Json.net linq to json cast null to JObject throw exception

Question

For example, I write code like this

        bool hasCustomer = true;

        JObject j = JObject.FromObject(new
        {
            customer = hasCustomer? new
            {
                name = "mike",
                age = 48
            }:null
        });


        JObject c = (JObject)j["customer"];
        if (c != null)
            string name = (string) c["name"];

This works fine.

But if I set hasCustomer = false;

       JObject c = (JObject)j["customer"];

will throw an System.InValidCastException:

       Unable to cast object of type 'Newtonsoft.Json.Linq.JValue' to type 'Newtonsoft.Json.Linq.JObject'.

I was expecting should just assign null to JObject c since JObject is nullable.

So, what's the best way to handle something like this?

Pierluc SS · Accepted Answer · 2012-08-16 17:21:18Z

4

Ignoring null, seems to be producing the correct behavior.

    bool hasCustomer = false ;

    JsonSerializer s = new JsonSerializer() {
        NullValueHandling = NullValueHandling.Ignore
    };
    JObject j = JObject.FromObject( new {
        customer = hasCustomer ? new {
            name = "mike" ,
            age = 48
        } : null
    }, s );


    JObject c = (JObject)j[ "customer" ];

answered Aug 16, 2012 at 17:21

Pierluc SS

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Comments

Erhan A · Accepted Answer · 2012-08-16 17:19:48Z

-1

JObject can be nullable but this does not mean that JObject can cast null. You can try this :

JObject j = JObject.FromObject(new
        {
            customer = hasCustomer? new
            {
                name = "mike",
                age = 48
            }:new Object()
        });

edited Aug 16, 2012 at 17:19

answered Aug 16, 2012 at 17:12

Erhan A

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