c# xml serialization doesn't write null

问题

when I serialize a c# object with a nullable DateTime in it, is there a way to leave the null value out of the xml file instead of having

 <EndDate d2p1:nil="true" xmlns:d2p1="http://www.w3.org/2001/XMLSchema-instance" />

回答1:

You can use the Specified extended property to leave out null values (or any other value, for that matter). Basically, create another property with the same name as the serialized property with the word Specified added to the end as a boolean. If the Specified property is true, then the property it is controlling is serialized. Otherwise, if it is false, the other property is left out of the xml file completely:

[XmlElement("EndDate")]
public DateTime? EndDate { get; set; }
[XmlIgnore]
public bool EndDateSpecified { get {
    return (EndDate != null && EndDate.HasValue); } }

回答2:

MSDN link

this allows you to say whether you want an empty element for null objects

回答3:

I know this is an old thread, but in case someone else find this:

You can also implement a public method for each property to check whether it should be serialized or not. The convention is:

bool ShouldSerialize[YourPropertyName]();

For example, in your case

public bool ShouldSerializeEndDate(){
    return (EndDate != null && EndDate.HasValue);
}

Do this for each property you want to optionally serialize.

来源：https://stackoverflow.com/questions/7636861/c-sharp-xml-serialization-doesnt-write-null