Editing WoW:USERAPI GetSellValue

{{outdated|reason=The API now provides the sell value as part of [[API GetItemInfo]]()}}
{{userapi}}

The intent of this page is to provide a simple, consistent API for addons to query the vendor sell value of an item without the need to individually support every sell value addon in existence. All sell value addons are asked to provide the following global function:

 sellToVendorPrice = GetSellValue(item);

== Requirements ==
* 'item' must take the same values [[API GetItemInfo|GetItemInfo]] does
* Must return an int, or nil if unknown price. Only return 0 if you know the item cannot be sold to vendor.

== Recommended ==
Check for existence of the global before you define it and hook it if present. This allows for other sell value addons to provide prices that are not known by your addon.

== Example Code ==
The following code snippets illustrate how to create a hook capable of accepting the same input values as GetItemInfo.

=== Tekkub's version ===
This code will ensure that YourItemPriceFunc is passed an integer itemid, or the hooked function is called if present and your function does not return a value. It is optimized to take advantage of tail calls and avoid useless hook calls.
 local origGetSellValue = GetSellValue
 function GetSellValue(item)
 	local id = type(item) == "number" and item or type(item) == "string" and tonumber(item:match("item:(%d+)"))
 
 	if not id and type(item) == "string" then -- Convert item name to itemid, only works if the player has the item in his bags
 		local _, link = GetItemInfo(item)
 		id = link and tonumber(link:match("item:(%d+)")) 
 	end
 
 	return id and (YourItemPriceFunc(id) or origGetSellValue and origGetSellValue(id))
 end

=== Polarina's version ===
Functionally this is the same as Tekkub's version. Just slightly slower due to the extra select() call.
 '''local''' origGetSellValue = GetSellValue
 '''function''' GetSellValue(item)
 	'''local''' id, sellval
 	
 	'''if''' type(item) == "number" '''then'''
 		id = item
 	<b>else
 		</b>-- Acquire the second argument from GetItemInfo.<b>
 		local</b> link = select(2, GetItemInfo(item))
 		
 		-- Check if 'link' is set before using it.
 		id = link '''and''' tonumber(link:match("item:(%d+)"))
 	<b>end
 	
 	if</b> id '''then'''
 		sellval = -- Retrieve the price here...<b>
 	end
 	
 	</b>-- If 'sellval' is not set, fall back to origGetSellValue.<b>
 	return</b> sellval '''or''' (id '''and''' origGetSellValue '''and''' origGetSellValue(id))
 '''end'''

== Addons ==
This function is implemented by the following addons:
* [[Informant]] of the [[Auctioneer (AddOn)|Auctioneer]] [[AddOns]] Package by [http://auctioneeraddon.com/ The Auctioneer AddOns Team].
* [[User:Rowaasr13#My_addons|ItemDataCache]] (v1.11 and higher).
* [http://www.wowace.com/wiki/ItemPriceTooltip ItemPriceTooltip] by [[User:Bam|Bam]].
* [http://www.wowinterface.com/downloads/info7035-SellFish.html SellFish] by [[User:Tuller|Tuller]].
* [http://www.wowinterface.com/downloads/info7493-Valuation.html Valuation] by [[User:Polarina|Polarina]].
* [http://auctionator-addon.com Auctionator] by [[User:Zirco|Zirco]].
* [http://wow.curse.com/downloads/wow-addons/details/auctionlite.aspx AuctionLite] by Merial.

Addons using this function:
* [[VendorBait]] by [[User:Tekkub|Tekkub]]
* FuBar_GarbageFu

See also:
* [[GetAuctionBuyout]]