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Processing form values and adding subjects

From: PHP with MySQL Essential Training

Video: Processing form values and adding subjects

In the last movie, we created a new subject form. That's just an HTML form and it's going to submit to create subject.php. Create subject.php is going to do the form processing. That's what we're going to work on in this movie, is how we process that form. Now what I have in mind for that page is that it won't render any HTML whatsoever. No matter what happens, there will be no HTML, it's PHP only. And at the end it will redirect the user to an appropriate HTML page. So on success, it will redirect them to one place.

Processing form values and adding subjects

In the last movie, we created a new subject form. That's just an HTML form and it's going to submit to create subject.php. Create subject.php is going to do the form processing. That's what we're going to work on in this movie, is how we process that form. Now what I have in mind for that page is that it won't render any HTML whatsoever. No matter what happens, there will be no HTML, it's PHP only. And at the end it will redirect the user to an appropriate HTML page. So on success, it will redirect them to one place.

On failure it will redirect them somewhere else. Let's try that. So, because we know we're going to be redirecting, let's go ahead and open up functions.php. And let's paste in that redirect to function that we wrote in the earlier chapters. So, redirect to new location, we'll use a header request to set the location and do a redirect. And then exit afterwards. Remember all the things we talked about with headers. We can't send any white space before we make this call or else we have to have output buffering turned on. My output buffering is turned on.

I'll close it up. Let's open up newsubject.php. And let's also open up a new empty file. This is going to be our create subject page. Let's go ahead and do save, create subject.php. It's going to be inside widget corp inside public. That's where we're going to save it. Alright so create subject. That's the page that we're submitting to, we can confirm that right here. Create subject.php. So, this will post that information over here. So, what information do we need on this create_subject page to be able to do form processing? We don't need any of this HTML that we were working with before.

We don't need to even find the selected page or to bring up the header. We do want these. These are going to be the first thing we want, our database connection and our functions. Now, we don't want the footer down here at the bottom. If you remember our footer actually had a little bit of PHP in it, and we do want to get that. So, we go to our footer file, we have this closing the database connection at the end, we're just going to go ahead and be good citizens and have that the end. I'm going to clean this up a little bit, make it smaller, so now it all just fits on a couple of lines.

Okay, so we've now got our database connection, we've got our functions to find, and we're closing the database connection at the end. What we want to do now is process the form. We can cheat by looking back a little bit at what we did when we were working in the sandbox. Let's open our sites folder and sites, sandbox. In particular databases insert, let's open that up, that's where we did some inserting and look at this. We actually did an insert into objects, so that's going to give us our query that we need, and then I also want to look down here at form processing. Form processing.php.

Now notice that the way we detected the form submission, remember this? If is set post submit. So let's grab that. We're going to want that. We're going to check to see whether or not the post has been submitted. And if it has, then we'll do our form processing. If it's not, then we'll do something else. Now remember, this is based on having submit sent with the form. How do we do that. Let's look over here in our sandbox at the form to remind ourselves, input type submit name equals submit.

That's the magic one right there. This is the value is what the button is going to say. Name equals submit is the value that will submitted with the form request. If we don't have that, it submits nothing so its very important. I'm going to copy that. I'm just going to come back over here. And let's look at the form that we had, in Widget Corp for new subject.php. It does not have that, it has the type and it has the value. We need it to also have the name. So super important, name equals submit. We'll save that.

Now it will trigger this action. It'll say okay, this was a post request. And even more than that, it was a post request from the form that has a submit value that got submitted. Now, if we don't get that, that means it probably was a get request. It means that someone went to their web browser and typed in create subject.php and hit Return without submitting a form. We don't want to allow that so if that happens, we're going to say redirect to, and we'll just go back to new subject.php.

This is probably a get request. I'll just make a little note there and so we'll redirect them. Let's try that real quick just to see how that works. We'll go to firefox, here's our new subject page, but let's instead, let's just do a get request by typing create subject.php. We got redirected to new subject. Now if you didn't get redirected, if you got an error instead, it might be because of that white space issue with doing redirects in the header. Go back and review that section and either fix the white space problem, or it may be easier to turn on output buffering.

Alright let's jump back over to our code again, and let's steal all of this that we did here for databases insert. All if it down here, the whole thing. I'm going to copy all that and I'm going to paste it over here. Because that's going to be my form processing. If it's submitted, then process the form. How do we do that? Well, here's the steps. We get our values. Now, we hard coded those before. Then said they normally come from the post request, well now they are going to come from the post.

So, from our super global post, we can ask it for menu name, and we can do the same thing for position and visible. I'm also using typecasting still on these to make sure that position gets turned into an integer. For visible I can turn into an integer or you can turn into a Boolean. Either one is fine, it doesn't matter because what we are going to be submitting to MySQL. In both cases is going to be translated by MySQL, rather type cast by MySQL into a Boolean, so I'm going to leave it just as a simple integer. It'll be zero or one, that's what we are expecting to get back. I've got my mysql real escape string.

We still want that to prevent sql injection, don't need my message about that anymore. We know what we're doing. Don't need that one either. Insert into subjects. These are the three fields we're going to be inserting, so that's all still good. And then we have our MySQL query. That's still fine. If we get a result back, then it's success. Instead of echoing success, though, now, we're going to redirect to. And let's redirect back to, manage content.php, on failure, instead of doing a die, let's also redirect back, in that case, too.

Redirect to, and we'll go back to new subject also. Now it's worth mentioning that a failure here is a pretty catastrophic failure. It means something really went wrong. Because it's not about validations. We're not doing any kind of validating of the data yet. We'll get to that in a minute. We're submitting values to MySQL and MySQL is rejecting them. It's saying for example, that the position couldn't be inserted. And therefore it won't do the insert. Now it's certainly possible to violate the data rules that MySQL has, that we set up. For example, if you told position that it's an integer of type 3. Well then we can only put in positions up to 999. Soon as we try to put in 1000, it's going to reject it. So I just want to be clear about when that would happen. So, before we try this out and submit it, there's one other improvement that I want us to make.

This MySQL real escape string, it's kind of a long function name to have to remember and recall. And you have to remember to provide the connection before you do it. I think we can come up with something that's a little more convenient than that. So, I'm going to open up functions.php. And right after redirect, I'm going to make a new function here. And I'm just going to call it MySQL_prep. You can call it anything you'd like. But the idea here is that, whatever preparation we need for submitting to MySQL, this function will take care of. We'll pass in a string, that's what it's going to expect is a string.

And instead of having this here, we'll put it in here, and instead, we're going to escape this string. We're going to set, though, escaped string. It's going to be what it becomes. And, afterwards we will do return of escaped string. Notice that we have our connection here, so we need to make sure that we have that available to us. We'll bring that in from the global scope. And now, mysql_ prep will do the exact same thing for us.

It'll take care of this business for us. There are a couple advantages. One, if the process of preparing things for MySQL ever changes, then we can just change things in mysql_prep function. For example, if I was using the MySQL adapter, and I wanted to switch to the MySQLi adapter, I'd just change it in one place. All the places in my code where I was doing my preparation, they can stay the same. The other thing, and the main reason I like this, is because now we can come back over here and we can just use mysql_prep and just pass in the string.

Much shorter, much cleaner, still clear what we're trying to do and it just hides all of the mechanics of it away from us. What's also nice, is that I think now instead of having this as a separate line, it's short enough and simple enough, you can just put it up here. When we first bring that value in we'll prepare it for MySQL. So, now it's escaped by the time it's set to menu name and so we're free to use it here inside our query. Okay, so let's try this out. How are we going know if we succeed or if we fail? We're going to know based on whether it redirects to manage content or back to new subject.

That's what going to be our indication. We could say message equals subject creation failed, that's not bad. Let's do the same thing here. Message equals subject created, that'll work. Put a period at the end of both of those. Those would be a nice message to display. However, there's nowhere to display it, we're redirecting. The redirect is a new request, it's a new part of the request response cycle. Remember that, when we talked about redirects? So, this would have to be stored somewhere. We'll look at that in the next movie. For now, let's just test it out and look based on the page that it results in for whether or not it works.

So we'll go back to Firefox. We're on our new subject page, I'll just reload that just to make sure we're still there. Menu name. Let's put in a sample subject. The position, I'm going to put it in as position five. And visible, I'll say yes. Now, note if you did put it in as a different position here, two, three or four, we don't have a mechanism that will reorder the other ones. That's a, a feature, an enhancement you can add later. For right now, the position would just be a duplicate if we put it in as position two we would have two things that had position two. So, we're going to put it in as position five.

So, let's say sample subject, visible yes. Create subject and there we are. We're on our managed content page and it worked and we know that it worked also because here it is. Sample subject, we can see it. It's right here. Now the idea of looking to see what page you are on, to know if you succeeded or not is not great user feedback. It'd be much better if we could have a message like the ones that we had here. Message equals subject created and to be able to display that to the user. To do that we'll have to use what we know about sessions, and we'll look at that in our next movie.

Show transcript

This video is part of

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

131 video lessons · 38120 viewers

Kevin Skoglund
Author

 
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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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