DataGrid not populating from CslaDataProvider

decius posted on Thursday, June 11, 2009

I must be missing something, but I don't know what. I have my csla dataprovider:

<csla:CslaDataProvider x:Key="ProcCodeListDataProvider"

FactoryMethod="BeginGetMyList"

ObjectType="SlTest.Library.MyList, SlTest.Library"

IsInitialLoadEnabled="False" >

</csla:CslaDataProvider>

----------------------------------------------------------

On a button click, I do this (

private void btnSubmit_Click(object sender, RoutedEventArgs e)

procCodeListProvider.FactoryParameters.Add(this.DataContext as CodeListCrit);

decius replied on Thursday, June 11, 2009

On thing has certainly helped me troubleshoot.  Let this be a lesson to any other Silverlight newbs:

I hadn't yet  subscribed to the CslaDataProvider DataChanged event like so:

private void CslaDataProvider_DataChanged(object sender, System.EventArgs e)

CslaDataProvider provider = (CslaDataProvider)(this.Resources["MyCslaDataProvider"]);

if (provider.Error != null)

System.Windows.Browser.HtmlPage.Window.Alert(provider.Error.Message);

Once the framework gets done with the async call for the BO fired from provider.Refresh() in the button click event is when it actually gets data in the provider.Data property (because of how Csla.Silverlight works with the wcf).

Now... I must figure out why I'm getting a "A parameterless constructor was not found for the object."  I thought I took care of this with my SILVERLIGHT comilation symbols. Must the constructor on the Server need to be public as well for Silverlight?? or is it something else.

esaulsberry replied on Thursday, June 11, 2009

decius:

procCodeListProvider.FactoryParameters.Add(this.DataContext as CodeListCrit);

Maybe I'm missing something but it seems odd to me you'd be passing the data context of the control as the factory criteria. 

You want to make sure any custom criteria classes have public parameterless constructors.

One way to debug binding is to include a value converter that doesn't do anything but give you a place to break. 

/// <summary>

/// This class exists to aid debugging. By attaching this converter to a binding, you can

/// set a break point as the object is bound and inspect it.

/// </summary>

public class DebugConverter : IValueConverter

#region IValueConverter Members

public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

Debug.WriteLine(value.ToString());

return value;

public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

Debug.WriteLine(value.ToString());

return value;

decius replied on Friday, June 12, 2009

esaulsberry:

Maybe I'm missing something but it seems odd to me you'd be passing the data context of the control as the factory criteria. 

I'm a newb to Silverlight and XAML.  This seemed to make sense to me, but I don't doubt that it could be odd.  In the past with Csla, I've always made my own public criteria classes extended from BusinessBase to use as the factory method's parameters.  That way I can bind that one class to the UI and perform validation on it from Business base etc, which has made for easy maintenance.  So here, that's what I'm trying to do (I set the datacontext of the control as the criteria, then fetch the data with it and bind that result to the DataGrid).  Is there a better (or more conventional) way to do this in Silverlight/XAML?? I'm so used to working with BindingSources that I'm really out of my element now.

That debug converter trick will be extremely handy! Thanks so much for that tip

esaulsberry replied on Friday, June 12, 2009

A couple of things might help:

My CslaDataProviders are usually set to not load automatically (IsInitialLoadEnabled="False").  In code I load criteria parameters.  For example, this code is called when the form is loaded.

_siteListProvider.FactoryParameters.Clear();
_siteListProvider.FactoryParameters.Add(App.ClientId);
_siteListProvider.FactoryParameters.Add("All Sites");
_siteListProvider.Refresh();

In my case, SingleCriteria frequently doesn't help for me.  I usually have to pass a client ID plus some other value.  I wrote a generic criteria class to support this.  The corresponding criteria class looks like this:

/// <summary>
/// A generic class to pass criteria containing the client id plus some other criteria value.
/// </summary>
/// <typeparam name="B">The type of the business class using the criteria.</typeparam>
/// <typeparam name="T">The type of the "other" criteria value.</typeparam>
/// <example>portal.BeginFetch(new ClientIdValueCriteria<ParentSiteNVL, string>(clientId, noSelectionLabel));</example>

[Serializable()]
public class ClientIdValueCriteria<B, T>:CriteriaBase
{
private int _clientId;
public int ClientId { get { return _clientId; } set { _clientId = value; } }

private T _value;
public T Value { get { return _value; } set { _value = value; } }

/// <summary>
/// Silverlight likes a empty public constructor.
/// </summary>

public ClientIdValueCriteria() : base(typeof(B)) { }

/// <summary>
/// Creates a new criteria class.
/// </summary>
/// <param name="clientId">The client id for this instance.</param>
/// <param name="value">The value of the non-clientid criteria.</param>

public ClientIdValueCriteria(int clientId, T value)
: base(typeof(B))
{
_clientId = clientId;
_value = value;
}

protected override void OnGetState(Csla.Serialization.Mobile.SerializationInfo info, StateMode mode)
{
info.AddValue("_clientId", _clientId);
info.AddValue("_value", _value);
base.OnGetState(info, mode);
}

protected override void OnSetState(Csla.Serialization.Mobile.SerializationInfo info, StateMode mode)
{
_clientId = (int)info.Values["_clientId"].Value;
_value = (T)info.Values["_value"].Value;
base.OnSetState(info, mode);
}

}

Here is the business class, in this case a name value list.

Fintanv replied on Friday, June 12, 2009