Conditional object serialization in JSON.NET

Question

I've been trying to figure out a way to ignore some objects from being serialized based on some conditions. All I can find is how to ignore properties of an object using the ShouldSerialize* method, but not how to ignore an entire object.

Here's an example that explains my situation. A company can have multiple employees, and the employees can be either current or non-current.

Public Class Company
    Public Property Name As String
    Public Property Employees As List(Of Employee)
End Class

Public Class Employee
    Public Property FirstName As List(Of Name)
    Public Property LastName As List(Of Name)
    Public Property Current As Boolean
End Class

I want to be able to ignore/exclude non-current employees from being serialized to json.

The only way I can think of right now is to separate current and non-current employees into two properties, so that I can just use the <JsonIgnoreAttribute()> for the non-current one.

Such as:

Public Class Company
    Public Property Name As String
    Public Property CurrentEmployees As List(Of Employee)
    <JsonIgnoreAttribute()>
    Public Property PastEmployees As List(Of Employee)
End Class

Public Class Employee
    Public Property FirstName As List(Of Name)
    Public Property LastName As List(Of Name)
    Public Property Current As Boolean
End Class

However I'm trying to avoid this since I have a number of these things in my real situation so I don't want to split up all lists into two that will require extensive code modification. Would be nice if it can be done just in the json serialization side.

Any help appreciated. Thanks!

Murugan · Accepted Answer · 2013-05-20 06:33:59Z

1

Json.Net supports conditional serialization. Check the below link for the implementation

http://james.newtonking.com/projects/json/help/html/ConditionalProperties.htm

answered May 20, 2013 at 6:33

Murugan

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Steven Manuel Over a year ago

I've seen that but it's not really what I'm after since it only lets me ignore the whole property if the condition is met. What I need is to be able to always include the property but not all the items within it.

Steven Manuel · Accepted Answer · 2013-12-18 23:17:40Z

0

There seems to be no built in functionality in Json.NET that allows me to achieve what is required. I ended up adding a function within the Company class that "cleans up" undesired data before being serialized into json.

Using the previous example:

Public Class Company
    Public Property Name As String
    Public Property Employees As List(Of Employee)

    ' Before serializing, call this function
    Public Function GetObjectToSerialize() As Company

        ' Clone the object
        Dim cleanObj As Company = CType(Me.MemberwiseClone, Company)

        If Me.Employees.Count > 0 Then
            cleanObj.Employees = New List(Of Employee)
            For Each empl As Employee In Me.Employees
                ' only include the current employees
                If Not empl.Current Then
                    cleanObj.Employees.Add(empl)
                End If
            Next
        End If
    End Function
End Class

Public Class Employee
    Public Property FirstName As List(Of Name)
    Public Property LastName As List(Of Name)
    Public Property Current As Boolean
End Class

All I have to do now is whenever I'm about to serialize a Company object, I call the GetObjectToSerialize() function and serialize the returned object instead.

Dim objToSave As Company = companyObj.GetObjectToSerialize()
Dim json As String = JsonConvert.SerializeObject(objToSave, Formatting.Indented)

answered Dec 18, 2013 at 23:17

Steven Manuel

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1 Comment

Panagiotis Kanavos Over a year ago

This isn't "conditional serialization", this is selectively cloning an object's members, then serializing the entire clone. You can do that easily with LINQ. I'd say the original question was misleading

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