[Mono-bugs] [Bug 507120] New: GetListItemType throws NullReferenceException when dataSource's type is DataViewManager

[bugzilla_noreply at novell.com]

http://bugzilla.novell.com/show_bug.cgi?id=507120


           Summary: GetListItemType throws NullReferenceException when
                    dataSource's type is DataViewManager
    Classification: Mono
           Product: Mono: Class Libraries
           Version: 2.4.x
          Platform: i686
        OS/Version: openSUSE 11.1
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Windows.Forms
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: p.ricca at odyssee-ingenierie.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---


Created an attachment (id=294466)
 --> (http://bugzilla.novell.com/attachment.cgi?id=294466)
backtrace of debug mode

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.10)
Gecko/2009042700 SUSE/3.0.10-1.1.1 Firefox/3.0.10

Hello, 

In the function GetListItemType(object dataSource, string dataMember) of
System.Windows.Forms/ListBondingHelper.cs, our program crashed with
NullReferenceException, when dataSource's type is DataViewManager .
We had localized the piece of code where the Exception is thrown : 
if (dataSource is IEnumerable) {
    IEnumerator enumerator = ((IEnumerable) dataSource).GetEnumerator ();
    if (enumerator.MoveNext ()){
                'the execution goes here, and crahes
        return enumerator.Current.GetType (); ' (1)
    }

    if (dataSource is IList || dataSource.GetType () == typeof (IList<>)) {
        PropertyInfo property = GetPropertyByReflection (dataSource.GetType (),
"Item");
        return property.PropertyType; '(2)
    }
    // fallback to object
    return typeof (object);
}


After having tested, we found that it was because of enumerator.Current (1)
which is null. If we check before returning that enumerator.Current is not null
at (1) , we have another NullRefenceException at (2) because of property.

Finally, we have modified this piece of code by the following one : 
if (dataSource is IEnumerable) {
    IEnumerator enumerator = ((IEnumerable) dataSource).GetEnumerator ();
    if (enumerator.MoveNext ()){
        if (enumerator.Current != null)
            return enumerator.Current.GetType ();
    }
    if (dataSource is IList || dataSource.GetType () == typeof (IList<>)) {
        PropertyInfo property = GetPropertyByReflection (dataSource.GetType (),
"Item");
        if (property != null)
            return property.PropertyType;
    }
    // fallback to object
    return typeof (object);
}

If it can help you, you will find enclosed the backtrace of the debug mode.


Thank you in advance, do not hesitate to ask for precisions if necessary .

Reproducible: Always

Steps to Reproduce:
1.
2.
3.

-- 
Configure bugmail: http://bugzilla.novell.com/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.