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PHP with MySQL Essential Training
Illustration by Don Barnett

Single-page form processing


From:

PHP with MySQL Essential Training

with Kevin Skoglund

Video: Single-page form processing

In the last movie, we learned how to detect if a form was being submitted to a page or whether the page was being loaded directly. We first learned it in order to keep our page from blowing up on us if our values weren't in the post array. However, there's another way that we can use it that's super-handy. It will allow us to have a single page that contains both the form and the form processing. We'll essentially have a form that submits to itself. Now there's nothing wrong with having the form and the processing on two separate pages. I'm not trying to tell you that one is better than the other. But having them on one page does add a few nice perks.
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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

Single-page form processing

In the last movie, we learned how to detect if a form was being submitted to a page or whether the page was being loaded directly. We first learned it in order to keep our page from blowing up on us if our values weren't in the post array. However, there's another way that we can use it that's super-handy. It will allow us to have a single page that contains both the form and the form processing. We'll essentially have a form that submits to itself. Now there's nothing wrong with having the form and the processing on two separate pages. I'm not trying to tell you that one is better than the other. But having them on one page does add a few nice perks.

All the logic related to the form, then, is in one file. So, if you have a form that is for logging in, we have both the login html code that is for displaying the form. And the processing of it, all in a single file maybe called login.php. It also makes it very easy then to redisplay the form if there are errors, because if there are errors we just let the page keep processing. And guess what's further down the page? The form. It also makes it easy then to return error messages to that form, that's going to show up a little later.

And to populate those fields with previous values. So, let's say that you were asked to enter a country name. And the country value that you entered was not a valid country. Well we could redisplay the form and include the value you had before. So, that you could make a correction to it and resubmit it again. Now a single page form is not the only way to get these benefits. Especially the last three. You also know how to use include, to pull in a common form file for both pages that would also work. But I do want you to see this technique. I do want you to see how it works because this way of doing it can also be useful instead of just doing it by using include.

So, we already had our form, and our form processing pages. I just want to take these and resave them as a few file. So, I'm going to go to form.php and I'll use Save As on this, and we'll call this formsingle.php, we'll save it. Now instead of going to form processing we know it's going to submit to form single. So, it's going to submit to itself. Now once it gets there it needs to do some processing, so let's go to our form processing and let's steal some of the bits that we had here. What I mainly want to get is this line here that checks to see whether or not the submission took place.

And I'm going to put it before we even get up to the !doctype. Put all the way up here at the top inside some php tags there we go. So, if it has been submitted form was submitted that's what that tells us, if not we will go ahead and put an else here well do whatever happens if it's not submitted. So what do we want to do? If the form was submitted, then we want to set username equal to post and username. And we'll do the same thing for password. Password.

And for now, let's just go ahead and have it also output a message, we'll set message equal to logging in. And then we'll put the user name. So, this is a just placeholder, just so that we can see something come back to us when we're doing this. Of course we're not actually trying to login. We're not accessing a database or anything like that. We're just going to have it display I'm trying to log them in. And we'll just leave it at that. Now if it's not submitted, then let's have an alternative message. And that one's going to be please log in.

Nice and simple so now we have a message that occurs one time or not the other time. Let's drop down here into the form and let's just echo that message right above the form. We'll put our PHP tags echo the message and we'll put a br tag at the end. So, let's just try that let's bring that up and see what we get. And instead of form processing, let's load form single. So, there it is, I get please log in and now I"m going to try to log in... kevinskoglund, password password, and there it is. Logging in kevinskoglund. Now you can see that the two actions, the two possibilities for this page, one is if the form was submitted.

And one is if it's not, and in both cases it's going to redisplay the form to us right now. We'll take care of that in just a minute. Now we also could put in default values here. So, the username you notice when it came back and said logging in, it didn't give me the user name again. But what if this had been an error? Let's just do that, instead of logging in let's have it say, there were some errors. Now of course there aren't errors. We'll just reload the page this way. It'll ask me if I want to resubmit it with the post data. That's what it's asking me for. And then it comes back and says there were some errors. All right, so now let's imagine that there are errors. Well, we would want it to redisplay the username to us. Echo, make sure you use echo username, there we go. It's going to echo the username, but let's be careful here. We have now the condition where username is set if it was posted, but if it wasn't, this isn't going to have a value.

So, our form won't work in this case unless we provide the default value here. So, now we have a default value. Let's come back, we'll reload the page by hitting the Return key in the URL, and we get please log in. Kevin and Submit. There were some errors and it repopulated my username here with Kevin. Now, because that's something that the user is submitting, we want to make sure that we're careful about that and use HTML special chars on it. We learned about that. Put my semicolon at the end. So, that will make sure that no matter what the user typed in there, maybe they typed in a name that had a less than sign in it, it's still not going to break it. It comes back just fine.

The message here, we don't need to worry about putting HTML special chars on because we have control of that message. It's not something that the user would have submitted. Now the moment that we start putting user data in there, or database data in there. Then we'll want to also make sure we escape that, but for now I know what that message is going to be. It's going to be one of two things so I don't really need to be worried about it. So, let's also try incorporating a redirect. We saw how to do redirects earlier. I could add the redirect function to the top of this page but I'm actually going to do it the proper way. And I'm going to go over here to included functions that I was working with before.

And I'm just going to add a new function. Don't worry about, hello, that's fine. But I'm going to add that redirect to function from here, and this file then, can hold my functions. And then, I'll come back over here and I'll use require once on included functions.php. And now I can use that redirect too. The form was submitted. Let's put in a conditional that checks to see whether or not we've successfully logged in. Now we're not, don't have a database set up or anything, but let's just do a real simple one. Let's say the user name is equal to Kevin and the password is equal to Secret, then we'll have a successful login. Successful login.

If not, well, then there were some errors. Take this and paste it up here. I actually don't need password, because I'm not re-displaying the password to the user. But I do want to have username set, so that I get that nice value dropped back in my form. So a successful login now will redirect to. And let's just have it go to basic.html. So let's try it. Come back into my form, load it up. Please log in. I'll put in Kevin S, to begin with, with password of secret. That's not going to work. Oh, undefined variable user name, alright.

So I have a problem here. Let's go and take a look, at line seven. User name is not set. ha. I need to move this, up above. And I do need to add my password back in again. Password, password. Okay. So now, those will be set, and then I can check those values. Let's try it one more time. There's the form. Kevin S. Secret. Submit, there were some errors. My name re-displayed. let me fix that. It's kevin, secret, make sure I type it right, Submit and I got redirected to basic.html.

You're sure to see how this all comes together, how we're able to have different conditionals, the redirects, the default values, a form. All of this happens and we're doing it all on a single page. Now that we have some comfort working with forms, in the next movie I want to talk about how to validate form data.

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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