How to ignore property conditionally during JSON serialization

Consider i have class Employer, i want serialize this class to json string and need ignore some properties conditionally. For ex: in my example, i want to include address1 and address2 only if it has valid values

  public class Employer

    {

 public int id { get; set; }

        public string name { get; set; }

       

 public string ssn { get; set; }

        public string address1 { get; set; }

        public string address2 { get; set; }

   }

Declare some values

Employer employer = new Employer(){ … address1 = "some value", address2 = null };

Now serialize it for json string

var jsonstring = JsonConvert.SerializeObject(employer,

                       Newtonsoft.Json.Formatting.None,

                       new JsonSerializerSettings

                       {

                           

                       });

Here you will get all the properties.

Now lets see how to ignore the properties conditionally, you can choose either one of these options.

Option 1: Use ShouldSerialize property inside class itself like below. But you need add individual shouldSerialize property for each class property.

  public class Employer

    {

 public int id { get; set; }

        public string name { get; set; }

       

 public string ssn { get; set; }

        public string address1 { get; set; }

        public string address2 { get; set; }

        public bool ShouldSerializeaddress1()

        {

            // don't serialize if it is null or empty or add any your custom conditions

            return !string.IsNullOrEmpty(address1);

        }

        public bool ShouldSerializeaddress2()

        {

            // don't serialize if it is null or empty or add any your custom conditions

            return !string.IsNullOrEmpty(address2);

        }

   }

Option 2: Instead creating multiple ShouldSerialize property inside class, we can create ContractResolver and add it in Json serialization as below,

Create Resolver Class,

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System.Linq;
using System.Reflection;
...

  public class EmployerShouldSerializeContractResolver : DefaultContractResolver

    {

        public new static readonly EmployerShouldSerializeContractResolver Instance = new EmployerShouldSerializeContractResolver();

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

        {

            JsonProperty property = base.CreateProperty(member, memberSerialization);

            if (property.DeclaringType == typeof(Employer))

            {

                property.ShouldSerialize =

                    instance =>

                    {

                        //ignore default values

                        return instance.GetType().GetProperty(member.Name).GetValue(instance, null) != property.DefaultValue;

                    };

            }

            return property;

        }

    }

Include it in JSON serialization,

var jsonstring = JsonConvert.SerializeObject(employer,

                       Newtonsoft.Json.Formatting.None,

                       new JsonSerializerSettings

                       {

                           ContractResolver = new EmployerShouldSerializeContractResolver()

                       });