Working with forms and form data
  • Using cookies and sessions to store data
  • Connecting to MySQL with PHP
  • Creating and editing database records
  • Building a content management system
  • Adding user authentication
Subjects:
Developer Servers Programming Languages Web Development
Software:
MySQL PHP
Author:
Kevin Skoglund

Checking for authorization

In the last movie, we added the ability for users to login. But that's not meaningful until we start requiring that users be logged in, in order to see a page. To go back to our initial ticket metaphor, we don't yet have a doorman or a bouncer checking for hand stamps before we give people access. We need to add enforcement. We need to check for authorization. Let's start by just adding authorization to our admin menu page. So, just the admin menu page is going to require that you be logged in. At the moment, that's not required. We are logged in, we know that because we ran our login successfully, and it knows my user name, and we haven't logged out since then.

But what we want to do is add something at the top of this that's going to make sure someone is logged in. So how would we do that? Let's think about that for a moment. Let's go right here before we get to the header. And we have our functions. We have our session loading. So what do we want to do here? We want to write some PHP that is going to check, if not is set. And then check the session. For the admin id. That's it, so if not set, if we haven't set something for that admin id, then they're not logged in.

Now I'm not actually checking to make sure that the id is valid. I'm not making sure that it matches anything. I could do those additional steps and if I wanted more security, I could. Certainly if the user had certain things like if they were only allowed to be logged in until a certain date. Well then I'd have to go to the database probably and look that date up and make sure that it was still accurate. But in this case it's just enough to make sure that it's set. If it is set, then they're allowed to be logged in. But if it's not set, then what we want to do, we want to redirect them to login.php.

So it's that easy. If they're not logged in, redirect them to the login page, otherwise keep going. So, now I'm going to want to put this at the top of every single page where I want this kind of enforcement. So, let's put it in a function so that it makes it easy to do that. I'm just going to cut that and instead, let's just create a function called confirm. Logged in. And that's it. We'll just do confirmed log in up at the top, and after we confirm that they're logged in it'll run the function. The function will either redirect them, or it'll do nothing. Let's go over here to our functions, and after attempt log in, and put our new one.

Function confirm. Logged in. It's not going to take any arguments, because it's going to be looking at the session, so it's going to make sure that the session has them logged in. Now, this would work on its own. There is one other improvement that I want us to make, though. On our site, the pages are either for logged in admins or they're for the non-logged in public, and there's a real distinction between the two. A lot of times, on other websites you're going to build, you're going to have pages that are going to be for both logged in and logged out users. You're just going to want some features to display differently if the person's logged in.

For example, you might just have a simple link up in the header, that says log in if you're not logged in. And then switches to be logged out if you're not logged out. Amazon.com is a good example of this. You can browse the entire Amazon.com website whether you're logged in or not. But the personalization features only happen if you're actually logged in. So, instead of just having this one simple method, let's make another one that's just called logged in. And logged in is just going to take this part right here, I'm going to cut that out and I'm just going to return that, so return, is this yet. And that will then return true or false for logged in, and then I can just take logged in and use that here.

So now, this actually reads better if not logged in, then login. And I also have this function that I can call in those pages, in that dual-context pages. I can say, if logged in, then display this. If not logged in, then don't display it, or display something different. So, it's nice to have these two different functions that I can call. This one is the one that is the enforcement. It makes sure that we're logged in. This one is just a simple check. Are we logged in or not? Alright, let's try it out. Now, let's save our page, close that. Make sure this is saved.

And let's go to admin.php, and reload the page. Now, let me see the page, just fine. That's what we would have expected, 'cuz we were already logged in. So how do we log out? Well, we're going to learn that in the next movie. We're going to create our logout function. For now, though, let's just go to Firefox. And let's just go to our cookies, show cookies, and here's my local host, php session id. Let's just remove that cookie, I basically just killed off my session. I no longer have a link to the session. And now when I reload my admin.php page, voila. Look at that, anytime I try to go to admi.php it takes me to login.

Note that, if we want to log in, there's two ways we could get there. We could either go to login.php and get this page, or we could go to admin.php and get to that page. So, let's try logging in again. Kscogland/g, password, secret. And now, I'm on the page. Now, it lets me in there. Now we want that enforcement on all of the pages that are in the admin area, so I'm going to leave that up to you to add. Just make sure that on every single page, that you also have the session included. It's very important. We need that session every time we're going to have confirmed logged. So make sure you have session.

You have the functions and then you can call confirmed logged in. So just go add that to the top of all your pages. That is all pages in the admin area, except for the login.php. We wouldn't want to protect that. Of course, you don't want to force people to be logged in, in order to see the login page. But all the other pages in the admin area. Will need this confirmed logged in function at the top. And then when you're done, in the next movie we'll create the log out page.

Find answers to the most frequently asked questions about PHP with MySQL Essential Training.


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Q: This course was revised on 6/4/2013. What changed?
A: The old version of this course was 6 years old and it was time for a complete revision, using PHP 5.4. (The tutorials will work with any version of PHP and covers any differences you might encounter). The author has also added updated installation instructions for Mac OS X Mountain Lion and Windows 8. The topics and end project are the same, but the code is slightly different. It also addresses frequently asked questions from the previous version.
 
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