Web service - all products fields are set to default

[cdrrrrr]

Hello! I'm facing a situation regarding to the web service.

I've integrated a 3rd party applications (desktop based) to the online PrestaShop website, using web services. For the products resources, I only want to update the price and the available stock, using the relevant XML schema for each of the resources.

Item schema:

<?xml version="1.0" encoding="UTF-8" ?><prestashop><product><id /><id_supplier /><id_category_default /><new /><cache_default_attribute /><id_default_image /><id_default_combination /><id_tax_rules_group /><position_in_category /><type /><id_shop_default /><reference /><supplier_reference /><location /><width /><height /><depth /><weight /><quantity_discount /><ean13 /><upc /><cache_is_pack /><cache_has_attachments /><is_virtual /><on_sale /><online_only /><ecotax /><minimal_quantity /><price /><wholesale_price /><unity /><unit_price_ratio /><additional_shipping_cost /><customizable /><text_fields /><uploadable_files /><active /><redirect_type /><id_product_redirected /><available_for_order /><available_date /><condition /><show_price /><indexed /><visibility /><advanced_stock_management /><date_add /><date_upd /><pack_stock_type /><meta_description><language id="1" /></meta_description><meta_keywords><language id="1" /></meta_keywords><meta_title><language id="1" /></meta_title><link_rewrite><language id="1" /></link_rewrite><name><language id="1" /></name><description><language id="1" /></description><description_short><language id="1" /></description_short><available_now><language id="1" /></available_now><available_later><language id="1" /></available_later><associations><categories><category><id /></category></categories><images><image><id /></image></images><combinations><combination><id /></combination></combinations><product_option_values><product_option_value><id /></product_option_value></product_option_values><product_features><product_feature><id /><id_feature_value /> </product_feature></product_features><tags><tag><id /></tag></tags><stock_availables><stock_available><id /><id_product_attribute /> </stock_available></stock_availables><accessories><product><id /></product></accessories><product_bundle><product><id /><quantity /> </product></product_bundle> </associations> </product></prestashop>

 

Stock schema:

<?xml version="1.0" encoding="UTF-8" ?><prestashop><stock_available><id /><id_product /><id_product_attribute /><id_shop /><id_shop_group /><quantity /><depends_on_stock /><out_of_stock /> </stock_available></prestashop>

 

The issue I'm facing is the following: as I said, through the item schema, I'm updating only the price in PrestaShop which works fine. However, all the other values (picture, category etc.) are reset to default (the picture is gone, the category to which belongs to is gone). How should I do in order to upload only the price and every other information to remain as it is? Thanks