CODEWITHSUNDEEP
c#json.net
daxu
daxu

Reputation: 4084

newton json default string value not working?

When I seralise an object, for some string properties, I would like to output empty string other than ignore or output null.

According to newton's doc, I could do this:

public class Data
{
    public int ProductId { get; set; }

    [DefaultValue("")]
    [JsonProperty(DefaultValueHandling = DefaultValueHandling.Include)]

    public string LargeData { get; set; }
}

However, in my test case, it still output null

Data D1 = new Data()
{
     ProductId = 1
};

var b = JsonConvert.SerializeObject(D1);

The output is {"ProductId":1,"LargeData":null}. Am I doing something wrong?

Upvotes: 2

Views: 369

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1502016

Looking at DefaultValueHandling it doesn't look like there's any way of doing what you want.

The default value attribute is only used when deserializing, if the property isn't specified in the JSON. The ignore / include choices are the ones which are relevant when serializing, and those don't affect the value that's serialized - just whether or not it should be serialized.

Unless you've got code which actually sets the value to null, the simplest option would be to make the property default to "" from a .NET perspective:

public class Data
{
    public int ProductId { get; set; }
    public string LargeData { get; set; } = "";
}

Upvotes: 4

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