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PHP with MySQL Essential Training
Illustration by Don Barnett

Page redirection


From:

PHP with MySQL Essential Training

with Kevin Skoglund

Video: Page redirection

Alright. So in the last movie we took a small detour so that we could understand what headers are and how they work. During that detour, hopefully I impressed upon you the importance of altering headers before even a blank space is output to the browser. Now, we're ready to talk about when you'll need to work with the headers most often, and that's when we want to do Page Redirection. That's where they're really useful. So what is page redirection, and why do we need it? Well, let's say that the user goes to a log in page, they submit their log in information on a web form, gets sent to a PHP page for processing. If they succeed in logging in, we want to send them to one page. If they fail, we want to send them to another page. That's where redirection comes in, being able to send them to another page. A page that's different from the one that they requested, or even the one that the form submitted to.
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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

Page redirection

Alright. So in the last movie we took a small detour so that we could understand what headers are and how they work. During that detour, hopefully I impressed upon you the importance of altering headers before even a blank space is output to the browser. Now, we're ready to talk about when you'll need to work with the headers most often, and that's when we want to do Page Redirection. That's where they're really useful. So what is page redirection, and why do we need it? Well, let's say that the user goes to a log in page, they submit their log in information on a web form, gets sent to a PHP page for processing. If they succeed in logging in, we want to send them to one page. If they fail, we want to send them to another page. That's where redirection comes in, being able to send them to another page. A page that's different from the one that they requested, or even the one that the form submitted to.

I'm sure you've seen this in e-commerce. You submit your order, and then after a brief pause, you suddenly are redirected to another page. Your browser suddenly ends up with a different URL at the end, that says something about your receipt, has your order number or something like that in it. When that happens, you've been redirected. In HTTP, the standard that the web uses, we can redirect the browser to a new URL by using a 302 redirect. It has two parts: a status code of 302 found and a location attribute that indicates the new URL.

We saw in the last movie how we can change the header. Well, PHP is smart enough to know that if we're setting the location in the header, then we also want to set the status code to 302 at the same time. We don't have to manually set it and make a two-header request, we can just do it with one. It's really nice. Now, notice "Location" colon space, and the capital "L" in location. It has to be exactly like that, or it won't work. Capital L "Location" colon space and then the new URL. A 302 status code in the header when it's received by the browser, tells the browser that it should immediately make a new, second get request to the new location.

It ignores any page data that follows the header, in fact it expects that there won't be anything else. The re-request happens very fast in the background, so the user doesn't even know it's happened. But it actually is a second get request that takes place. Let's try it. So, let's try to open up basic.html and let's do Save As on it, and we're going to call this redirect.php. So, let's put it at the top here, remember we already know that it has to go at the very top, no space at all. We'll open our PHP tags, and this is how you redirect to a new page. Header, open our parenthesis, open our quotes, capital L "Location" colon space and then the page that you want it to go to.

I'm just going to use basic.html. That's going to redirect to basic.html. Now, this can be a relative path to the file, which is what I'm doing here. I'm saying it's basically in the same directory, or I could provide everything. I could say, this should go to http:www.lynda.com, put a full URL there. Now, if we try this as it is, what'll happen? Well, the redirect will be sent here, but there's also data that's being sent afterwards. And we don't really want to send any data after that. So, the last step is that you always want to do exit afterwards. So, exit is going to tell it, we're done. The script is over, the PHP script is finished now, we've done the redirect. That's it.

And that's because we don't need anything else. Once we've done a redirect, that's it. That's the whole response that's going to be sent back. So let's try it. And we should change then this to Redirect, just for completeness. And let's go back to Firefox, and let's just try redirect.php. And there we are. It redirected, notice now the URL is basic.html. That's where it went to, untitled is the title of that page. And if we do web developer view source, then we'll that there's the content of the basic.html page. So it did send me immediately to it again.

If you want to just try it a few times, you can watch it happen. Redirect.php, and there it is, it happens very, very quickly, especially since we're on the same machine, not even reaching out across the internet. But even then, it happens very fast. It's not, the speed of making a second request to something you really don't have to worry about. Now, instead of trying to remember the, the syntax here for remembering that you have to call header, you have to put location and it has to be exactly like this, that you have to call exit, I find it really helpful to wrap all of this up into a function. So, let's create a function for ourselves.

Function, and we'll call it redirect_to, and it's going to take as an argument new location. And then we'll open our curly braces there, I'll just indent all of this, it looks nice. And then of course instead of putting basic.html here, it's going to just append new location. Now, we can just call redirect to and that will do the redirect for us. Just try here, redirect_to. And let's go ahead and just give it basic.html.

Here we are. Come back here. Redirect.php, basic.html. And send us back there. I find this really helpful. I find this much easier to use, and user-friendly than trying to remember that I have to do things like add exit after. So let's just use this in some PHP. So let's say that we're going to a value for logged in, and that's going to be equal to get, and we'll say logged in. So the value of get logged in is what will become logged in, and then let's do a simple if statement. If $logged_in is equal to 1, then we'll do one thing, otherwise, we'll redirect somewhere else.

If they are logged in, we're going to let them see basic.html. If they are not logged in, let's redirect them to somewhere else, like lynda.com. So you can see what it looks like when you go to a different URL completely, that works just as well. Save it. Alright. So I definitely have to send a value for logged_in here. I'm not doing any kind of default value, so let's make sure that I send that. Redirect.php logged in equals 1. There it is, sent me to basic.html. Let's try again. Redirect.php and logged in equals zero. Really anything would work.

And you see that it brings me up to the lynda.com page. So that's it. You need to know this syntax, which I think you can roll up into a nice easy to use function. And that you can't put any space before it. If I try something like this, then even if I am logged in, redirect.php logged in equals 1. I still get that warning, cannot modify header information, because something has already been sent. Even though it's just a line return, something has been sent before the headers. The only way that we can get around that is by using output buffering, and that's what we'll talk about in the next movie.

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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