Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Reading cookie values

From: PHP with MySQL Essential Training

Video: Reading cookie values

We now know how to set a cookie using PHP. Next, we need to learn how to use PHP to read back cookie values. As we saw in the first movie of this chapter, PHP takes all cookie values, sent in the request header. And puts them in an associative array, assigned to the super-global $_COOKIE. That's cookie, singular, not plural. Even though this associative array might contain data from several cookies. It's still going to be singular in it's name, don't let that trip you up. And the way that we'll access our values in there is by using our key to get the value from the associative array. Very much like we did when we were working with get and post requests. Let's try it now.

Reading cookie values

We now know how to set a cookie using PHP. Next, we need to learn how to use PHP to read back cookie values. As we saw in the first movie of this chapter, PHP takes all cookie values, sent in the request header. And puts them in an associative array, assigned to the super-global $_COOKIE. That's cookie, singular, not plural. Even though this associative array might contain data from several cookies. It's still going to be singular in it's name, don't let that trip you up. And the way that we'll access our values in there is by using our key to get the value from the associative array. Very much like we did when we were working with get and post requests. Let's try it now.

So, I'm going to start out by working with my existing cookies.php file. I'd already set a cookie here before. If you haven't done that, or if you deleted yours, you'll want to set a new one now. So, go ahead and load this page up in a browser. Reload the page, make sure that you have set that cookie. And then, I'm going to comment it out, so that it's not actually setting it. We're just reading it back, just so that you don't think this has anything to do with what we're about to do down here. And let's just put in pre tags to start and php, print_r, and let's take a peek at cookie.

Let's see what it looks like. We're just going to print out the contents of that associative array. Let's reload that page and you'll see that it brought up that value, test 45. Alright, that's what we had set previously, the test and 45. Now the set, cookie didn't happen here, this is something that was stored. And everytime we reload the page, that gets sent. Every single time, that gets sent to everything that's on local host. Those values are always present with every single request. They're sent with a header of every single request that comes to the web server now.

So, this is just taking a peek at them. I think it's more useful to actually use them. So, let's take these pre tags away. And instead of print cookie, let's change this to actually set the value, test equals cookie. And then, we need the key that we're looking for. So, that is going to be test. That will set the value and then let's just echo it back. Now in truth, you'd probably do something besides just echo it. You might use this as a user ID to look up a user in the database. It's a very common use of it. You might be checking to see someones preference. What language they want to have the site viewed in, or what time zone they're in.

Those kinds of things are good things to store in cookies. Let's comeback and take a look here. Reload the page. And there we go, there's 45. Now, one thing that's very important with cookies is to make sure that they exist before you try and access them. Let's say test2, for example. Let's save that, reload it. See I get an error because it didn't exist. With cookies, first of all, it may not have been set yet. You can't assume that anyone came to your site through any certain path, necessarily. Meaning if there's a log in page, maybe they cant get to anything past the log in page without logging in. You don't know for sure if they went to your home page first or if they came in through some directory link deeper into your website. And also, users can delete cookies, we saw that, we were able to delete cookies by going to our preferences.

So, a user could delete their cookies and then they don't have it anymore. And your site would return an error if you didn't check to see whether it was there or not. We know how to do that checking. We can just do it with if is set and then I'll just copy this rather than type it again. So if that's set, then we'll set it. Else, we'll do test equals, and we'll just make it equal to an empty string. So, let's try that now. Come back and reload it, 45. Same thing if we were to check and see if it is test2, which doesn't exist anymore. Now my page doesn't blow up.

So, it's a little friendlier. This is another place where that ternary operator that we talked about is really convenient. Instead of writing this whole big block of code that takes up five different lines, instead we can do it to one line. We could have test. And then, let me just grab some of these pieces here, isset, question mark. And if it is set, this is the true value. If it's not set, this is the false value. You can see that's a nice way to condense all that down to one simple line, test. If it's set, here's the value. If it's not, here's the other value. We need a semicolon at the end. And I'll just reload the page.

There we go, 45. So, that's really all there is to pulling back these cookie values and accessing them from cookie. However, there's one more important thing that I want you to take a peek at. Let's uncomment this set cookie, and let's now set the cookie for test. And let's make it equal to, let's say something really obviously different, 1,2,3. All right, so we'll save it. Let's come back here and let's reload our page. So, the first thing that's going to happen is it executes the code, it's going to come down and do set cookie, right? And then, it will keep going down and show us the cookie.

Right, ready? Reload. Wait a minute, it still says 45. Reload again. Now it says 123. Let's try again. Let's set it this time to be equal to a string. We'll make it, hello, save it, come back, reload the page, still 123. Reload the page again, now we get hello. Do you understand why that's happening? It's because this cookies super global are the values that are coming in from the request. It has nothing to do with what we set in the cookie here. This is instructing what's going to be in our response headers. It's telling PHP, when you construct the response, here's the cookie that you need to send back with that response.

The two are not connected. So, this is the values that came in from the user, these are the values that are going out to the user. But they're not the same and it doesn't do any kind of syncing between them. So, don't let that trip you up. You set cookie to some different value let's say that you had a, a last login time or something. So, you do set cookie well don't think that you can find that value that you just set inside this super global. This is going to be an old outdated value now. This new value won't be in play really, until that response is back to the user's browser and actually gets set as a cookie.

And then, from then on, every future request then it will be inside our super global for cookie. Cookie holds the values from the previous request. It's not changed when you set the cookie.

Show transcript

This video is part of

Image for PHP with MySQL Essential Training
PHP with MySQL Essential Training

131 video lessons · 32694 viewers

Kevin Skoglund
Author

 
Expand all | Collapse all
  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

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed PHP with MySQL Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.