Checking if JValue is null

Question

Why this code doesn't run, I want to check if JSON contains integer for key PurchasedValue or not? () :

public PropertyInfo(Newtonsoft.Json.Linq.JToken jToken)
{
    this.jToken = jToken;
    int PurchasedValue = (int)(jToken["PurchasedValue"].Value ?? 0);
}

the error is :

Error CS0019: Operator `??' cannot be applied to operands of type `method group' and `int' (CS0019) 

Solution 1

From my understanding jToken["PurchasedValue"] is a nullable value. You have to use

int PurchasedValue = (int)(jToken["PurchasedValue"]?? 0);

nullableObj.Value can be only used without error only when there is a value for the nullableObj

Otherwise You can use like

int PurchasedValue = jToken["PurchasedValue"].HasValue?jToken["PurchasedValue"].Value: 0;

This May not even need type casting

Solution 2

You can compare the token type:

var purchasedValueToken = jToken["PurchasedValue"];
int purchasedValue = purchasedValueToken.Type == JTokenType.Null ? 0 : purchasedValueToken.Value<int>();

Solution 3

Well, there are couple of things here :

The jToken["PurchasedValue"] could return anything so a type check would be preferable.

You can change your code as following:

public PropertyInfo(Newtonsoft.Json.Linq.JToken jToken)
{
    this.jToken = jToken;
    int PurchasedValue = jToken["PurchasedValue"] is int ? jToken["PurchasedValue"] : 0;
}

Comments

[AVEbrahimi]

PurchasedValue = (int)(jToken["PurchasedValue"].Type!=JTokenType.Null ? jToken["PurchasedValue"].Value<int>(): 0);