Exclude property from serialization via custom attribute (json.net)

Question

I need to be able to control how/whether certain properties on a class are serialized. The simplest case is [ScriptIgnore]. However, I only want these attributes to be honored for this one specific serialization situation I am working on - if other modules downstream in the application also want to serialize these objects, none of these attributes should get in the way.

So my thought is to use a custom attribute MyAttribute on the properties, and initialize the specific instance of JsonSerializer with a hook that knows to look for that attribute.

At first glance, I don't see any of the available hook points in JSON.NET will provide the PropertyInfo for the current property to do such an inspection - only the property's value. Am I missing something? Or a better way to approach this?

Answer 1

Here's a generic reusable "ignore property" resolver based on the accepted answer:

/// <summary> /// Special JsonConvert resolver that allows you to ignore properties.  See https://stackoverflow.com/a/13588192/1037948 /// </summary> public class IgnorableSerializerContractResolver : DefaultContractResolver {     protected readonly Dictionary<Type, HashSet<string>> Ignores;      public IgnorableSerializerContractResolver() {         this.Ignores = new Dictionary<Type, HashSet<string>>();     }      /// <summary>     /// Explicitly ignore the given property(s) for the given type     /// </summary>     /// <param name="type"></param>     /// <param name="propertyName">one or more properties to ignore.  Leave empty to ignore the type entirely.</param>     public void Ignore(Type type, params string[] propertyName) {         // start bucket if DNE         if (!this.Ignores.ContainsKey(type)) this.Ignores[type] = new HashSet<string>();          foreach (var prop in propertyName) {             this.Ignores[type].Add(prop);         }     }      /// <summary>     /// Is the given property for the given type ignored?     /// </summary>     /// <param name="type"></param>     /// <param name="propertyName"></param>     /// <returns></returns>     public bool IsIgnored(Type type, string propertyName) {         if (!this.Ignores.ContainsKey(type)) return false;          // if no properties provided, ignore the type entirely         if (this.Ignores[type].Count == 0) return true;          return this.Ignores[type].Contains(propertyName);     }      /// <summary>     /// The decision logic goes here     /// </summary>     /// <param name="member"></param>     /// <param name="memberSerialization"></param>     /// <returns></returns>     protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization) {         JsonProperty property = base.CreateProperty(member, memberSerialization);          if (this.IsIgnored(property.DeclaringType, property.PropertyName)         // need to check basetype as well for EF -- @per comment by user576838         || this.IsIgnored(property.DeclaringType.BaseType, property.PropertyName)) {             property.ShouldSerialize = instance => { return false; };         }          return property;     } } 

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And usage:

var jsonResolver = new IgnorableSerializerContractResolver(); // ignore single property jsonResolver.Ignore(typeof(Company), "WebSites"); // ignore single datatype jsonResolver.Ignore(typeof(System.Data.Objects.DataClasses.EntityObject)); var jsonSettings = new JsonSerializerSettings() { ReferenceLoopHandling = ReferenceLoopHandling.Ignore, ContractResolver = jsonResolver }; 

Answer 2

Use the JsonIgnore attribute.

For example, to exclude Id:

public class Person {     [JsonIgnore]     public int Id { get; set; }     public string FirstName { get; set; }     public string LastName { get; set; } }