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Item Restrictions & Requirements

This implements the following mechanic:

1. Key Values Table

First create a text file to write down your item properties. File Name, extension and path can be anything as long as the file structure is a proper table.

For this example, we will use this path: scripts/maps/item_info.kv

"item_name_here" //change it to a custom items
"levelRequired" "10"
"classRequired" "Warrior"

"levelRequired" "25"

To load a table into your game mode, you need to use the `LoadKeyValues( "path/to/file" ) lua function. This can be called at GameMode:InitGameMode() inside your main lua addon. GameMode = self

self.ItemInfoKV = LoadKeyValues( "scripts/maps/item_info.kv" ) 

If your table is badly formed (e.g. you missed a quotation mark or a bracket), this will fail and you'll get a lua console error when starting the game.

Note how I didn't add a "classRequired" to the 2nd item. When trying to access the GameMode.ItemInfoKV[itemNane].classRequired value will be nil, meaning there is no restriction on class (but still checks the level)

There are many ways to set a class, the most basic one is indexing .class in the hero handle the first time the hero is in game (using the barebones.lua default calls)

function GameMode:OnHeroInGame(hero)

if heroName == "npc_dota_hero_axe" then
hero.class = "Warrior"
print("Axe is ready!")


2. OnEquip Ability Event

Add this datadriven event on every item that needs to do a check for restrictions. It calls a lua script to do the logic check against the table.

This is needed because the listener for inventory changed is broken, and the Lua OnItemPickedUp event hook doesn't account for someone dragging an item into another players inventory.

"ScriptFile" "items.lua"
"Function" "ItemCheck"

3. Lua Script

In this example, I'll look for Level and Class requirements

Make use of the CustomError Flash UI by zedor to display a red error message when the item doesn't met any criteria found in the table.

There are some DeepPrintTable and print to check that the table is being reviewed as you expect.

function ItemCheck( event )
local itemName = event.ability:GetAbilityName()
local hero = EntIndexToHScript( event.caster_entindex )
local itemTable = GameMode.ItemInfoKV[itemName]
print("Checking Restrictions for "..itemName)

-- if there is no subtable for this item, end this script
if itemTable == nil then
return true

-- This timer is needed because OnEquip triggers before the item actually being in inventory
-- Go through every item slot
for itemSlot = 0, 5, 1 do
local Item = hero:GetItemInSlot( itemSlot )
-- When we find the item we want to check
if Item ~= nil and itemName == Item:GetName() then

-- Check Level Restriction
if itemTable.levelRequired then
print("Name","Level Req","Hero Level")
-- If the hero doesn't met the level required, show message and call DropItem
if itemTable.levelRequired > hero:GetLevel() then
FireGameEvent( 'custom_error_show', { player_ID = pID, _error = "You need level "..itemTable.levelRequired.." to use this." } )
DropItem(Item, hero)

-- Check Class Restriction
if itemTable.classRequired then
print("Name","Class Req","Hero Class")
-- If the item is for an specific class, message and drop
if itemTable.classRequired ~= hero.class then
FireGameEvent( 'custom_error_show', { player_ID = pID, _error = "Requires ".. hero.class .." to use." } )
DropItem(Item, hero)

function DropItem( item, hero )
-- Error Sound
EmitSoundOnClient("General.CastFail_InvalidTarget_Hero", hero:GetPlayerOwner())

-- Create a new empty item
local newItem = CreateItem( item:GetName(), nil, nil )
newItem:SetPurchaseTime( 0 )

-- This is needed if you are working with items with charges, uncomment it if so.
-- newItem:SetCurrentCharges( goldToDrop )

-- Make a new item and launch it near the hero
local spawnPoint = Vector( 0, 0, 0 )
spawnPoint = hero:GetAbsOrigin()
local drop = CreateItemOnPositionSync( spawnPoint, newItem )
newItem:LaunchLoot( false, 200, 0.75, spawnPoint + RandomVector( RandomFloat( 50, 150 ) ) )

--finally, remove the item

Leave your questions or suggestions below.