Type Properties in XPO

• Jan 19, 2026

The following example illustrates how to implement Type Properties in an XPO persistent class.

private string dataTypeName;
[Browsable(false)]
[Persistent("DataType")]
public string DataTypeName {
    get { return dataTypeName; }
    set {
        Type type = XafTypesInfo.Instance.FindTypeInfo(value) == null ? null : 
            XafTypesInfo.Instance.FindTypeInfo(value).Type;
        if (_dataType != type) {
            _dataType = type;
        }
        //if (!IsLoading && value != dataTypeName) {

        //}
        SetPropertyValue<string>(nameof(DataTypeName), ref dataTypeName, value);
    }
}

private Type _dataType;
[TypeConverter(typeof(LocalizedClassInfoTypeConverter))]
[ImmediatePostData, NonPersistent]
public Type DataType {
    get { return _dataType; }
    set {
        if (_dataType != value) {
            _dataType = value;
            DataTypeName = (value == null) ? null : value.FullName;
        }
    }
}

Important

Do not use properties with Value Converters in criteria expressions executed on the database server side.

Value Converters change how the application saves and reads data in the database through special code in your application. However, the database does not recognize this special code. When a criterion is translated to a database query, a conversion implemented programmatically may not be applied or may be applied multiple times, leading to incorrect or unexpected results.