C # - How to deserialize a generic <T> list when I don't know type (T)?

for auditory reasons, I keep the arguments of business methods serializable to the database using a binary format.

The problem is that when the argument is a general list, I do not find a way to drop the deserialized object, because I do not know the type, or if I know the type, which I do not know how to make the object at runtime.

Does anyone know how to distinguish an object containing a shared list dynamically at runtime?

I need to do this because I need to show deserialized data in the property grid:

object objArg = bformatter.Deserialize(memStr);

//If the type is a clr type (int, string, etc)
if (objArg.GetType().Module.Name == "mscorlib.dll")
{                 
    //If the type is a generic type (List<>, etc) 
    //(I'm only use List for these cases)
    if (objArg.GetType().IsGenericType)
    {
         // here is the problem
         pgArgsIn.SelectedObject = new { Value = objArg};                    

         //In the previous line I need to do something like... 
         //new { Value = (List<objArg.GetYpe()>) objArg};
     }
     else
     {
         pgArgsIn.SelectedObject = new { Value = objArg.ToString() };                    
     }
}
else
{
    //An entity object
    pgArgsIn.SelectedObject = objArg;                
}
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2 answers

BinaryFormatter ; ( , !). , . ( IList ..) . .

, PropertyGrid - object, , BinaryFormatter. , ? , IList ( ), IList<T>, , PropertyGrid !

, , T, ( ) - MakeGenericType() Activator.CreateInstance - .


OK; , - ; , , 2 ( "Fred" "Wilma" ) - , ; -p

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;

class Person
{
    public string Name { get; set; }
    public DateTime DateOfBirth { get; set; }

    public override string ToString() {
        return Name;
    }
}

static class Program
{
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Person fred = new Person();
        fred.Name = "Fred";
        fred.DateOfBirth = DateTime.Today.AddYears(-23);
        Person wilma = new Person();
        wilma.Name = "Wilma";
        wilma.DateOfBirth = DateTime.Today.AddYears(-20);

        ShowUnknownObject(fred, "Single object");
        List<Person> list = new List<Person>();
        list.Add(fred);
        list.Add(wilma);
        ShowUnknownObject(list, "List");
    }
    static void ShowUnknownObject(object obj, string caption)
    {
        using(Form form = new Form())
        using (PropertyGrid grid = new PropertyGrid())
        {
            form.Text = caption;
            grid.Dock = DockStyle.Fill;
            form.Controls.Add(grid);
            grid.SelectedObject = ListWrapper.Wrap(obj);
            Application.Run(form);
        }
    }
}

[TypeConverter(typeof(ListWrapperConverter))]
public class ListWrapper
{
    public static object Wrap(object obj)
    {
        IListSource ls = obj as IListSource;
        if (ls != null) obj = ls.GetList(); // list expansions

        IList list = obj as IList;
        return list == null ? obj : new ListWrapper(list);
    }
    private readonly IList list;
    private ListWrapper(IList list)
    {
        if (list == null) throw new ArgumentNullException("list");
        this.list = list;
    }
    internal class ListWrapperConverter : TypeConverter
    {
        public override bool GetPropertiesSupported(ITypeDescriptorContext context)
        {
            return true;
        }
        public override PropertyDescriptorCollection GetProperties(
            ITypeDescriptorContext context, object value, Attribute[] attributes) {
            return new PropertyDescriptorCollection(
                new PropertyDescriptor[] { new ListWrapperDescriptor(value as ListWrapper) });
        }
    }
    internal class ListWrapperDescriptor : PropertyDescriptor {
        private readonly ListWrapper wrapper;
        internal ListWrapperDescriptor(ListWrapper wrapper) : base("Wrapper", null)
        {
            if (wrapper == null) throw new ArgumentNullException("wrapper");
            this.wrapper = wrapper;
        }
        public override bool ShouldSerializeValue(object component) { return false; }
        public override void ResetValue(object component) {
            throw new NotSupportedException();
        }
        public override bool CanResetValue(object component) { return false; }
        public override bool IsReadOnly {get {return true;}}
        public override void SetValue(object component, object value) {
            throw new NotSupportedException();
        }
        public override object GetValue(object component) {
            return ((ListWrapper)component).list;
        }
        public override Type ComponentType {
            get { return typeof(ListWrapper); }
        }
        public override Type PropertyType {
            get { return wrapper.list.GetType(); }
        }
        public override string DisplayName {
            get {
                IList list = wrapper.list;
                if (list.Count == 0) return "Empty list";

                return "List of " + list.Count
                    + " " + list[0].GetType().Name;
            }
        }
    }
}
+3

- , T :

//during storage:
Type elementType = myList.GetType().GetGenericTypeDefinition().GetGenericArguments[0];
string typeNameToSave = elementType.FullName;

//during retrieval
string typeNameFromDatabase = GetTypeNameFromDB();
Type elementType = Type.GetType(typeNameFromDatabase);
Type listType = typeof(List<>).MakeGenericType(new Type[] { elementType });

listType, List<T>, (, List<Foo>). .

+2

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