Passing int list as a parameter to a web user control

Question

I want to pass an int list (List) as a declarative property to a web user control like this:

Answer 1

I believe the problem is the set{}. The type converter want to change the List<int> back into a string, but CanConvertFrom() fails for List<int>.

Answer 2

You can pass it into a string and split on comma to populate a private variable. Does not have the nicety of attribution, but will work.

private List<int> modules;
public string ModuleIds
{
  set{
    if (!string.IsNullOrEmpty(value))
    {
    if (modules == null) modules = new List<int>();
    var ids = value.Split(new []{','});
    if (ids.Length>0)
      foreach (var id in ids)
        modules.Add((int.Parse(id)));
    }
}

Answer 3

WHile I can't say I have any particular experience with this error, other sources indicate that you need to add a conversion to the type InstanceDescriptor. check out:

http://weblogs.asp.net/bleroy/archive/2005/04/28/405013.aspx

Which provides an explanation of the reasons or alternatively:

http://forums.asp.net/p/1191839/2052438.aspx#2052438

Which provides example code similar to yours.

Answer 4

pass the list from the code behind...

aspx:

<UC:MyControl id="uc" runat="server" />

code-behind:

List<int> list = new List<int>();
list.add(1);
list.add(2);
list.add(3);

uc.ModuleIds = list;

Answer 5

The way I normally do this is to make the property wrap the ViewState collection. Your way looks better if it can be made to work, but this will get the job done:

public IList<int> ModuleIds
{
   get
   {
       string moduleIds = Convert.ToString(ViewState["ModuleIds"])

       IList<int> list = new Collection<int>();

       foreach(string moduleId in moduleIds.split(","))
       {
          list.Add(Convert.ToInt32(moduleId));
       }

      return list;
   }
}

Answer 6

I think that you're best option is to make your usercontrol have a DataSource-style property.

You take the property as an object and then do some type checking against IList/ IEnumerable/ etc to make sure that it is correct.