is_unique in codeigniter form validation

The is_unique validation rule in CodeIgniter is used to check if a given field value in a form is unique in a specified database table. It is commonly used to validate unique values for fields such as email addresses, usernames, or any other field that should be unique within the database.

Here are the steps to use the is_unique validation rule in CodeIgniter form validation:

  1. Load the Form Validation library in your controller or autoload it in your configuration file.
  2. Set up the validation rules for your form inputs using the set_rules() method of the Form Validation library. Specify the field name and the validation rules you want to apply, including the is_unique rule.
  3. In the is_unique rule, you need to specify the table name and the field name to check for uniqueness. The syntax for the is_unique rule is: is_unique[table_name.field_name].
  4. After setting up the validation rules, you can run the validation using the run() method of the Form Validation library. This method will return a boolean value indicating whether the validation passed or failed.
  5. If the validation fails, you can retrieve the error messages using the validation_errors() function, which returns a string containing all the error messages.
  6. Display the error messages to the user or handle them accordingly.

Here is an example code snippet that demonstrates the usage of the is_unique validation rule:

// Load the Form Validation library
$this->load->library('form_validation');

// Set up the validation rules
$this->form_validation->set_rules('email', 'Email', 'required|valid_email|is_unique[users.email]');

// Run the validation
if ($this->form_validation->run() == false) {
    // Validation failed, display the error messages
    echo validation_errors();
} else {
    // Validation passed, do something
    // ...
}

In the example above, the is_unique rule is applied to the email field of the users table. If the entered email already exists in the users table, the validation will fail and the corresponding error message will be displayed.

Note that you need to replace email, users, and email with the actual field and table names in your application.

That's how you can use the is_unique validation rule in CodeIgniter form validation. It provides a convenient way to validate unique values in your forms before inserting them into the database.