NonSerialized on property

Question

When I write code like this

[XmlIgnore]
[NonSerialized]
public List<string> paramFiles { get; set; }

I get the following error:

Attribute 'NonSerialized' is not valid on this declaration type.
It is only valid on 'field' declarations.

If I write

[field: NonSerialized]

I get the following warning

'field' is not a valid attribute location for this declaration.
Valid attribute locations for this declaration are 'property'.
All attributes in this block will be ignored.

If I write

[property: NonSerialized]

I get the following error (again):

Attribute 'NonSerialized' is not valid on this declaration type.
It is only valid on 'field' declarations.

How can I use [NonSerialized] on a property?

Solution 1

Well... the first error says that you can't do that... from http://msdn.microsoft.com/en-us/library/system.nonserializedattribute.aspx

 [AttributeUsageAttribute(AttributeTargets.Field, Inherited = false)]
 [ComVisibleAttribute(true)]
 public sealed class NonSerializedAttribute : Attribute

I suggest using backing field

 public List<string> paramFiles { get { return list;}  set { list = value; } }
 [NonSerialized]
 private List<string> list;

Solution 2

Simple use:

[XmlIgnore]
[ScriptIgnore]
public List<string> paramFiles { get; set; }

Hopefully, it helps.

Solution 3

From C# 7.3 you may attach attributes to the backing field of auto-implemented properties.

Hence the following should work if you update your project's language to C# 7.3:

[field: NonSerialized]
public List<string> paramFiles { get; set; }

Solution 4

For those using JSON instead of XML you can use the [JsonIgnore] attribute on properties:

[JsonIgnore]
public List<string> paramFiles { get; set; }

Available in both Newtonsoft.Json and System.Text.Json (.NET Core 3.0).

Solution 5

As of .NET 3.0, you can use DataContract instead of Serializable. With the DataContract though, you will need to either "opt-in" by marking the serializable fields with the DataMember attribute; or "opt-out" using the IgnoreDataMember.

The main difference between opt-in vs opt-out is that opt-out by default will only serialize public members, while opt-in will only serialize the marked members (regardless of protection level).

View more solutions

Comments

[Ramon Zarazua B.]

Using the suggested backing field does not seem to work. The property is still being serialized.

[wiero]

Yes it works, but not in every class named AaaSerializer. Which serializer are you using?

[timmi4sa]

Indeed this even works in classic ASP.NET Web Service scenario by completely hiding the property name from the consumer (a great trick for those stuck in pre-WCF project)

[Setyo N]

The correct attribute is [NonSerialized], not [NonSerializable]

[drzaus]

oy...what if your "backing field" is a method?

[wiero]

Which serializer do you use?

[Kind Contributor]

NonSerialized will work for BinaryFormatter (at least) which serializes fields, and probably won't work for Json or XML serializers which serialize properties.

[Antonio Nicolaas Teyken]

I did not need to use [ScriptIgnore] to make this work

[General Grievance]

@AntonioNicolaasTeyken It depends on what you're using to serialize the data. In my case, [ScriptIgnore] prevented Json serialization.

[Mass Dot Net]

One more note: ScriptIgnoreAttribute is available in the System.Web.Script.Serialization namespace (MSDN).

[Min]

This should be re-marked as the best answer, because it's pretty awesome.

[Corey Alix]

Just to be clear, this works for binary serializer? Because the question already has XmlIgnore in the example so not sure how this can help.