how to get post thumbnail using post id in wordpress? - php

Question

I am trying to get the post thumbnail using post_id,but i am getting so many problems.
Iam calling the function in a separate php file in theme directory
echo get_the_post_thumbnail('637');
Fatal error: Call to undefined function get_the_post_thumbnail() in ...
1)can we get the thumbnail using post_id
or
2)can we get the image source using post_id
please any body help me
Thanks in advance

Answer 1

Try this
global $post;
$thumb = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'post');
echo $thumb[0];

Answer 2

In your case you make a small mistake that you put the single quote inside the function when function require an integer value.
echo get_the_post_thumbnail('637');
Bellow code are valid try it.
Simple Form
echo get_the_post_thumbnail(637);
Size Specified Form where second argument is the size of the image.
echo get_the_post_thumbnail(637, array(100,100));
also you can try bellow code also
get_the_post_thumbnail(637); // without parameter -> Thumbnail
get_the_post_thumbnail(637, 'thumbnail'); // Thumbnail
get_the_post_thumbnail(637, 'medium'); // Medium resolution
get_the_post_thumbnail(637, 'large'); // Large resolution
get_the_post_thumbnail(637, 'full'); // Original resolution
Also you can refer to the WordPress codex Here.
I am also going to write a full post on this topic on my blog

Answer 3

Use Require_once Or include_once
require_once('/the/path/to/your/wp-blog-header.php');
include_once('wp-blog-header.php' );
get_the_post_thumbnail($post_id); // without parameter -> Thumbnail
get_the_post_thumbnail($post_id, 'thumbnail'); // Thumbnail
get_the_post_thumbnail($post_id, 'medium'); // Medium resolution
get_the_post_thumbnail($post_id, 'large'); // Large resolution
get_the_post_thumbnail($post_id, 'full'); // Original resolution
get_the_post_thumbnail($post_id, array(100,100) ); // Other resolutions
Out side of loop
global $post;
if (has_post_thumbnail( $post->ID ) ){
//
get_the_post_thumbnail($post->ID);
//
}

Answer 4

Vallabh's solution works. This is how I use it as a background image:
<?php if (has_post_thumbnail( $post->ID ) ) {
$image = wp_get_attachment_image_src( get_post_thumbnail_id(637), 'thumbnail' );
$image = $image[0];
} ?>
<div style="background-image: url(<?php echo $image; ?>)"> ... </div>

Answer 5

Create a post template..look like this(post_temp.php)
<?php
$args=array('order'=> 'DESC', 'posts_per_page'=>get_option('posts_per_page'));
$query=new WP_Query($args);
if( $query->have_posts()):
while( $query->have_posts()): $query->the_post();
{
echo get_the_post_thumbnail($post->ID);
}
endwhile;
else:
endif;
?>