Widget checkbox array empty on update function

Question

I have a widget that is not passing checkbox state to $new_instance, specifically $instance[ 'posts' ]; if I dump $new_instance in the update function it is empty? All the other instance variables are fine and as expected?

  /**
     * Ouputs the options form on admin
     *
     * @param array $instance The widget options
     */
    public function form( $instance ) {

        if ( isset( $instance[ 'type' ] ) ) {
            $type = $instance[ 'type' ];
        }
        else {
            $type = __( 'Select Type', 'text_domain' );
        }

        if ( isset( $instance[ 'icon' ] ) ) {
            $icon = $instance[ 'icon' ];
        } else {
            $icon = __( 'Select Icon', 'text_domain' );
        }

        if ( isset( $instance[ 'title' ] ) ) {
            $title = $instance[ 'title' ];
        } else {
            $title = __( 'New title', 'text_domain' );
        }

        if ( isset( $instance[ 'posts' ] ) ) {
            $theposts['posts'] = $instance[ 'posts' ];
        }

        ?>
        <p>
        <label for="<?php echo $this->get_field_id( 'type' ); ?>"><?php _e( 'Type:' ); ?></label> 
        <select id="<?php echo $this->get_field_id('type'); ?>" name="<?php echo $this->get_field_name('type'); ?>" class="widefat" style="width:100%;">
            <?php
           $types = array('Select Type', 'rental' => 'Rental', 'cloud' => 'Cloud', 'konnect' => 'Connect', 'support' => 'Support');
            foreach($types as $type => $v) { ?>

            <?php if ( isset( $instance[ 'type' ] ) ) { ?>
                <option <?php if ( $instance['type'] == $type ) echo 'selected="selected"'; ?> value="<?php echo $type; ?>"><?php echo $v; ?></option>
            <?php } else { ?>
                <option  value="<?php echo $type; ?>"><?php echo $v; ?></option>
            <?php } ?>

        <?php } ?>      
        </select>
        </p>

        <p>
        <label for="<?php echo $this->get_field_id( 'icon' ); ?>"><?php _e( 'icon:' ); ?></label> 
        <select id="<?php echo $this->get_field_id('icon'); ?>" name="<?php echo $this->get_field_name('icon'); ?>" class="widefat" style="width:100%;">
            <?php
        $icons = array('Select Icon', 'monitor', 'users', 'switch', 'cloud', 'arrows-ccw', 'user', 'user-add', 'link', 'lock', 'thumbs-up', 'upload-cloud','login','database','install','lifebuoy','signal','network');
            foreach($icons as $ico) { ?>

            <?php if ( isset( $instance[ 'icon' ] ) ) { ?>
                <option <?php if ( $instance['icon'] == $ico ) echo 'selected="selected"'; ?> value="<?php echo $ico; ?>"><?php echo $ico; ?></option>
            <?php } else { ?>
                <option  value="<?php echo $ico; ?>"><?php echo $ico; ?></option>
            <?php } ?>

            <?php } ?>       
       </select>
        </p>


        <p>
        <label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label> 
        <input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>" />
        </p>


            <p>
            <label for="<?php echo $this->get_field_id( 'posts' ); ?>"><?php _e( 'Post to show:' ); ?></label><br />

            <?php
            if ($instance ['type'] == 'konnect') {$instance ['type'] == 'konect';}
            $newargs = array('posts_per_page' => -1, 'post_type' => $instance[ 'type' ], 'post_parent' => 0,);
            $specificposts = get_posts( $newargs ); ?>

            <?php foreach($specificposts as $name => $specificpost) {  ?>


                <?php if ( in_array( $specificpost->ID, $instance[ 'posts' ] ) ) { ?>
                    <p class="<?php echo $specificpost->ID; ?>"><input type="checkbox" name="<?php echo $instance[ 'posts' ][$specificpost->ID]; ?>" value="<?php echo $specificpost->ID; ?>" checked="checked" /> <label><?php echo $specificpost->post_title; ?></label></p>
                <?php  } else { ?>
                    <p class="<?php echo $specificpost->ID; ?>"><input type="checkbox" name="<?php echo $this->get_field_name('posts'). '['.$specificpost->ID.']'; ?>" value="<?php echo $specificpost->ID; ?>" /> <label><?php echo $specificpost->post_title; ?></label></p>
                <?php }  ?>
          <?php } ?>

        </p>            

    <?php }

Answer 1

I suspect this is mostly happening because down towards the bottom, you've got an input that's not using $this->get_field_name() (the first of the two checkbox inputs).

Try using $this->get_field_name() as you did in the "then" clause of that section of code and it should be OK.

Not much else wrong that I can see.