How to not serialize an object based on a property's value?

Question

If the tags didn\'t give it away, I\'m working with C#\'s XmlSerializer class.

Say, for example, I have a Person class with various properties including age (int), name

Answer 1

If you have a list of Person objects and only want to serialise some of them, then just filter out the ones you don't need. For example:

List<Person> people = GetPeople(); //from somewhere
List<Person> filteredPeople = people.Where(p => !p.Deceased);

Now you only need to serialise filteredPeople.

Answer 2

Assuming that you have following type of Class structure(As you specified in the comment)

public class Person 
{
    public int Age { get; set; }

    public string Name { get; set; }

    public bool Deceased { get; set; }
}

public class Being
{
    public string Data { get; set; }

    [XmlElement("Human")]
    public Person Human { get; set; }

    public bool ShouldSerializeHuman()
    {
        return !this.Human.Deceased;
    }
}

Here I have added a method called ShouldSerialize this is called a pattern for XML serialization. Here you can use XmlArray and XmlArrayItem for lists etc.(With given name) then the ShouldSerialize checks if it can be serialized.

Below is the code I used for testing.

    private static void Main(string[] args)
    {
        var livingHuman = new Person() { Age = 1, Name = "John Doe", Deceased = true };
        var deadHuman = new Person() { Age = 1, Name = "John Doe", Deceased = false };

        XmlSerializer serializer = new XmlSerializer(typeof(Being));

        serializer.Serialize(Console.Out, new Being { Human = livingHuman, Data = "new" });

        serializer.Serialize(Console.Out, new Being { Human = deadHuman, Data = "old" });
    }

And here's the output:

=============================

Update:

If you have list of Person as Humans:

public class Being
{
    // [XmlAttribute]
    public string Data { get; set; }

    // Here add the following attributes to the property
    [XmlArray("Humans")]
    [XmlArrayItem("Human")]
    public List<Person> Humans { get; set; }

    public bool ShouldSerializeHumans()
    {
        this.Humans = this.Humans.Where(x => !x.Deceased).ToList();
        return true;
    }
}

Sample Test:

    private static void Main(string[] args)
    {
        var livingHuman = new Person() { Age = 1, Name = "John Doe", Deceased = true };
        var deadHuman = new Person() { Age = 1, Name = "John Doe", Deceased = false };

        var humans = new List<Person> { livingHuman, deadHuman };
        XmlSerializer serializer = new XmlSerializer(typeof(Being));

        serializer.Serialize(Console.Out, new Being() { Humans = humans, Data = "some other data" });
    }

Output: