Xml serialization - Hide null values

Question

When using a standard  NET Xml Serializer  is there any way I can hide all null values  The below is an example of the output of my class  I don t want to output the nullable integers if they are set to null   Current Xml output      lt  xml version  1 0  encoding  utf-8   gt   lt myClass gt      lt myNullableInt p2 nil  true  xmlns p2  http   www w3 org 2001 XMLSchema-instance    gt      lt myOtherInt gt -1 lt  myOtherInt gt   lt  myClass gt    What I want      lt  xml version  1 0  encoding  utf-8   gt   lt myClass gt      lt myOtherInt gt -1 lt  myOtherInt gt   lt  myClass gt

User · Accepted Answer

You can create a function with the pattern ShouldSerialize{PropertyName} which tells the XmlSerializer if it should serialize the member or not.

For example, if your class property is called MyNullableInt you could have

public bool ShouldSerializeMyNullableInt() 
{
  return MyNullableInt.HasValue;
}

Here is a full sample

public class Person
{
  public string Name {get;set;}
  public int? Age {get;set;}
  public bool ShouldSerializeAge()
  {
    return Age.HasValue;
  }
}

Serialized with the following code

Person thePerson = new Person(){Name="Chris"};
XmlSerializer xs = new XmlSerializer(typeof(Person));
StringWriter sw = new StringWriter();
xs.Serialize(sw, thePerson);

Results in the followng XML - Notice there is no Age

<Person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Name>Chris</Name>
</Person>

User · Answer

Additionally to what Chris Taylor wrote  if you have something serialized as an attribute  you can have a property on your class named  PropertyName Specified to control if it should be serialized  In code   public class MyClass        XmlAttribute      public int MyValue        XmlIgnore      public bool MyValueSpecified

User · Answer

private static string ToXml Person obj      XmlSerializerNamespaces namespaces   new XmlSerializerNamespaces      namespaces Add string Empty  string Empty      string retval   null    if  obj    null          StringBuilder sb   new StringBuilder        using  XmlWriter writer   XmlWriter Create sb  new XmlWriterSettings     OmitXmlDeclaration   true                 new XmlSerializer obj GetType    Serialize writer  obj namespaces             retval   sb ToString          return retval

User · Answer

It exists a property called XmlElementAttribute IsNullable   If the IsNullable property is set to true  the xsi nil attribute is generated for class members that have been set to a null reference    The following example shows a field with the XmlElementAttribute applied to it  and the IsNullable property set to false   public class MyClass       XmlElement IsNullable   false      public string Group      You can have a look to other XmlElementAttribute for changing names in serialization etc

User · Answer

You can define some default values and it prevents the fields from being serialized        XmlElement  DefaultValue          string data        XmlArray  DefaultValue null       List lt string gt  data

User · Answer

I prefer creating my own xml with no auto-generated tags  In this I can ignore creating the nodes with null values   public static string ConvertToXML lt T gt  T objectToConvert                XmlDocument doc   new XmlDocument            XmlNode root   doc CreateNode XmlNodeType Element  objectToConvert GetType   Name  string Empty           doc AppendChild root           XmlNode childNode           PropertyDescriptorCollection properties   TypeDescriptor GetProperties typeof T            foreach  PropertyDescriptor prop in properties                        if  prop GetValue objectToConvert     null                                childNode   doc CreateNode XmlNodeType Element  prop Name  string Empty                   childNode InnerText   prop GetValue objectToConvert  ToString                    root AppendChild childNode                                                return doc OuterXml

User · Answer

In my case the nullable variables elements were all String type  So  I simply performed a check and assigned them string Empty in case of NULL  This way I got rid of the unnecessary nil and xmlns attributes  p3 nil  true  xmlns p3  http   www w3 org 2001 XMLSchema-instance      Example   myNullableStringElement   varCarryingValue    string Empty     OR  myNullableStringElement   myNullableStringElement    string Empty

[c#] Xml serialization - Hide null values

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