Form Validation
CodeIgniter provides a comprehensive form validation and data prepping class that helps minimize the amount of code you'll write.
- Overview
- Form Validation Tutorial
- The Form
- The Success Page
- The Controller
- Setting Validation Rules
- Setting Validation Rules Using an Array
- Cascading Rules
- Prepping Data
- Re-populating the Form
- Callbacks
- Setting Error Messages
- Changing the Error Delimiters
- Translating Field Names
- Showing Errors Individually
- Saving Sets of Validation Rules to a Config File
- Using Arrays as Field Names
- Rule Reference
- Prepping Reference
- Function Reference
- Helper Reference
Overview
Before explaining CodeIgniter's approach to data validation, let's describe the ideal scenario:
- A form is displayed.
- You fill it in and submit it.
- If you submitted something invalid, or perhaps missed a required item, the form is redisplayed containing your data along with an error message describing the problem.
- This process continues until you have submitted a valid form.
On the receiving end, the script must:
- Check for required data.
- Verify that the data is of the correct type, and meets the correct criteria. For example, if a username is submitted it must be validated to contain only permitted characters. It must be of a minimum length, and not exceed a maximum length. The username can't be someone else's existing username, or perhaps even a reserved word. Etc.
- Sanitize the data for security.
- Pre-format the data if needed (Does the data need to be trimmed? HTML encoded? Etc.)
- Prep the data for insertion in the database.
Although there is nothing terribly complex about the above process, it usually requires a significant amount of code, and to display error messages, various control structures are usually placed within the form HTML. Form validation, while simple to create, is generally very messy and tedious to implement.
Form Validation Tutorial
What follows is a "hands on" tutorial for implementing CodeIgniters Form Validation.
In order to implement form validation you'll need three things:
- A View file containing a form.
- A View file containing a "success" message to be displayed upon successful submission.
- A controller function to receive and process the submitted data.
Let's create those three things, using a member sign-up form as the example.
The Form
Using a text editor, create a form called myform.php. In it, place this code and save it to your applications/views/ folder:
The Success Page
Using a text editor, create a form called formsuccess.php. In it, place this code and save it to your applications/views/ folder:
The Controller
Using a text editor, create a controller called form.php. In it, place this code and save it to your applications/controllers/ folder:
Try it!
To try your form, visit your site using a URL similar to this one:
example.com/index.php/form/
If you submit the form you should simply see the form reload. That's because you haven't set up any validation rules yet.
Since you haven't told the Form Validation class to validate anything yet, it returns FALSE (boolean false) by default. The run() function only returns TRUE if it has successfully applied your rules without any of them failing.
Explanation
You'll notice several things about the above pages:
The form (myform.php) is a standard web form with a couple exceptions:
- It uses a form helper to create the form opening. Technically, this isn't necessary. You could create the form using standard HTML. However, the benefit of using the helper is that it generates the action URL for you, based on the URL in your config file. This makes your application more portable in the event your URLs change.
- At the top of the form you'll notice the following function call:
<?php echo validation_errors(); ?>This function will return any error messages sent back by the validator. If there are no messages it returns an empty string.
The controller (form.php) has one function: index(). This function initializes the validation class and loads the form helper and URL helper used by your view files. It also runs the validation routine. Based on whether the validation was successful it either presents the form or the success page.
Setting Validation Rules
CodeIgniter lets you set as many validation rules as you need for a given field, cascading them in order, and it even lets you prep and pre-process the field data at the same time. To set validation rules you will use the set_rules() function:
$this->form_validation->set_rules();
The above function takes three parameters as input:
- The field name - the exact name you've given the form field.
- A "human" name for this field, which will be inserted into the error message. For example, if your field is named "user" you might give it a human name of "Username". Note: If you would like the field name to be stored in a language file, please see Translating Field Names.
- The validation rules for this form field.
Here is an example. In your controller (form.php), add this code just below the validation initialization function:
$this->form_validation->set_rules('username', 'Username', 'required');
$this->form_validation->set_rules('password', 'Password', 'required');
$this->form_validation->set_rules('passconf', 'Password Confirmation', 'required');
$this->form_validation->set_rules('email', 'Email', 'required');
Your controller should now look like this:
Now submit the form with the fields blank and you should see the error messages. If you submit the form with all the fields populated you'll see your success page.
Note: The form fields are not yet being re-populated with the data when there is an error. We'll get to that shortly.
Setting Rules Using an Array
Before moving on it should be noted that the rule setting function can be passed an array if you prefer to set all your rules in one action. If you use this approach you must name your array keys as indicated:
$config = array(
array(
'field' => 'username',
'label' => 'Username',
'rules' => 'required'
),
array(
'field' => 'password',
'label' => 'Password',
'rules' => 'required'
),
array(
'field' => 'passconf',
'label' => 'Password Confirmation',
'rules' => 'required'
),
array(
'field' => 'email',
'label' => 'Email',
'rules' => 'required'
)
);
$this->form_validation->set_rules($config);
Cascading Rules
CodeIgniter lets you pipe multiple rules together. Let's try it. Change your rules in the third parameter of rule setting function, like this:
$this->form_validation->set_rules('username', 'Username', 'required|min_length[5]|max_length[12]');
$this->form_validation->set_rules('password', 'Password', 'required|matches[passconf]');
$this->form_validation->set_rules('passconf', 'Password Confirmation', 'required');
$this->form_validation->set_rules('email', 'Email', 'required|valid_email');
The above code sets the following rules:
- The username field be no shorter than 5 characters and no longer than 12.
- The password field must match the password confirmation field.
- The email field must contain a valid email address.
Give it a try! Submit your form without the proper data and you'll see new error messages that correspond to your new rules. There are numerous rules available which you can read about in the validation reference.
Prepping Data
In addition to the validation functions like the ones we used above, you can also prep your data in various ways. For example, you can set up rules like this:
$this->form_validation->set_rules('username', 'Username', 'trim|required|min_length[5]|max_length[12]|xss_clean');
$this->form_validation->set_rules('password', 'Password', 'trim|required|matches[passconf]|md5');
$this->form_validation->set_rules('passconf', 'Password Confirmation', 'trim|required');
$this->form_validation->set_rules('email', 'Email', 'trim|required|valid_email');
In the above example, we are "trimming" the fields, converting the password to MD5, and running the username through the "xss_clean" function, which removes malicious data.
Any native PHP function that accepts one parameter can be used as a rule, like htmlspecialchars, trim, MD5, etc.
Note: You will generally want to use the prepping functions after the validation rules so if there is an error, the original data will be shown in the form.
Re-populating the form
Thus far we have only been dealing with errors. It's time to repopulate the form field with the submitted data. CodeIgniter offers several helper functions that permit you to do this. The one you will use most commonly is:
set_value('field name')
Open your myform.php view file and update the value in each field using the set_value() function:
Don't forget to include each field name in the set_value() functions!
Now reload your page and submit the form so that it triggers an error. Your form fields should now be re-populated
Note: The Function Reference section below contains functions that permit you to re-populate <select> menus, radio buttons, and checkboxes.
Important Note: If you use an array as the name of a form field, you must supply it as an array to the function. Example:
<input type="text" name="colors[]" value="<?php echo set_value('colors[]'); ?>" size="50" />
For more info please see the Using Arrays as Field Names section below.
Callbacks: Your own Validation Functions
The validation system supports callbacks to your own validation functions. This permits you to extend the validation class to meet your needs. For example, if you need to run a database query to see if the user is choosing a unique username, you can create a callback function that does that. Let's create a example of this.
In your controller, change the "username" rule to this:
$this->form_validation->set_rules('username', 'Username', 'callback_username_check');
Then add a new function called username_check to your controller. Here's how your controller should now look:
Reload your form and submit it with the word "test" as the username. You can see that the form field data was passed to your callback function for you to process.
To invoke a callback just put the function name in a rule, with "callback_" as the rule prefix.
You can also process the form data that is passed to your callback and return it. If your callback returns anything other than a boolean TRUE/FALSE it is assumed that the data is your newly processed form data.
Setting Error Messages
All of the native error messages are located in the following language file: language/english/form_validation_lang.php
To set your own custom message you can either edit that file, or use the following function:
$this->form_validation->set_message('rule', 'Error Message');
Where rule corresponds to the name of a particular rule, and Error Message is the text you would like displayed.
If you include %s in your error string, it will be replaced with the "human" name you used for your field when you set your rules.
In the "callback" example above, the error message was set by passing the name of the function:
$this->form_validation->set_message('username_check')
You can also override any error message found in the language file. For example, to change the message for the "required" rule you will do this:
$this->form_validation->set_message('required', 'Your custom message here');
Translating Field Names
If you would like to store the "human" name you passed to the set_rules() function in a language file, and therefore make the name able to be translated, here's how:
First, prefix your "human" name with lang:, as in this example:
$this->form_validation->set_rules('first_name', 'lang:first_name', 'required');
Then, store the name in one of your language file arrays (without the prefix):
$lang['first_name'] = 'First Name';
Note: If you store your array item in a language file that is not loaded automatically by CI, you'll need to remember to load it in your controller using:
$this->lang->load('file_name');
See the Language Class page for more info regarding language files.
Changing the Error Delimiters
By default, the Form Validation class adds a paragraph tag (<p>) around each error message shown. You can either change these delimiters globally or individually.
- Changing delimiters Globally
To globally change the error delimiters, in your controller function, just after loading the Form Validation class, add this:
$this->form_validation->set_error_delimiters('<div class="error">', '</div>');In this example, we've switched to using div tags.
- Changing delimiters Individually
Each of the two error generating functions shown in this tutorial can be supplied their own delimiters as follows:
<?php echo form_error('field name', '<div class="error">', '</div>'); ?>Or:
<?php echo validation_errors('<div class="error">', '</div>'); ?>
Showing Errors Individually
If you prefer to show an error message next to each form field, rather than as a list, you can use the form_error() function.
Try it! Change your form so that it looks like this:
If there are no errors, nothing will be shown. If there is an error, the message will appear.
Important Note: If you use an array as the name of a form field, you must supply it as an array to the function. Example:
<?php echo form_error('options[size]'); ?>
<input type="text" name="options[size]" value="<?php echo set_value("options[size]"); ?>" size="50" />
For more info please see the Using Arrays as Field Names section below.
Saving Sets of Validation Rules to a Config File
A nice feature of the Form Validation class is that it permits you to store all your validation rules for your entire application in a config file. You can organize these rules into "groups". These groups can either be loaded automatically when a matching controller/function is called, or you can manually call each set as needed.
How to save your rules
To store your validation rules, simply create a file named form_validation.php in your application/config/ folder. In that file you will place an array named $config with your rules. As shown earlier, the validation array will have this prototype:
$config = array(
array(
'field' => 'username',
'label' => 'Username',
'rules' => 'required'
),
array(
'field' => 'password',
'label' => 'Password',
'rules' => 'required'
),
array(
'field' => 'passconf',
'label' => 'Password Confirmation',
'rules' => 'required'
),
array(
'field' => 'email',
'label' => 'Email',
'rules' => 'required'
)
);
Your validation rule file will be loaded automatically and used when you call the run() function.
Please note that you MUST name your array $config.
Creating Sets of Rules
In order to organize your rules into "sets" requires that you place them into "sub arrays". Consider the following example, showing two sets of rules. We've arbitrarily called these two rules "signup" and "email". You can name your rules anything you want:
$config = array(
'signup' => array(
array(
'field' => 'username',
'label' => 'Username',
'rules' => 'required'
),
array(
'field' => 'password',
'label' => 'Password',
'rules' => 'required'
),
array(
'field' => 'passconf',
'label' => 'PasswordConfirmation',
'rules' => 'required'
),
array(
'field' => 'email',
'label' => 'Email',
'rules' => 'required'
)
),
'email' => array(
array(
'field' => 'emailaddress',
'label' => 'EmailAddress',
'rules' => 'required|valid_email'
),
array(
'field' => 'name',
'label' => 'Name',
'rules' => 'required|alpha'
),
array(
'field' => 'title',
'label' => 'Title',
'rules' => 'required'
),
array(
'field' => 'message',
'label' => 'MessageBody',
'rules' => 'required'
)
)
);
Calling a Specific Rule Group
In order to call a specific group you will pass its name to the run() function. For example, to call the signup rule you will do this:
if ($this->form_validation->run('signup') == FALSE)
{
$this->load->view('myform');
}
else
{
$this->load->view('formsuccess');
}
Associating a Controller Function with a Rule Group
An alternate (and more automatic) method of calling a rule group is to name it according to the controller class/function you intend to use it with. For example, let's say you have a controller named Member and a function named signup. Here's what your class might look like:
<?php
class Member extends Controller {
function signup()
{
$this->load->library('form_validation');
if ($this->form_validation->run() == FALSE)
{
$this->load->view('myform');
}
else
{
$this->load->view('formsuccess');
}
}
}
?>
In your validation config file, you will name your rule group member/signup:
$config = array(
'member/signup' => array(
array(
'field' => 'username',
'label' => 'Username',
'rules' => 'required'
),
array(
'field' => 'password',
'label' => 'Password',
'rules' => 'required'
),
array(
'field' => 'passconf',
'label' => 'PasswordConfirmation',
'rules' => 'required'
),
array(
'field' => 'email',
'label' => 'Email',
'rules' => 'required'
)
)
);
When a rule group is named identically to a controller class/function it will be used automatically when the run() function is invoked from that class/function.
Using Arrays as Field Names
The Form Validation class supports the use of arrays as field names. Consider this example:
<input type="text" name="options[]" value="" size="50" />
If you do use an array as a field name, you must use the EXACT array name in the Helper Functions that require the field name, and as your Validation Rule field name.
For example, to set a rule for the above field you would use:
$this->form_validation->set_rules('options[]', 'Options', 'required');
Or, to show an error for the above field you would use:
<?php echo form_error('options[]'); ?>
Or to re-populate the field you would use:
<input type="text" name="options[]" value="<?php echo set_value('options[]'); ?>" size="50" />
You can use multidimensional arrays as field names as well. For example:
<input type="text" name="options[size]" value="" size="50" />
Or even:
<input type="text" name="sports[nba][basketball]" value="" size="50" />
As with our first example, you must use the exact array name in the helper functions:
<?php echo form_error('sports[nba][basketball]'); ?>
If you are using checkboxes (or other fields) that have multiple options, don't forget to leave an empty bracket after each option, so that all selections will be added to the POST array:
<input type="checkbox" name="options[]" value="red" />
<input type="checkbox" name="options[]" value="blue" />
<input type="checkbox" name="options[]" value="green" />
Or if you use a multidimensional array:
<input type="checkbox" name="options[color][]" value="red" />
<input type="checkbox" name="options[color][]" value="blue" />
<input type="checkbox" name="options[color][]" value="green" />
When you use a helper function you'll include the bracket as well:
<?php echo form_error('options[color][]'); ?>
Rule Reference
The following is a list of all the native rules that are available to use:
| Rule | Parameter | Description | Example |
|---|---|---|---|
| required | No | Returns FALSE if the form element is empty. | |
| matches | Yes | Returns FALSE if the form element does not match the one in the parameter. | matches[form_item] |
| min_length | Yes | Returns FALSE if the form element is shorter then the parameter value. | min_length[6] |
| max_length | Yes | Returns FALSE if the form element is longer then the parameter value. | max_length[12] |
| exact_length | Yes | Returns FALSE if the form element is not exactly the parameter value. | exact_length[8] |
| alpha | No | Returns FALSE if the form element contains anything other than alphabetical characters. | |
| alpha_numeric | No | Returns FALSE if the form element contains anything other than alpha-numeric characters. | |
| alpha_dash | No | Returns FALSE if the form element contains anything other than alpha-numeric characters, underscores or dashes. | |
| numeric | No | Returns FALSE if the form element contains anything other than numeric characters. | |
| integer | No | Returns FALSE if the form element contains anything other than an integer. | |
| is_natural | No | Returns FALSE if the form element contains anything other than a natural number: 0, 1, 2, 3, etc. | |
| is_natural_no_zero | No | Returns FALSE if the form element contains anything other than a natural number, but not zero: 1, 2, 3, etc. | |
| valid_email | No | Returns FALSE if the form element does not contain a valid email address. | |
| valid_emails | No | Returns FALSE if any value provided in a comma separated list is not a valid email. | |
| valid_ip | No | Returns FALSE if the supplied IP is not valid. | |
| valid_base64 | No | Returns FALSE if the supplied string contains anything other than valid Base64 characters. |
Note: These rules can also be called as discrete functions. For example:
$this->form_validation->required($string);
Note: You can also use any native PHP functions that permit one parameter.
Prepping Reference
The following is a list of all the prepping functions that are available to use:
| Name | Parameter | Description |
|---|---|---|
| xss_clean | No | Runs the data through the XSS filtering function, described in the Input Class page. |
| prep_for_form | No | Converts special characters so that HTML data can be shown in a form field without breaking it. |
| prep_url | No | Adds "http://" to URLs if missing. |
| strip_image_tags | No | Strips the HTML from image tags leaving the raw URL. |
| encode_php_tags | No | Converts PHP tags to entities. |
Note: You can also use any native PHP functions that permit one parameter, like trim, htmlspecialchars, urldecode, etc.
Function Reference
The following functions are intended for use in your controller functions.
$this->form_validation->set_rules();
Permits you to set validation rules, as described in the tutorial sections above:
$this->form_validation->run();
Runs the validation routines. Returns boolean TRUE on success and FALSE on failure. You can optionally pass the name of the validation group via the function, as described in: Saving Groups of Validation Rules to a Config File.
$this->form_validation->set_message();
Permits you to set custom error messages. See Setting Error Messages above.
Helper Reference
The following helper functions are available for use in the view files containing your forms. Note that these are procedural functions, so they do not require you to prepend them with $this->form_validation.
form_error()
Shows an individual error message associated with the field name supplied to the function. Example:
<?php echo form_error('username'); ?>
The error delimiters can be optionally specified. See the Changing the Error Delimiters section above.
validation_errors()
Shows all error messages as a string: Example:
<?php echo validation_errors(); ?>
The error delimiters can be optionally specified. See the Changing the Error Delimiters section above.
set_value()
Permits you to set the value of an input form or textarea. You must supply the field name via the first parameter of the function. The second (optional) parameter allows you to set a default value for the form. Example:
<input type="text" name="quantity" value="<?php echo set_value('quantity', '0'); ?>" size="50" />
The above form will show "0" when loaded for the first time.
set_select()
If you use a <select> menu, this function permits you to display the menu item that was selected. The first parameter must contain the name of the select menu, the second parameter must contain the value of each item, and the third (optional) parameter lets you set an item as the default (use boolean TRUE/FALSE).
Example:
<select name="myselect">
<option value="one" <?php echo set_select('myselect', 'one', TRUE); ?> >One</option>
<option value="two" <?php echo set_select('myselect', 'two'); ?> >Two</option>
<option value="three" <?php echo set_select('myselect', 'three'); ?> >Three</option>
</select>
set_checkbox()
Permits you to display a checkbox in the state it was submitted. The first parameter must contain the name of the checkbox, the second parameter must contain its value, and the third (optional) parameter lets you set an item as the default (use boolean TRUE/FALSE). Example:
<input type="checkbox" name="mycheck[]" value="1" <?php echo set_checkbox('mycheck[]', '1'); ?> />
<input type="checkbox" name="mycheck[]" value="2" <?php echo set_checkbox('mycheck[]', '2'); ?> />
set_radio()
Permits you to display radio buttons in the state they were submitted. This function is identical to the set_checkbox() function above.
<input type="radio" name="myradio" value="1" <?php echo set_radio('myradio', '1', TRUE); ?> />
<input type="radio" name="myradio" value="2" <?php echo set_radio('myradio', '2'); ?> />