Conditional JSON serialization using C#

问题

I have a class that I serialize to JSON in C# and post to a RESTful web service. I have a requirment that if one field is filled out another field not be present. The service errors if both fields are serialized into the JSON object. My class looks like this:

    [DataContract(Name = "test-object")]
public class TestObject
{
    [DataMember(Name = "name")]
    public string Name { get; set; }

    // If string-value is not null or whitespace do not serialize bool-value
    [DataMember(Name = "bool-value")]
    public bool BoolValue { get; set; }

    // If string-value is null or whitespace do not serialize it
    [DataMember(Name = "string-value")]
    public string StringValue { get; set; }
}

As noted in the comments, if StringValue has a value don't put BoolValue in the JSON object. If StringValue is blank, don't put in StringValue but instead put in BoolValue.

I found how to do this with XML serialization, but cannot find a way this works with JSON serialization. Is there conditional JSON serialization on C#?

回答1:

It appears you are using the DataContractJsonSerializer. In that case, you can:

Disable direct serialization of your properties with the attribute [IgnoreDataMember].
Create proxy string and bool? properties for serialization that return null when they should not be serialized. These can be private.
Set [DataMember(EmitDefaultValue=false)] on these proxy properties to suppress output of nulls.

Thus:

[DataContract(Name = "test-object")]
public class TestObject
{
    [DataMember(Name = "name")]
    public string Name { get; set; }

    [IgnoreDataMember]
    public bool BoolValue { get; set; }

    [IgnoreDataMember]
    public string StringValue { get; set; }

    bool ShouldSerializeStringValue()
    {
        return !String.IsNullOrWhiteSpace(StringValue);
    }

    // If string-value is not null or whitespace do not serialize bool-value
    [DataMember(Name = "bool-value", EmitDefaultValue=false)]
    bool? SerializedBoolValue {
        get
        {
            if (!ShouldSerializeStringValue())
                return BoolValue;
            return null;
        }
        set
        {
            BoolValue = (value ?? false); // Or don't set it at all if value is null - your choice.
        }
    }

    // If string-value is null or whitespace do not serialize it
    [DataMember(Name = "string-value", EmitDefaultValue=false)]
    string SerializedStringValue {
        get
        {
            if (ShouldSerializeStringValue())
                return StringValue;
            return null;
        }
        set
        {
            StringValue = value;
        }
    }
}

Incidentally, this will also work with Json.NET, which respects data contract attributes.

来源：https://stackoverflow.com/questions/29173381/conditional-json-serialization-using-c-sharp

标签

json

serialization