Contact Form 7 – Custom Validation

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I need to validate just one field (called ‘Instance’) to accept lowercase ASCII letters and numbers only, the first character also has to be a letter not a number. It will accept uppercase characters but we will need it to lowercase them on input. So if someone uses the instance name McDonalds it will be lowercased to mcdonalds (not just with CSS). Spaces are not allowed either.

Is this possible with CF7? If so please explain how.

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I’ve already tried this custom validation method but even with the preset custom validation in the file it was just displaying the field shortcode rather than the field itself.

Thanks

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6 comments

  1. From contactform7.com on Custom Validation → Validation as a Filter:

    In Contact Form 7, a user-input validation is implemented as a filter
    function. The filter hook used for the validation varies depending on
    the type of form-tag and is determined as: wpcf7_validate_ + {type of
    the form-tag}. So, for text form-tags, the filter hook
    wpcf7_validate_text is used. Likewise, wpcf7_validate_email* is used
    for email* form-tags.

    Let’s say you have the following email fields in a form:

      Email:         [email* your-email]
  Confirm email: [email* your-email-confirm]

    The following listing shows code that verifies whether the two fields
    have identical values.

    add_filter('wpcf7_validate_email*', 'custom_email_confirmation_validation_filter', 20, 2);

function custom_email_confirmation_validation_filter($result, $tag) {
    $tag = new WPCF7_FormTag($tag);

    if ('your-email-confirm' == $tag->name) {
        $your_email = isset($_POST['your-email']) ? trim($_POST['your-email']) : '';
        $your_email_confirm = isset($_POST['your-email-confirm']) ? trim($_POST['your-email-confirm']) : '';

        if ($your_email != $your_email_confirm) {
            $result->invalidate($tag, "Are you sure this is the correct address?");
        }
    }
    return $result;
}

    Two parameters will be passed to the filter function: $result and
    $tag. $result is an instance of WPCF7_Validation class that manages a
    sequence of validation processes. $tag is an associative array
    composed of given form-tag components; as you saw in the previous
    recipe, you can use WPCF7_FormTag class to handle this type of data.

    Look through the inside of the filter function. First, check the name
    of the form-tag to ensure the validation is applied only to the
    specific field (your-email-confirm).

    The two email field values are then compared, and if they don’t match,
    $result->invalidate() will be called. You need to pass two parameters
    to the invalidate() method: the first parameter should be the $tag
    variable, and the second parameter is the validation error message
    that you want the field to display.

    Lastly, don’t forget to return the $result.

  2. // Add custom validation for CF7 form fields

    function is_company_email($email){ // Check against list of common public email providers & return true if the email provided *doesn't* match one of them
        if(
                preg_match('/@gmail.com/i', $email) ||
                preg_match('/@hotmail.com/i', $email) ||
                preg_match('/@live.com/i', $email) ||
                preg_match('/@msn.com/i', $email) ||
                preg_match('/@aol.com/i', $email) ||
                preg_match('/@yahoo.com/i', $email) ||
                preg_match('/@inbox.com/i', $email) ||
                preg_match('/@gmx.com/i', $email) ||
                preg_match('/@me.com/i', $email)
        ){
                return false; // It's a publicly available email address
        }else{
                return true; // It's probably a company email address
        }
}
function your_validation_filter_func($result,$tag){
        $type = $tag['type'];
        $name = $tag['name'];
        if('yourid' == $value){ // Only apply to fields with the form field name of "company-email"
                $the_value = $_POST[$name];
                if(!is_company_email($the_value)){ // Isn't a company email address (it matched the list of free email providers)
                        $result['valid'] = false;
                        $result->invalidate( $tag, wpcf7_get_message( 'invalid_email' ));
                }
        }
        return $result;
}

 add_filter( 'wpcf7_validate_email', 'your_validation_filter_func', 10, 2 ); 

// Email field or contact number field
  add_filter( 'wpcf7_validate_email*', 'your_validation_filter_func', 10, 2 );     // Req. Email field or contact number

  3. I had a similar issue for validating name fields, I added the following code in my functions.php, you could customize it by changing the regex

    function my_wpcf7_validate_text( $result, $tag ) {

    $type = $tag['type'];
    $name = $tag['name'];
    $value = $_POST[$name] ;

    if ( strpos( $name , 'name' ) !== false ){
        $regex = '/^[a-zA-Z]+$/';
        $Valid = preg_match($regex,  $value, $matches );
        if ( $Valid > 0 ) {
        } else {
            $result->invalidate( $tag, wpcf7_get_message( 'invalid_name' ) );
        }
    }
    return $result;
}
add_filter( 'wpcf7_validate_text*', 'my_wpcf7_validate_text' , 10, 2 );

add_filter( 'wpcf7_messages', 'mywpcf7_text_messages' );
function mywpcf7_text_messages( $messages ) {
    return array_merge( $messages, array(
        'invalid_name' => array(
            'description' => __( "Name is invalid", 'contact-form-7' ),
            'default' => __( 'Name seems invalid.', 'contact-form-7' )
        )
    ));
}

  5. You can add your own custom validation for a form field input by using the add_filter function.

    For adding a custom validation for a textarea field you can add the following inside functions.php file in the root directory of your theme.

    add_filter( 'wpcf7_validate_textarea*', 'custom_textarea_validation_filter', 1, 2 );

function custom_textarea_validation_filter( $result, $tag ) {
  $tag = new WPCF7_Shortcode($tag);
  $result = (object)$result;

  $name = 'project-synopsis';

  if ( $name == $tag->name ) {
    $project_synopsis = isset( $_POST[$name] ) ? trim( wp_unslash( (string) $_POST[$name] ) ) : '';

    if ( empty( $project_synopsis ) ) {
      $result->invalidate( $tag, "Please write a quick project synopsis." );
    }
  }

  return $result;
}

    For me the trick was to cast the $result parameter to an object, because the invalidate method that is used to add the error message didn’t work before casting.