question

Currently, limited edition items cannot be purchased directly with virtual currency, but you can grant items to the player via GrantItemsToUser. Then subtract the corresponding amount of virtual currency via SubtractUserVirtualCurrency. You can implement this function on Azure Function Cloud Script.

For the remaining number of limited edition items, you can get it via CheckLimitedEditionItemAvailability, you can also call this API on Azure Function Cloud Script.

You can refer to the code below.

// Azure Function Cloud Script
        [FunctionName("Test")]
        public static async Task<IActionResult> Test(
             [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
             ILogger log)
        {
            FunctionExecutionContext<dynamic> context = JsonConvert.DeserializeObject<FunctionExecutionContext<dynamic>>(await req.ReadAsStringAsync());
            var settings = new PlayFabApiSettings
            {
                TitleId = context.TitleAuthenticationContext.Id,
                DeveloperSecretKey = Environment.GetEnvironmentVariable("PLAYFAB_DEV_SECRET_KEY", EnvironmentVariableTarget.Process),
            };
            var authContext = new PlayFabAuthenticationContext
            {
                EntityToken = context.TitleAuthenticationContext.EntityToken
            };
            var serverApi=new PlayFabServerInstanceAPI(settings,authContext);
            var adminApi=new PlayFabAdminInstanceAPI(settings);

            string Itemid=context.FunctionArgument["Itemid"];
            string VCtype=context.FunctionArgument["VCtype"];
            int Price=context.FunctionArgument["Price"];

            var CheckLimitedEditionItemAvailabilityRequest=new CheckLimitedEditionItemAvailabilityRequest()
            {
                ItemId=Itemid
            };
            var result=await adminApi.CheckLimitedEditionItemAvailabilityAsync(CheckLimitedEditionItemAvailabilityRequest);
            if(result.Result.Amount<=0)
            {
                return new OkObjectResult(new{
                    message="No remaining."
                });
            };

            var GrantItemsToUserRequest=new GrantItemsToUserRequest()
            {
                ItemIds=new List<string>(){
                    Itemid
                },
                PlayFabId=context.CallerEntityProfile.Lineage.MasterPlayerAccountId
            };
            await serverApi.GrantItemsToUserAsync(GrantItemsToUserRequest);

            var SubtractUserVirtualCurrencyRequest=new PlayFab.ServerModels.SubtractUserVirtualCurrencyRequest()
            {
                Amount=Price,
                PlayFabId=context.CallerEntityProfile.Lineage.MasterPlayerAccountId,
                VirtualCurrency=VCtype
            };
            await serverApi.SubtractUserVirtualCurrencyAsync(SubtractUserVirtualCurrencyRequest);

            return null;
        } 

//Client
    public void Purchase()
    {
        PlayFabCloudScriptAPI.ExecuteFunction(new ExecuteFunctionRequest
        {
            FunctionName = "Test",
            FunctionParameter = new Dictionary<string, object>
            {
                {"Itemid"," " },
                {"VCtype"," " },
                {"Price",  }
            }
        },
        (result) =>
        {
            Debug.Log("Execute Success");
            Debug.Log(result.FunctionResult);
        },
        (error) =>
        {
            Debug.LogError(error.GenerateErrorReport());
        });
    }