In this post i am going to discuss about the various methods of using the codeigniter validation library.

Lets start by doing a simple example.

Here is our form for this example. This form is contained in the view file.

Username
Password

First thing we have to do to use the validation library is to load the library. Validation library should be loaded in the constructer of the controller class you want.

load->library('validation');
        }
}
?>

After loading the library we can use validation functions of the library inside this controller class. Example is given below.

validation->set_error_delimiters('
', '
');

        // Validation rules
        $rules['username']= "trim|required";
        $rules['password']= "trim|required";
        $this->validation->set_rules($rules);

        $fields['username']             = 'My Username';
        $fields['password']             = 'My Password';
        $this->validation->set_fields($fields);

        // Validate input data
        if ($this->validation->run() == FALSE) {
                $this->message = $this->validation->error_string;
        }else {
                // Proceed with other methods in the function
        }
}
?>

In the above code sample inside the login method we have specified the error delimeters as

. That means when ever error is generated the each error message will be displayed inside

tag.

Next we have to specify the validation rules for the fields. We set validation fields in an array called $rules. username and password are the input field names. Validation rules have to be given one by one seperated by | in a string. In this example i have used trim and required validators. These two are built in validators in Code Igniter.

Set the rule names in $rulearray and set to validation object using followiing code.

$this->validation->set_rules($rules);

Then we have to specify the display name of the error message. Set the display names in $field array and set to validation object using followiing code.

$this->validation->set_fields($fields);

If we dont specify it the system will automatically use the field name as display name of the error. Here i have given ‘My Username’ and ‘My Password’ as the display values. So if we keep the fields empty and click submit button following error messages will be generated.

My Username is required
My Password is required

If we dont specify the display names error messages will be like the following.

username is required
password is required

Then we call the run method to start validation. If there are errors in the input values for the given fields, validation object will return an error string and we have to return it to the view using

$this->message = $this->validation->error_string;

Otherwise we can continue to call other function in the process.

When we call the run method in the validation library it will automatically split the rules string in to validation rules. Then the function executes the validation methods one by one.

Example :

               // Cycle through the rules and test for errors
                foreach ($this->_rules as $field => $rules)
                {
                        //Explode out the rules!
                        $ex = explode('|', $rules);
                }

Here the loop runs two times for username and password. First it expldes and splits rules of usernames into an array called $ex.Then it takes rules one by one and executes it.

Once a rule is identified it will automatically take the specified parametr values from $_POST array and validates against the rule.

Code Igniter Validation Library Rules

Rule	Description
required	Returns FALSE if the form element is empty.
matches	Returns FALSE if the form element does not match the one in the parameter. matches[form_item]
min_length	Returns FALSE if the form element is shorter then the parameter value. min_length[6]
max_length	Returns FALSE if the form element is longer then the parameter value. max_length[12]
exact_length	Returns FALSE if the form element is not exactly the parameter value. exact_length[8]
alpha	Returns FALSE if the form element contains anything other than alphabetical characters.
alpha_numeric	Returns FALSE if the form element contains anything other than alpha-numeric characters.
alpha_dash	Returns FALSE if the form element contains anything other than alpha-numeric characters, underscores or dashes.
numeric	Returns FALSE if the form element contains anything other than numeric characters.
integer	Returns FALSE if the form element contains anything other than an integer.
valid_email	Returns FALSE if the form element does not contain a valid email address.
valid_emails	Returns FALSE if any value provided in a comma separated list is not a valid email.
valid_ip	Returns FALSE if the supplied IP is not valid.
valid_base64	Returns FALSE if the supplied string contains anything other than valid Base64 characters.

After submitiing the form if it contains any errors we need to display error messages to the user as well as keep the values of the fields which do not have any errors. We can do this by using set_value method.

Username

/>

In the next post about validation in CodeIgniter i am going to show you how to create Custom validation classes and custom rules. Date range validations, multiple select box validation , percentage , between and many more rules will be provided. So feel free to comment about your ideas and requirements relating to this topic.