Serialize nullable type to optional non-nillable element

Question

I have an xsd schema with an optional element (minOccurs=0, maxOccurs=1) of type int. The element is NOT defined as nillable. In the d

Answer 1

I also encountered with this problem some time ago. I solved it by introducing additional property that handles serialization logic.

1. Firstly you mark your original property with [XmlIgnore] attribute to exlude it from serialization/deserialization.

   // Mark your original property from serialization/deserialization logic
   [XmlIgnore]
   public int? OriginalProperty { get; set; }
   

2. Then add the additional property and mark it with [XmlElement("YourElementName")] attribute to handle serialization logic.

   // Move serialization logic to additional string property
   [XmlElement("OriginalPropertyXmlElement")]
   public string OriginalPropertyAsString
   {
       get
       {
           //...
       }
       set
       {
           //...
       }
   }
   

3. On deserialization it will:

   set
   {
       // Check the field existence in xml
       if (string.IsNullOrEmpty(value))
       {
           // Set the original property to null
           this.OriginalProperty = default(int?);
       }
       else
       {
           // Get value from xml field
           this.OriginalProperty = int.Parse(value);
       }
   }
   

4. On serialization:

   get
   {
       if (this.OriginalProperty.HasValue)
       {
           // Serialize it
           return this.OriginalProperty.ToString();
       }
       else
       {
           // Don't serialize it
           return null;
       }
   }
   

5. The example could look like:

   [XmlRoot("scene")]
   public class Scene
   {
       [XmlIgnore]
       public int? ParentId { get; set; }
   
       [XmlElement("parent_id")]
       public string ParentIdAsString
       {
           get
           {
               return this.ParentId.HasValue ? this.ParentId.ToString() : null;
           }
   
           set
           {
               this.ParentId = !string.IsNullOrEmpty(value) ? int.Parse(value) : default(int?);
           }
       }
   }
   

It's pretty simple and you don't have to write your own serializer nor hacking xsd nor other stuff.