WordPress - how to add custom meta box to a specific admin page?

Question

How can I add my custom meta box to a specific page only on the admin page?

Here is my custom meta box code which I got it from here:

/**
 * Adds a meta box to the post editing screen
 */
function prfx_custom_meta() {
    add_meta_box( 'prfx_meta', __( 'Meta Box Title', 'prfx-textdomain' ), 'prfx_meta_callback', array( 'post', 'page') );
}

add_action( 'add_meta_boxes', 'prfx_custom_meta' );


/**
 * Outputs the content of the meta box
 */
function prfx_meta_callback( $post ) {
    // echo 'This is a meta box';
    wp_nonce_field( basename( __FILE__ ), 'prfx_nonce' );
    $prfx_stored_meta = get_post_meta( $post->ID );

    if ($post_slug == 'home') {
    ?>

    <p>
        <label for="meta-text" class="prfx-row-title"><?php _e( 'Example Text Input', 'prfx-textdomain' )?></label>
        <input type="text" name="meta-text" id="meta-text" value="<?php if ( isset ( $prfx_stored_meta['meta-text'] ) ) echo $prfx_stored_meta['meta-text'][0]; ?>" />
    </p>

    <?php
    }
}

/**
 * Saves the custom meta input
 */
function prfx_meta_save( $post_id ) {

    // Checks save status
    $is_autosave = wp_is_post_autosave( $post_id );
    $is_revision = wp_is_post_revision( $post_id );
    $is_valid_nonce = ( isset( $_POST[ 'prfx_nonce' ] ) && wp_verify_nonce( $_POST[ 'prfx_nonce' ], basename( __FILE__ ) ) ) ? 'true' : 'false';

    // Exits script depending on save status
    if ( $is_autosave || $is_revision || !$is_valid_nonce ) {
        return;
    }

    // Checks for input and sanitizes/saves if needed
    if( isset( $_POST[ 'meta-text' ] ) ) {
        update_post_meta( $post_id, 'meta-text', sanitize_text_field( $_POST[ 'meta-text' ] ) );
    }

}
add_action( 'save_post', 'prfx_meta_save' );

I just want to add the meta box to my home page. but now on other pages and posts I still see the meta title:

Any idea how I stop it from showing on other pages and posts?

EDIT:

/**
 * Add custom meta box to a specific page in the WP admin.
 *
 * @ http://themefoundation.com/wordpress-meta-boxes-guide/
 * @ http://www.farinspace.com/page-specific-wordpress-meta-box/
 */
function my_meta_init() {
    // Get post/page ID.
    $post_id = $_GET['post'] ? $_GET['post'] : $_POST['post_ID'] ;

    // Get post/page slug.
    $post = get_post($post_id);
    $slug = $post->post_name;

    // checks for post/page slug.
    if ($slug == 'home') {
        add_meta_box( 'prfx_meta', __( 'Meta Box Title', 'prfx-textdomain' ), 'prfx_meta_callback', array( 'post', 'page') );
    }
    add_action( 'add_meta_boxes', 'prfx_meta_save' );
}
add_action('admin_init','my_meta_init');

/**
 * Outputs the content of the meta box
 */
function prfx_meta_callback( $post ) {
    // echo 'This is a meta box';
    wp_nonce_field( basename( __FILE__ ), 'prfx_nonce' );
    $prfx_stored_meta = get_post_meta( $post->ID );
    ?>

    <p>
        <label for="meta-text" class="prfx-row-title"><?php _e( 'Example Text Input', 'prfx-textdomain' )?></label>
        <input type="text" name="meta-text" id="meta-text" value="<?php if ( isset ( $prfx_stored_meta['meta-text'] ) ) echo $prfx_stored_meta['meta-text'][0]; ?>" />
    </p>

    <?php
}

/**
 * Saves the custom meta input
 */
function prfx_meta_save( $post_id ) {
    // Checks save status
    $is_autosave = wp_is_post_autosave( $post_id );
    $is_revision = wp_is_post_revision( $post_id );
    $is_valid_nonce = ( isset( $_POST[ 'prfx_nonce' ] ) && wp_verify_nonce( $_POST[ 'prfx_nonce' ], basename( __FILE__ ) ) ) ? 'true' : 'false';

    // Exits script depending on save status
    if ( $is_autosave || $is_revision || !$is_valid_nonce ) {
        return;
    }

    // Checks for input and sanitizes/saves if needed
    if( isset( $_POST[ 'meta-text' ] ) ) {
        update_post_meta( $post_id, 'meta-text', sanitize_text_field( $_POST[ 'meta-text' ] ) );
    }

}
add_action( 'save_post', 'prfx_meta_save' );

Answer 1

Use this js it will resolve your problem. this will show the metabox on perticular template or page..

  (function($){
    $(document).ready(function() {

        var $page_template = $('#pageid')
            ,$metabox1 = $('#metaboxid');

        $page_template.change(function() {
            if ($(this).val() == 'templatename') {
                $metabox1.show();

            } else {
                $metabox1.hide();

            }
        }).change();

    });
    })(jQuery);

if you are using this in admin then use admin hook and add this code in functions.php

Answer 2

You can try this condition

add_action('admin_init','my_meta_init');
function my_meta_init()
{
   $post_id = $_GET['post'] ? $_GET['post'] : $_POST['post_ID'] ;
   // checks for post/page ID
   if ($post_id == '84')
   {
   add_meta_box('my_all_meta_1', 'My Custom Meta Box 1', 'my_meta_setup_1',   'page', 'normal', 'high');
   }
add_action('save_post','my_meta_save');
}

Answer 3

/**
 * Adds a meta box to the post editing screen
 */
function prfx_custom_meta() {
    $current_user = wp_get_current_user();
    if($current_user->roles[0] === 'administrator') {
        add_meta_box( 'prfx_meta', __( 'Meta Box Title', 'prfx-textdomain' ), 'prfx_meta_callback', array( 'post', 'page') );
    }
}

add_action( 'add_meta_boxes', 'prfx_custom_meta' );


/**
 * Outputs the content of the meta box
 */
function prfx_meta_callback( $post ) {
    // echo 'This is a meta box';
    wp_nonce_field( basename( __FILE__ ), 'prfx_nonce' );
    $prfx_stored_meta = get_post_meta( $post->ID );

    if ($post_slug == 'home') {
    ?>

    <p>
        <label for="meta-text" class="prfx-row-title"><?php _e( 'Example Text Input', 'prfx-textdomain' )?></label>
        <input type="text" name="meta-text" id="meta-text" value="<?php if ( isset ( $prfx_stored_meta['meta-text'] ) ) echo $prfx_stored_meta['meta-text'][0]; ?>" />
    </p>

    <?php
    }
}

/**
 * Saves the custom meta input
 */
function prfx_meta_save( $post_id ) {

    // Checks save status
    $is_autosave = wp_is_post_autosave( $post_id );
    $is_revision = wp_is_post_revision( $post_id );
    $is_valid_nonce = ( isset( $_POST[ 'prfx_nonce' ] ) && wp_verify_nonce( $_POST[ 'prfx_nonce' ], basename( __FILE__ ) ) ) ? 'true' : 'false';

    // Exits script depending on save status
    if ( $is_autosave || $is_revision || !$is_valid_nonce ) {
        return;
    }

    // Checks for input and sanitizes/saves if needed
    if( isset( $_POST[ 'meta-text' ] ) ) {
        update_post_meta( $post_id, 'meta-text', sanitize_text_field( $_POST[ 'meta-text' ] ) );
    }

}
add_action( 'save_post', 'prfx_meta_save' );