How can I show custom field according to taxonomy?

Question

How I can show custom fields in my theme according to category?

For example in Laptop category show some custom fields and in Motherboard category show another fields.

Answer 1

In your loop use has_term( $term, $taxonomy, $post ).

1. Check if the post has the term you are searching for.
2. Check if there is a value for the custom field.
3. Print the value, but don’t forget to escape it.

if ( has_term( 'blue', 'product_color', $post ) )
{
    $field = get_post_meta( $post->ID, 'field_name', TRUE );

    if ( ! empty ( $field ) )
        echo esc_html( $field );
}

Answer 2

If I understand the question OP want to check if a product has a category in woocommerce (the taxonomy is 'product_cat') and show product attributes according to that category. E.G. if a product is in 'Laptop' show 'CPU' and 'Ram' custom fields, if product is in 'Hard Disk' category show 'Capacity' and 'RPM' custom fields.

Am I right? If so you have to add something like this in your functions.php

function my_product_fields( $postid = 0 ) {
  if ( ! intval($postid) ) {
    global $post;
    if ( empty($post) || ! is_object($post) || ! isset($post->ID) ) return;
    $postid = $post->ID;
  }
  $cats = wp_get_object_terms( $postid, 'product_cat', array('fields' => 'slugs') );
  $fields = array();
  if ( in_array( 'laptop', $cats ) ) // 'laptop' is a category slug
    $fields[] = array_merge($fields, array('cpu', 'ram', 'gpu');
  if ( in_array( 'hdd', $cats ) )
    $fields[] = array_merge($fields, array('capacity', 'rpm');
  if ( in_array( 'pc_parts', $cats ) )
    $fields[] = array_merge($fields, array('manufacturer');
  if ( in_array( 'warranted', $cats ) )
    $fields[] = array_merge($fields, array('warranty');
    ///.... and so on
  if ( ! empty($fields) ) {
    $out = '<ul>';
    foreach ( $fields as $field ) {
      $meta = get_post_meta( $postid, $field, TRUE );
      if ( ! empty ( $meta ) ) $out .= '<li>' . esc_html( $meta ) . '</li>';
    }
    $out = '</ul>';
    echo $out;
  }
}

After that, when inside the loop, somewhere after the_post() simply put:

my_product_fields();

When outside of the loop, to show the fields for a post, use

my_product_fields($postid);

If you want, to make function more flexible, you can put fields association with categories (all the lines like if ( in_array( 'cat_slug', $cats ) ) $fields[] = array_merge($fields, $array_of_cat_fields) ) in a separate file and require it from the function.