WP Data Validation

<?php
/**!
 * Validation for general text with no html
 */
function validate_text_no_html($input) {
    //accept the input only after stripping out all html, extra white space etc!
    return sanitize_text_field($input);
}
/**!
 * Validation for general text with some html
 */
function validate_text_custom_html($input) {
    // accept only a few inline html elements
    $allowed_html = array(
        'a' => array('href' => array (),'title' => array ()),
        'b' => array(),
        'em' => array (),
        'i' => array (),
        'strong' => array()
    );

    // trim whitespace
    $valid_input    = trim($input);
    // find incorrectly nested or missing closing tags and fix markup
    $valid_input    = force_balance_tags($valid_input);
    // only the allowed HTML element names, attribute names and attribute values plus only sane HTML entities will occur
    $valid_input    = wp_kses( $valid_input, $allowed_html);

    return $valid_input;
}

/**!
 * Accept the input only when numeric
 */
function validate_text_numeric($input) {

    if ( is_int( $input) || is_float( $input) ) {

        return $input;

    } else {

        return intval( $input);

    }
}

/**!
 * Validation for only url
 */
function validate_text_url($input) {
    // trim whitespace
    $valid_input    = trim($input);
    //accept the input only when the url has been sanited for database usage with esc_url_raw()
    $valid_input    = esc_url_raw($valid_input);

    return $valid_input;
}

/**!
 * Validation for only email
 */
function validate_text_email($input) {
    //Strips out all characters that are not allowable in an email address.
    $valid_input    = sanitize_email($input);
    //accept the input only after the email has been validated
    $valid_input    = (is_email($valid_input)!== FALSE) ? $valid_input : '';

    return $valid_input;
}

/**!
 * Validation for checkbox
 */
function validate_checkbox($input) {
    // Our checkbox value is either 0 or 1
    if ( $input == 1 ) {

        return 1;

    } else {

        return 0;

    }
}

/**
 * Sanitize a value from a list of allowed values.
 *
 * @param  mixed    $input      The value to sanitize.
 * @param  mixed    $setting    The setting for which the sanitizing is occurring.
 */
function validate_choice_select_and_radio( $input, $setting ) {

    global $wp_customize;
    $field = $wp_customize->get_control( $setting->id );

    if ( array_key_exists( $input, $field->choices ) ) {

        return $input;

    } else {

        return $setting->default;

    }
}

/**!
 * Validation for only inline html
 */
function validate_textarea_inline_html($input) {
    $valid_input    = trim($input);     // trim whitespace
    $valid_input    = force_balance_tags($valid_input); // find incorrectly nested or missing closing tags and fix markup
    $valid_input    = addslashes($valid_input); //calls stripslashes then addslashes
    $valid_input    = wp_filter_kses($valid_input); //wp_filter_kses expects content to be escaped!
    $valid_input    = stripslashes($valid_input);   //calls stripslashes then addslashes

    return $valid_input;
}

/**!
 * Validation for no html
 */
function validate_textarea_no_html($input) {
    // need to add slashes still before sending to the database
    $valid_input    = addslashes($input);
    //accept the input only after stripping out all html, extra white space etc!
    $valid_input    = wp_filter_nohtml_kses($valid_input);
    $valid_input    = stripslashes($valid_input);   //calls stripslashes then addslashes

    return $valid_input;
}

/**!
 * Validation for allowed line breaks
 */
function validate_textarea_allow_line_breaks($input) {
    // need to add slashes still before sending to the database
    $valid_input    = addslashes($input);
    //accept the input only after stripping out all html, extra white space etc!
    $valid_input    = wp_strip_all_tags($valid_input);
    $valid_input    = stripslashes($valid_input);   //calls stripslashes then addslashes

    return $valid_input;
}