Wordpress Meta Box Form Data Not Saving - php

Question

My plugin is about adding FAQs to your desired page.
I have added a form within a metabox in the 'Add New Question'.
When I feed values in the form, the form data does save in
the database, but does not retain or show the values (selected)
in the form when the page updates/publishes.
Instead, the form shows the previous non-selected values (even though the
selected values do show up in the database).
<?php
function faq_manage_things($post)
{
global $post;
$post_id= $post->ID;
wp_nonce_field(basename(__FILE__),'faqs_questions_nonce');
$faq_stored_meta= get_post_meta($post->ID);
?>
<div class="wrap">
<p>
<label for="meta-select" class="prfx-row-title"><?php _e( 'Example Select Input', 'prfx-textdomain' )?></label>
<select name="meta-select" id="meta-select">
<option value="select-one" <?php if ( isset ( $prfx_stored_meta['meta-select'] ) ) selected( $prfx_stored_meta['meta-select'][0], 'select-one' ); ?>><?php _e( 'One', 'prfx-textdomain' )?></option>';
<option value="select-two" <?php if ( isset ( $prfx_stored_meta['meta-select'] ) ) selected( $prfx_stored_meta['meta-select'][0], 'select-two' ); ?>><?php _e( 'Two', 'prfx-textdomain' )?></option>';
</select>
</p>
<!-- TEXT AREA -->
<p>
<label for="meta-textarea" class="prfx-row-title"><?php _e( 'Example Textarea Input', 'prfx-textdomain' )?></label>
<textarea name="meta-textarea" id="meta-textarea"><?php if ( isset ( $prfx_stored_meta['meta-textarea'] ) ) echo $prfx_stored_meta['meta-textarea'][0]; ?></textarea>
</p>
<!-- CHECKBOXES -->
<p>
<span class="prfx-row-title"><?php _e( 'Example Checkbox Input', 'prfx-textdomain' )?></span>
<div class="prfx-row-content">
<label for="meta-checkbox">
<input type="checkbox" name="meta-checkbox" id="meta-checkbox" value="yes" <?php if ( isset ( $prfx_stored_meta['meta-checkbox'] ) ) checked( $prfx_stored_meta['meta-checkbox'][0], 'yes' ); ?> /><?php _e( 'Checkbox label', 'prfx-textdomain' )?>
</label>
<label for="meta-checkbox-two">
<input type="checkbox" name="meta-checkbox-two" id="meta-checkbox-two" value="yes" <?php if ( isset ( $prfx_stored_meta['meta-checkbox-two'] ) ) checked( $prfx_stored_meta['meta-checkbox-two'][0], 'yes' ); ?> /><?php _e( 'Another checkbox', 'prfx-textdomain' )?>
</label>
</div>
</p>
</div>
<?php
}
global $post;
function faq_meta_save( $post_id ) {
global $post;
$post_id= $post->ID;
$is_autosave = wp_is_post_autosave( $post_id );
$is_revision = wp_is_post_revision( $post_id );
$is_valid_nonce = ( isset( $_POST[ 'faqs_questions_nonce' ] ) && wp_verify_nonce( $_POST['faqs_questions_nonce'],basename(__FILE__)) )? 'true' : 'false';
if ( $is_autosave || $is_revision || !$is_valid_nonce )
{return;} //exit
if( isset( $_POST[ 'meta-select' ] ) )
{ update_post_meta( $post_id, 'meta-select', $_POST[ 'meta-select' ] ); }
if( isset( $_POST[ 'meta-textarea' ] ) ) {
update_post_meta( $post_id, 'meta-textarea', sanitize_text_field($_POST[ 'meta-textarea' ]) ); }
// Checks for input and saves
if( isset( $_POST[ 'meta-checkbox' ] ) ) {
update_post_meta( $post_id, 'meta-checkbox', 'yes' );}
else {
update_post_meta( $post_id, 'meta-checkbox', '' ); }
// Checks for input and saves
if( isset( $_POST[ 'meta-checkbox-two' ] ) ) {
update_post_meta( $post_id, 'meta-checkbox-two', 'yes' );}
else {
update_post_meta( $post_id, 'meta-checkbox-two', '' ); }
}
add_action('save_post','faq_meta_save');

Answer 1

You have to check if you have the meta_key duplicated in the database for the same post_id. Also, I recommend you to use underscores instead of hyphens in the meta_key names. Try this code where the meta_data of the post_id is deleted and then is added the new value.
Try this:
<?php
function faq_manage_things($post)
{
global $post;
$post_id= $post->ID;
wp_nonce_field(basename(__FILE__),'faqs_questions_nonce');
$faq_stored_meta= get_post_meta($post->ID);
?>
<div class="wrap">
<p>
<label for="meta-select" class="prfx-row-title"><?php _e( 'Example Select Input', 'prfx-textdomain' )?></label>
<select name="meta-select" id="meta-select">
<option value="select-one" <?php if ( isset ( $prfx_stored_meta['meta_select'] ) ) selected( $prfx_stored_meta['meta_select'][0], 'select-one' ); ?>><?php _e( 'One', 'prfx-textdomain' )?></option>';
<option value="select-two" <?php if ( isset ( $prfx_stored_meta['meta_select'] ) ) selected( $prfx_stored_meta['meta_select'][0], 'select-two' ); ?>><?php _e( 'Two', 'prfx-textdomain' )?></option>';
</select>
</p>
<!-- TEXT AREA -->
<p>
<label for="meta-textarea" class="prfx-row-title"><?php _e( 'Example Textarea Input', 'prfx-textdomain' )?></label>
<textarea name="meta-textarea" id="meta-textarea"><?php if ( isset ( $prfx_stored_meta['meta_textarea'] ) ) echo $prfx_stored_meta['meta_textarea'][0]; ?></textarea>
</p>
<!-- CHECKBOXES -->
<p>
<span class="prfx-row-title"><?php _e( 'Example Checkbox Input', 'prfx-textdomain' )?></span>
<div class="prfx-row-content">
<label for="meta-checkbox">
<input type="checkbox" name="meta-checkbox" id="meta-checkbox" value="yes" <?php if ( isset ( $prfx_stored_meta['meta_checkbox'] ) ) checked( $prfx_stored_meta['meta_checkbox'][0], 'yes' ); ?> /><?php _e( 'Checkbox label', 'prfx-textdomain' )?>
</label>
<label for="meta-checkbox-two">
<input type="checkbox" name="meta-checkbox-two" id="meta-checkbox-two" value="yes" <?php if ( isset ( $prfx_stored_meta['meta_checkbox_two'] ) ) checked( $prfx_stored_meta['meta_checkbox_two'][0], 'yes' ); ?> /><?php _e( 'Another checkbox', 'prfx-textdomain' )?>
</label>
</div>
</p>
</div>
<?php
}
global $post;
function faq_meta_save( $post_id ) {
global $post;
$post_id= $post->ID;
$is_autosave = wp_is_post_autosave( $post_id );
$is_revision = wp_is_post_revision( $post_id );
$is_valid_nonce = ( isset( $_POST[ 'faqs_questions_nonce' ] ) && wp_verify_nonce( $_POST['faqs_questions_nonce'],basename(__FILE__)) )? 'true' : 'false';
if ( $is_autosave || $is_revision || !$is_valid_nonce )
{return;} //exit
if( isset( $_POST[ 'meta-select' ] ) ) {
remove_post_meta( $post_id, 'meta_select', $_POST[ 'meta-select' ] );
add_post_meta( $post_id, 'meta_select', $_POST[ 'meta-select' ] );
}
if( isset( $_POST[ 'meta-textarea' ] ) ) {
remove_post_meta( $post_id, 'meta_textarea', sanitize_text_field($_POST[ 'meta-textarea' ]) );
add_post_meta( $post_id, 'meta_textarea', sanitize_text_field($_POST[ 'meta-textarea' ]) );
}
// Checks for input and saves
if( isset( $_POST[ 'meta-checkbox' ] ) ) {
remove_post_meta( $post_id, 'meta_checkbox', 'yes' );
add_post_meta( $post_id, 'meta_checkbox', 'yes' );
}
else {
remove_post_meta( $post_id, 'meta_checkbox');
}
// Checks for input and saves
if( isset( $_POST[ 'meta-checkbox-two' ] ) ) {
remove_post_meta( $post_id, 'meta_checkbox-two', 'yes' );
add_post_meta( $post_id, 'meta_checkbox-two', 'yes' );
}
else {
remove_post_meta( $post_id, 'meta_checkbox-two');
}
}
add_action('save_post','faq_meta_save');