Hi
in my case I wanted to add about 20 extra fields to each product. I follow this post and with help of the guys I managed to do it. Fields are visible in product details. Then I wanted to to make them visible in category overview (products listing) and make them also sortable like other fields(weight, price, manufacturer...) I managed to achive that. so if you managed to display those
extra fields in product details you are in half way. Now if you want do show those fields in product listing you must modify those files:
-includes/languages/english/index.php
standard fields:
define('TABLE_HEADING_QUANTITY', 'Quantity');
define('TABLE_HEADING_PRICE', 'Price');
define('TABLE_HEADING_WEIGHT', 'Weight');
define('TABLE_HEADING_BUY_NOW', 'Buy Now');
my new fields
define('TABLE_HEADING_NORMDIN', 'Norm DIN');
define('TABLE_HEADING_THREADSIZE', 'Thread size');
define('TABLE_HEADING_SIZEA', 'A mm');
define('TABLE_HEADING_SIZEB', 'B mm');
define('TABLE_HEADING_SIZEC', 'C mm');
define('TABLE_HEADING_SIZED', 'D mm');
-includes/modules/product_listing.php
you have to include your extra fields
similar to those standard
line about 20
case 'PRODUCT_LIST_MODEL':
$lc_text = TABLE_HEADING_MODEL;
$lc_align = '';
$zc_col_count_description++;
break;
case 'PRODUCT_LIST_NAME':
$lc_text = TABLE_HEADING_PRODUCTS;
$lc_align = '';
$zc_col_count_description++;
break;

and the same in line about 580
case 'PRODUCT_LIST_QUANTITY':
$lc_align = 'right';
$lc_text = $listing->fields['products_quantity'];
break;
case 'PRODUCT_LIST_WEIGHT':
$lc_align = 'right';
$lc_text = $listing->fields['products_weight'];
break;


case 'PRODUCT_LIST_NORMDIN':
if ($listing->fields['products_normdin']==0) {
//hide image column
$lc_text = '';
$lc_align = '';
} else {
//show image column
$lc_align = 'right';
$lc_text = $listing->fields['products_normdin'];
}
break;


case 'PRODUCT_LIST_THREADSIZE':
if ($listing->fields['products_threadsize']==0) {
//hide image column
$lc_text = '';
$lc_align = '';
} else {
//show image column
$lc_align = 'right';
$lc_text = $listing->fields['products_threadsize'];
}
break;
I got here extra condition if field is =0 field is not visible

includes/index_filters/default_filter.php

to add extra fields to sql querry like I did:

$listing_sql = "select " . $select_column_list . " p.products_id, p.products_type, p.manufacturers_id, p.products_price, p.products_tax_class_id, pd.products_description, IF(s.status = 1, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status = 1,
s.specials_new_products_price, p.products_price) as final_price, p.products_sort_order, p.product_is_call, p.product_is_always_free_shipping,
p.products_qty_box_status, p.products_normdin, p.products_threadsize, p.products_sizeA, p.products_sizeB, p.products_sizeC, p.products_sizeD,
p.products_sizeD1, p.products_sizeD2, p.products_sizeE, p.products_sizeE1, p.products_sizeF, p.products_sizeG, p.products_sizeH, p.products_sizeW, p.products_sizeX, p.products_sizeQG, p.products_sizeQX, p.products_peld, p.products_pelld, p.products_pehd, p.products_pa66, p.products_tpe,
p.products_peeva, p.products_pvc, p.products_pelldwasher, p.products_pa66oring, p.products_pelduvtreatment, p.products_injectedhole,
p.products_pa66washer, p.products_pehdwasher, p.products_pipethread, p.products_oldrefrence

there are 4 blocks with that querry in this file line from 28 to 105



and line 136
you can see standard fields and my new:
case 'PRODUCT_LIST_QUANTITY':
$listing_sql .= "p.products_quantity " . ($sort_order == 'd' ? 'desc' : '') . ", pd.products_name";
break;
case 'PRODUCT_LIST_IMAGE':
$listing_sql .= "pd.products_name";
break;
case 'PRODUCT_LIST_WEIGHT':
$listing_sql .= "p.products_weight " . ($sort_order == 'd' ? 'desc' : '') . ", pd.products_name";
break;

case 'PRODUCT_LIST_NORMDIN':
$listing_sql .= "p.products_normdin " . ($sort_order == 'd' ? 'desc' : '') . ", pd.products_name";
break;
case 'PRODUCT_LIST_THREADSIZE':
$listing_sql .= "p.products_threadsize " . ($sort_order == 'd' ? 'desc' : '') . ", pd.products_name";
break;
last file is:
includes/modules/pages/index/main_template_vars.php
line 138
$define_list = array('PRODUCT_LIST_MODEL' => PRODUCT_LIST_MODEL,
'PRODUCT_LIST_NAME' => PRODUCT_LIST_NAME,
'PRODUCT_LIST_MANUFACTURER' => PRODUCT_LIST_MANUFACTURER,
'PRODUCT_LIST_PRICE' => PRODUCT_LIST_PRICE,
'PRODUCT_LIST_QUANTITY' => PRODUCT_LIST_QUANTITY,
'PRODUCT_LIST_WEIGHT' => PRODUCT_LIST_WEIGHT,
'PRODUCT_LIST_NORMDIN' => PRODUCT_LIST_NORMDIN,
'PRODUCT_LIST_THREADSIZE' => PRODUCT_LIST_THREADSIZE,
'PRODUCT_LIST_SIZEA' => PRODUCT_LIST_SIZEA,
'PRODUCT_LIST_SIZEB' => PRODUCT_LIST_SIZEB,
'PRODUCT_LIST_SIZEC' => PRODUCT_LIST_SIZEC,
'PRODUCT_LIST_SIZED' => PRODUCT_LIST_SIZED,
'PRODUCT_LIST_SIZED1' => PRODUCT_LIST_SIZED1,
'PRODUCT_LIST_SIZED2' => PRODUCT_LIST_SIZED2,
'PRODUCT_LIST_SIZEE' => PRODUCT_LIST_SIZEE,
'PRODUCT_LIST_SIZEE1' => PRODUCT_LIST_SIZEE1,
'PRODUCT_LIST_SIZEF' => PRODUCT_LIST_SIZEF,
'PRODUCT_LIST_SIZEG' => PRODUCT_LIST_SIZEG,
'PRODUCT_LIST_SIZEH' => PRODUCT_LIST_SIZEH,
'PRODUCT_LIST_UVTREAT' => PRODUCT_LIST_UVTREAT,
'PRODUCT_LIST_INJECT' => PRODUCT_LIST_INJECT,
'PRODUCT_LIST_PA66WASH' => PRODUCT_LIST_PA66WASH,
'PRODUCT_LIST_PEHDWASH' => PRODUCT_LIST_PEHDWASH,
'PRODUCT_LIST_PIPETHREAD' => PRODUCT_LIST_PIPETHREAD,
'PRODUCT_LIST_IMAGE' => PRODUCT_LIST_IMAGE);

and line 190
case 'PRODUCT_LIST_MODEL':
$select_column_list .= 'p.products_model, ';
break;
case 'PRODUCT_LIST_NAME':
$select_column_list .= 'pd.products_name, ';
break;
case 'PRODUCT_LIST_MANUFACTURER':
$select_column_list .= 'm.manufacturers_name, ';
break;
case 'PRODUCT_LIST_QUANTITY':
$select_column_list .= 'p.products_quantity, ';
break;
case 'PRODUCT_LIST_IMAGE':
$select_column_list .= 'p.products_image, ';
break;
case 'PRODUCT_LIST_NORMDIN':
$select_column_list .= 'p.products_normdin, ';
break;
case 'PRODUCT_LIST_THREADSIZE':
$select_column_list .= 'p.products_threadsize, ';
break;
case 'PRODUCT_LIST_SIZEA':
$select_column_list .= 'p.products_sizeA, ';
break;
case 'PRODUCT_LIST_SIZEB':
$select_column_list .= 'p.products_sizeB, ';
break;
case 'PRODUCT_LIST_SIZEC':
$select_column_list .= 'p.products_sizeC, ';
break;
case 'PRODUCT_LIST_SIZED':
$select_column_list .= 'p.products_sizeD, ';
break;

once you take a closer look you gonne now how to do it