Correctly Using checked function of Wordpress

Question

In the Public Function Update this code is sitting →

`public function update($new_instance, $old_instance)

      $instance['description_box'] = $new_instance['description_box'];

In the public function widget, this code is sitting →

public function widget($args, $instance) {

    $description_box = $instance[ 'description_box' ] ? 'true' : 'false';

In the public function→

public function form( $instance ) {

This code is sitting →

<p> <input class="checkbox" type="checkbox" <?php checked( $instance[ 'description_box' ], 'on' ); ?> id="<?php echo $this->get_field_id( 'description_box' ); ?>" name="<?php echo $this->get_field_name( 'description_box' ); ?>" />
        <label for="<?php echo $this->get_field_id( 'description_box' ); ?>">Check whether to display description or not</label>
        </p>

Now what i want is when the condition is true i.e. the box is checked then execute some code.

If ($description_box is true) {
<p>some text</p>

}

How to correctly write this using this →https://codex.wordpress.org/Function_Reference/checked

Update →

I tried using this →

<?php if($description_box==0){ ?>
                                    <p><</p>
                                    <?php } ?>

But the problem is if the widget is in 2 different sidebars, in one checkbox ticked and in another not, but the result is same in both i.e. it either displays <p></p> or not based on the either $description_box is set to 0/1 or true/false in the php if condition. whats the remedy?

Answer 1

Now, based on your full code, there's 3 problems:

Line 60 of your code is missing a semi colon and throwing a fatal error. So:

$instance['description_check_box'] = $new_instance['description_check_box'] 

Should be:

$instance['description_check_box'] = $new_instance['description_check_box']; 

On line 66, you're using strings instead of proper boolean true or false values. Both if these are 'truthy' (see this answer to another question for what that means), so will both resolve as true if used in an if statement. if ('false') is true. So:

$description_check_box = $instance[ 'description_check_box' ] ? 'true' : 'false';

Should be:

$description_check_box = $instance[ 'description_check_box' ] ? true : false;

On line 121 you haven't got on in quotes, so you're comparing $description_check_box to the constant on. This should be in quotes if you want to check if the value of $description_check_box is on. So:

<?php if($description_check_box==on){ ?>

Should be:

<?php if($description_check_box=='on'){ ?>

BUT. This still won't work. Because you'd be setting $description_check_box to true or false based on whether it's checked on line 66, but later you're checking if the value is 'on'.

You either need to set the value of $description_check_box to 'on', or change your comparison to checking if $description_check_box is true.

You should also use isset() before using $instance['description_check_box'], because otherwise you'll get an undefined index notice in the customiser when WP_Debug is enabled.

Refer to my other answer for my approach, which avoids all these problems.

Answer 2

Here's a full implementation of a simple widget with a checkbox that hides/shows something on the front end:

class Checkbox_Widget extends WP_Widget {
    public function __construct() {
        parent::__construct(
            'checkbox-widget',
            'Checkbox widget',
            array(
                'classname' => 'widget_checkbox',
            )
        );
    }

    public function widget($args, $instance) {
        $checkbox = isset( $instance['checkbox'] ) ? $instance['checkbox'] : false;

        $args['before_widget'];

        if ( $checkbox === 'on' ) {
            echo 'I\'m checked!';
        }

        $args['after_widget'];
    }

    public function form( $instance ) {
        $checkbox = isset( $instance['checkbox'] ) ? $instance['checkbox'] : false;
        ?>

        <p><input type="checkbox" id="<?php echo $this->get_field_id( 'checkbox' ); ?>" name="<?php echo $this->get_field_name( 'checkbox' ); ?>" <?php checked( $checkbox, 'on' ); ?>>

        <?php
    }

    public function update( $new_instance, $old_instance ) {
        $new_instance['checkbox'] = $new_instance['checkbox'] === 'on' ? 'on' : false;

        return $new_instance;
    }
}

Based on you answers to my comment, I think we're you're going wrong is not getting the current value of the checkbox correctly. See, in my example, how the value of $instance['checkbox'] is being set to on if it's checked, and then in the widget I'm checking if it equals on when outputting.