The code in the download differs from the book for the RemoveItem() method in the last code block.

Unfortunately it turns out the neither the book code nor 2.0 download code provides the complete answer, because the eventing issue has a number of odd twists and turns based on whether you serialize your objects or not (through Clone() or using a remote data portal).

The current version: 2.1.4 (www.lhotka.net/cslanet/download.aspx) is pretty close, but even that has an issue with deserialized objects. I believe I have all of it correct now in what will become version 3.0.

The code in the book works if you never serialize objects.

But if you serialize/deserialize your objects then the automatic event handling provided by BindingList<T> gets lost, and so it is necessary to manually rehook those events and handle them properly. Somehow part of that code got into the download, though none of it is covered in Chapter 3 - so the errata is virtually impossible to work back into the book at this point :(

However, if you search through BusinessListBase for PropertyChanged you'll find where the events are hooked and where they are used. In RemoveItem() they must be unhooked, because there's no need to process the events from deleted objects.

If you look at 2.1.4 things are quite a bit different yet, because I'm being more proactive about checking to see if the child object implements INotifyPropertyChanged. In 2.0 I pre-suppose that to be true, but in 2.1+ I loosened the rules for what can be a child object, so that assumption was no longer true.

The only thing left, which I address in 3.0, is that the changed property's PropertyDescriptor should be passed up through the ListChanged event when it is raised. So in 3.0 there's now code to find and include the PropertyDescriptor. Here's a link to the current BLB class in the repository:

http://www.lhotka.net/cslacvs/viewvc.cgi/trunk/cslacs/Csla/BusinessListBase.cs?view=markup

The last line of the code block at the top of the page should read:

  _timestamp = (byte[])cm.Parameters["@newLastChanged"].Value;

In the second code block on the page, the second line from the bottom of the code reads:

  }""

It should read:

  }

On line 33 in the code block the line:

((Core.IEditableObject)value).CopyState();

should read:

((Core.IUndoableObject)value).CopyState();

In the first code block on the page, the first four lines should read:

CREATE PROCEDURE addAssignment
(
  @projectId uniqueidentifier,
  @resourceId int,

In the second paragraph under the Data Portal heading the first sentence should read:

As you'll see in Chapter 8, business objects will encapsulate data access logic within the objects.

In the code block there's a missing close bracket (}) in the set block, immediately before the else statement:

  }
}
else
  throw new ...

This bracket should be line 20 in the code listing.

The decision box "Parameters all null or type object?" directs to the wrong boxes.

Swap the "Yes" and "No" labels on the outbound arrows from the decision box.

The GetSwitchableRoot() method is incorrect, and should call DataPortal.Fetch. The code on the page is:

public static SwitchableObject GetSwitchableRoot(int id)
{
  return DataPortal.Create<SwitchableObject>(
    new RootCriteria(id));
}
 

public static SwitchableObject GetSwitchableRoot(int id)
{
  return DataPortal.Fetch<SwitchableObject>(
    new RootCriteria(id));
}

In the code at the end of the page, the finally block is missing a line and should read:

      finally

      {

        this.rolesBindingSource.RaiseListChangedEvents = true;

        this.rolesBindingSource.ResetBindings(false);

      }

The first few lines of the code block at the bottom of the page are incorrect. The proper way to tell data binding that you are done editing is to call EndEdit() on the binding source control, not to call ApplyEdit() manually.

The first 9 lines of the code in the book should be replaced by the following 10 lines:

    private void SaveButton_Click(object sender, EventArgs e)

    {

      this.rolesBindingSource.RaiseListChangedEvents = false;

      this.rolesBindingSource.EndEdit();

      try

      {

        Roles temp = _roles.Clone();

        _roles = temp.Save();

        this.Close();

      }

The first line in the code block at the bottom of the page is missing a (. It should read:

    public static DateTime StringToDate(string value)

In the code block at the top of the page, IsReadOnly is set to false twice. The second time it should be set to true:

IsReadOnly = true;

At the top of the page there is a "comment" in the HTML that is incorrect:

<%-- page content goes here --%>

This should be replaced by

<!-- page content goes here -->

In the code example at the top of the page, "If" should not be capitalized and the conditional is missing a close ")". The line should read:

      if (string.IsNullOrEmpty(((Customer)target).Name))

The Utilities.GetPropertyType() method has an incorrect check for Nullable<T>. The correct code in the code block in the middle of the page should be:

    public static Type GetPropertyType(Type propertyType)

    {

      Type type = propertyType;

      if (type.IsGenericType &&

        (type.GetGenericTypeDefinition() == typeof(Nullable<>)))

        return type.GetGenericArguments()[0];

      return type;

    }

Note the missing <> after the word Nullable on line 5.

The ObjectFieldInfo.Nullable() method has an incorrect check for Nullable<T>. The correct code at the top of the page should be:

        if (!t.IsValueType || _isNullable)

          return true;

        if (t.IsGenericType)

          return (t.GetGenericTypeDefinition() == typeof(Nullable<>));

        return false;

      }

    }

Note the missing <> after the word Nullable on line 4.

The addProject stored procedure (code block at the top of the page) has @description declared twice. Only the varchar(MAX) declaration should be present:

  @description varchar(MAX),

The updateProject stored procedure (code block at the bottom of the page) has @lastChanged declared twice. It should only be declared once:

  @lastChanged timestamp,

The Csla.Core.UndoableBase.AcceptChanges() method is missing a type check:

  foreach (FieldInfo field in fields)

  {

    // make sure we process only our variables

    if (field.DeclaringType == currentType)

    {

      // see if the field is undoable or not

      if (!NotUndoableField(field))

This check is present in CopyState() and UndoChanges(), but is missing from AcceptChanges().

(this errata does not affect the text or code shown in the book, but is a required change to the code download)

In the lower third of this page there's a Note with a reference to a URL with information about configuring session state in ASP.NET. The URL is misprinted. The text should read:

In the SaveProject() method in ProjectEdit, the resourcesBindingSource.DataSource property is set to null. This is incorrect, and the code should look like this:

  this.resourcesBindingSource.DataSource = this.projectBindingSource;

(this text is in the middle of the code shown on the page)

The SaveProject() method in ProjectEdit.aspx should catch the Csla.Validation.ValidationException and display details about the validation errors to the user. The SaveProject() method should look like this:

  private int SaveProject(Project project)

  {

    int rowsAffected;

    try

    {

      Session["currentObject"] = project.Save();

      rowsAffected = 1;

    }

    catch (Csla.Validation.ValidationException ex)

    {

      System.Text.StringBuilder message = new System.Text.StringBuilder();

      message.AppendFormat("{0}<br />", ex.Message);

      if (project.BrokenRulesCollection.Count == 1)

        message.AppendFormat("* {0}: {1}",

          project.BrokenRulesCollection[0].Property,

          project.BrokenRulesCollection[0].Description);

      else

        foreach (Csla.Validation.BrokenRule rule in project.BrokenRulesCollection)

          message.AppendFormat("* {0}: {1}<br />", rule.Property, rule.Description);

      this.ErrorLabel.Text = message.ToString();

      rowsAffected = 0;

    }

    catch (Csla.DataPortalException ex)

    {

      this.ErrorLabel.Text = ex.BusinessException.Message;

      rowsAffected = 0;

    }

    catch (Exception ex)

    {

      this.ErrorLabel.Text = ex.Message;

      rowsAffected = 0;

    }

    return rowsAffected;

  }

(this code replaces the first code shown on the page)