How to sort catalog items by the price of trade offers (bitrix)?

Question

1C-Bitrix

There is a catalog with goods, each product can have a different number of trade offers when you click "sort by price", sorting should occur by the price of trade offers

Answer 1

There was a similar situation.
Used the old Bitrix code. You need to add the following code to the /bitrix/php_interface/init.php file:

/*Version 0.3 2011-04-25*/
AddEventHandler("iblock", "OnAfterIBlockElementUpdate", "DoIBlockAfterSave");
AddEventHandler("iblock", "OnAfterIBlockElementAdd", "DoIBlockAfterSave");
AddEventHandler("catalog", "OnPriceAdd", "DoIBlockAfterSave");
AddEventHandler("catalog", "OnPriceUpdate", "DoIBlockAfterSave");
function DoIBlockAfterSave($arg1, $arg2 = false)
{
 $ELEMENT_ID = false;
 $IBLOCK_ID = false;
 $OFFERS_IBLOCK_ID = false;
 $OFFERS_PROPERTY_ID = false;
 if (CModule::IncludeModule('currency'))
 $strDefaultCurrency = CCurrency::GetBaseCurrency();

 //Check for catalog event
 if(is_array($arg2) && $arg2["PRODUCT_ID"] > 0)
 {
 //Get iblock element
 $rsPriceElement = CIBlockElement::GetList(
 array(),
 array(
 "ID" => $arg2["PRODUCT_ID"],
 ),
 false,
 false,
 array("ID", "IBLOCK_ID")
 );
 if($arPriceElement = $rsPriceElement->Fetch())
 {
 $arCatalog = CCatalog::GetByID($arPriceElement["IBLOCK_ID"]);
 if(is_array($arCatalog))
 {
 //Check if it is offers iblock
 if($arCatalog["OFFERS"] == "Y")
 {
 //Find product element
 $rsElement = CIBlockElement::GetProperty(
 $arPriceElement["IBLOCK_ID"],
 $arPriceElement["ID"],
 "sort",
 "asc",
 array("ID" => $arCatalog["SKU_PROPERTY_ID"])
 );
 $arElement = $rsElement->Fetch();
 if($arElement && $arElement["VALUE"] > 0)
 {
 $ELEMENT_ID = $arElement["VALUE"];
 $IBLOCK_ID = $arCatalog["PRODUCT_IBLOCK_ID"];
 $OFFERS_IBLOCK_ID = $arCatalog["IBLOCK_ID"];
 $OFFERS_PROPERTY_ID = $arCatalog["SKU_PROPERTY_ID"];
 }
 }
 //or iblock which has offers
 elseif($arCatalog["OFFERS_IBLOCK_ID"] > 0)
 {
 $ELEMENT_ID = $arPriceElement["ID"];
 $IBLOCK_ID = $arPriceElement["IBLOCK_ID"];
 $OFFERS_IBLOCK_ID = $arCatalog["OFFERS_IBLOCK_ID"];
 $OFFERS_PROPERTY_ID = $arCatalog["OFFERS_PROPERTY_ID"];
 }
 //or it's regular catalog
 else
 {
 $ELEMENT_ID = $arPriceElement["ID"];
 $IBLOCK_ID = $arPriceElement["IBLOCK_ID"];
 $OFFERS_IBLOCK_ID = false;
 $OFFERS_PROPERTY_ID = false;
 }
 }
 }
 }
 //Check for iblock event
 elseif(is_array($arg1) && $arg1["ID"] > 0 && $arg1["IBLOCK_ID"] > 0)
 {
 //Check if iblock has offers
 $arOffers = CIBlockPriceTools::GetOffersIBlock($arg1["IBLOCK_ID"]);
 if(is_array($arOffers))
 {
 $ELEMENT_ID = $arg1["ID"];
 $IBLOCK_ID = $arg1["IBLOCK_ID"];
 $OFFERS_IBLOCK_ID = $arOffers["OFFERS_IBLOCK_ID"];
 $OFFERS_PROPERTY_ID = $arOffers["OFFERS_PROPERTY_ID"];
 }
 }

 if($ELEMENT_ID)
 {
 static $arPropCache = array();
 if(!array_key_exists($IBLOCK_ID, $arPropCache))
 {
 //Check for MINIMAL_PRICE property
 $rsProperty = CIBlockProperty::GetByID("MINIMUM_PRICE", $IBLOCK_ID);
 $arProperty = $rsProperty->Fetch();
 if($arProperty)
 $arPropCache[$IBLOCK_ID] = $arProperty["ID"];
 else
 $arPropCache[$IBLOCK_ID] = false;
 }

 if($arPropCache[$IBLOCK_ID])
 {
 //Compose elements filter
 if($OFFERS_IBLOCK_ID)
 {
 $rsOffers = CIBlockElement::GetList(
 array(),
 array(
 "IBLOCK_ID" => $OFFERS_IBLOCK_ID,
 "PROPERTY_".$OFFERS_PROPERTY_ID => $ELEMENT_ID,
 ),
 false,
 false,
 array("ID")
 );
 while($arOffer = $rsOffers->Fetch())
 $arProductID[] = $arOffer["ID"];

 if (!is_array($arProductID))
 $arProductID = array($ELEMENT_ID);
 }
 else
 $arProductID = array($ELEMENT_ID);

 $minPrice = false;
 $maxPrice = false;
 //Get prices
 $rsPrices = CPrice::GetList(
 array(),
 array(
 "PRODUCT_ID" => $arProductID,
 )
 );
 while($arPrice = $rsPrices->Fetch())
 {
 if (CModule::IncludeModule('currency') && $strDefaultCurrency != $arPrice['CURRENCY'])
 $arPrice["PRICE"] = CCurrencyRates::ConvertCurrency($arPrice["PRICE"], $arPrice["CURRENCY"], $strDefaultCurrency);

 $PRICE = $arPrice["PRICE"];

 if($minPrice === false || $minPrice > $PRICE)
 $minPrice = $PRICE;

 if($maxPrice === false || $maxPrice < $PRICE)
 $maxPrice = $PRICE;
 }

 //Save found minimal price into property
 if($minPrice !== false)
 {
 CIBlockElement::SetPropertyValuesEx(
 $ELEMENT_ID,
 $IBLOCK_ID,
 array(
 "MINIMUM_PRICE" => $minPrice,
 "MAXIMUM_PRICE" => $maxPrice,
 )
 );
 }
 }
 }
}

You will have two product properties: Minimum Price and Maximum Price. In order for these fields to have data, you need to go to the product card and click Save, or they will be filled in when creating a new product with trade offers.
Then you do the standard code sorting by these two properties in the section.php of the Catalog complex component and display it visually in the section.php template of the same component. Read about creating sorting in Bitrix e. That's all.