Errata

Julie,
After spending some time getting the UnpaidReservations Defining Query to work as defined on pages 373-378 I almost gave up. I searched and found the updated edmx file that is included in the seperate download for chapter 14. After comparing and modifiying my edmx through the xml editor was I able to get the example to work.

The Chapter 14 copy of the BAModel.edmx had a couple of attributes that make the UnpaidReservations work.

The association mapping in the C-S for example should be

<AssociationSetMapping Name="ReservationUnpaidReservation" TypeName="BAModel.ReservationUnpaidReservation" StoreEntitySet="UnpaidReservations">
<EndProperty Name="UnpaidReservation">
<ScalarProperty Name="ID" ColumnName="ID" /></EndProperty>
<EndProperty Name="Reservation">
<ScalarProperty Name="ReservationID" ColumnName="ReservationID" />
</EndProperty>
<Condition ColumnName="ReservationID" IsNull="false"/>
</AssociationSetMapping>

The condition is critical

Another item is the Entity Type for the UnpaidReservation in the SSDL should be

<EntityType Name="UnpaidReservation" >
<Key>
<PropertyRef Name="ID" />
</Key>
<Property Name="ID" Type="int" Nullable="false" />
<Property Name="ReservationID" Type="int" Nullable="true" />
<Property Name="PaymentTotal" Type="money" Nullable="false" />
<Property Name="Cost" Type="money" Nullable="false" />
</EntityType>

There is also a subtle change in the DefiningQuery

<EntitySet Name="UnpaidReservations" EntityType="BreakAwayModel.Store.UnpaidReservation">
<DefiningQuery>

SELECT r.reservationid AS ID, SUM(amount) AS PaymentTotal,
MIN(events.[TripCostUSD]) AS cost,r.reservationID
FROM reservations r
JOIN payments p ON r.[ReservationID]=p.[ReservationID]
JOIN events ON r.[EventID]=events.[EventID]
GROUP BY r.[ReservationID]
HAVING SUM(amount)&lt;min(TripCostUSD)
UNION
SELECT r.reservationid, 0,MIN(events.[TripCostUSD]) AS cost,r.ReservationID
FROM reservations r
JOIN events ON r.[EventID]=events.[EventID]
WHERE r.[ReservationID] NOT IN (SELECT reservationID FROM payments)
GROUP BY r.[ReservationID]
</DefiningQuery>
</EntitySet>

I am not sure if I have listed all of the changes nessesary or in the correct order to correct the issues. Would it be possible to perhaps update the process in the errata so others can work the example.

I am enjoying the book and am impressed with the breadth of the subject matter. It must have been a bit like eating a whale to produce a book such as this one. I look forward to purchasing the next version with hopefully the EF V4 changes.

~Ian

On the bottom of page 80, you mention that the datatype for the contacts variable will show that it is a IQueryable of an "anonymous type". The type of the variable is actuall a System.Data.Objects.ObjectQuery of an "anonymous type". Of course, the ObjectQuery class implements IQueryable, but the correct type to show is System.Data.Objects.ObjectQuery


I love the book! Keep up the great work!

Bennie

It says: "Anonymous types are generally used for on-the-fly types that won’t be used elsewhere
in the application. You cannot even pass them from one method to another."

Maybe at the time you write this book, you couldn't pass an anonymous type from one method to another. But now you can if the receiving method receives a dynamic.

change

PEF.CreateQuery(Of DbDataRecord)(strQ)

to

Dim Contacts = context.CreateQuery(Of DbDataRecord)(strQ)

The author states that if you delete an Entity from a model and later wish to recreate it you can: 2)Delete the Entity from the model and then edit the XML and delete its EntitySet and EntityType. I found that you also have to delete any navigation associations with any other entity otherwise the Designer won't be able to display the model any more.

need to add the code to bind the customers data to the form:

customerBindingSource.DataSource = customers; // C# version

Run the form and edit one of the trips, changing a date and the loadging.

But before close the form, I think we have to click the save button.

The statement that ComboBox does not support updating is untrue: both SelectedValue and SelectedItem properties are two-way properties. In order to be useful for updating the related Location entity, one would rather bind to SelectedItem like this:

<ComboBox Name="comboBoxLodgingPartner" ... DisplayMemberPath="LodgingName" SelectedItem="{Binding ElementName=listBoxTrips, Path=SelectedItem.Lodging}" />

The assignment to SelectedValuePath can be dropped as well.

ObjectContext also has a pair of Changed and Changing events.

should be :

EntityObject also has a pair of [Paoperty]Changed and
[Paoperty]Changing events.

Dim custOnOtherEnd = CType(e.Element, Customer)

should be :

Dim contactOnOtherEnd = CType(e.Element, Contact)

and next page(264)

Partial Public Class Customer

should be :

Partial Public Class Contact

public Address()
{
this.CustomerReference.AssociationChanged +=
new CollectionChangedEventArgs(Add_CustRefChanged);
}

should be :

public Address()
{
this.CustomerReference.AssociationChanged +=
new CollectionChangedEventHandler(Add_ContactRefChanged);
}

and

private void Add_CustRefChanged(object sender,
CollectionChangeEventArgs e)
{
CollectionChangeAction act = e.Action;
Customer custOnOtherEnd = (Customer)e.Element;
//add your logic here
}

should be :

private void Add_ContactRefChanged(object sender,
CollectionChangeEventArgs e)
{
CollectionChangeAction act = e.Action;
Contact contactOnOtherEnd = (Contact)e.Element;
//add your logic here
}

and

public partial class Customer
{
public Customer()
{

should be :

public partial class Contact
{
public Contact()
{

An errata is already submitted for pg. 164. A second fix would be:

// Implementing AssiciationChanged
this.Contact.CustomerReference.AssociationChanged +=
new CollectionChangeEventHandler(CustomerReference_AssociationChanged);

and:

void CustomerReference_AssociationChanged(object sender, CollectionChangeEventArgs e)
{
CollectionChangeAction action = e.Action;
Customer customer = e.Element as Customer;
// Add logic here;
}

In Example 11-2, line 4 reads
'EntitySetName="Contacts" EntityTypeFilter="Customer"'
Setting EntityTypeFilter to Customer generates an error be cause it is not a type or derived type of EntitySet Contacts. Setting EntityTypeFilter to "Contact" or omitting it entirely removes the error condition.

On page 308 the lines
Imports BAGA.BreakAwayModel
and
using BAGA.BreakAwayModel;

should be
Imports BAGA
and
using BAGA;

On page 316 in the steps of creating the NonCustomer entity, there should be a mention that when one drags an entity from the toolbox to the design surface a property called "id" is created. This must be deleted prior to running the application or an exception noting a mapping error will be generated.

In the second paragraph giving instructions for creating the entity data model for the simple POCO example, there is this sentence:

"Name the EntityContainer POCOEntities and select all tables".

If all the the tables and subsequent directions are followed, the example won't run. If only the Contact and Address tables are selected for the model, then after following the subsequent directions, the example runs fine. Bringing in all the tables brings in many more navigation properties than are covered in the example.

GREAT book, by the way!

-Barry

The code is assumed to fix the two-way relation between Address and Contact. But when the address is re-linked to a different contact, for example by calling
address.Contact = contact1;
address.Contact = contact2;
both contacts will have the address listed and the object invariant is compromised.
This can be prevented by either checking for address._contact == null at the start of both Contact.AddAddress() and Address.set_Contact().

When using the download from Chapter 8 for the BreakAwayModel with this section of code I receive an error on context.SaveChanges():

The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value.

It appears that without setting:

newCust.AddDate = (some DateTime variable)
newCust.ModifiedDate = (another DateTime variable)

I receive this error because they were set as Nullable = false.

Ran into some glitches with the Deleting Reservations logic for the UpdateCustomer method.

The first is a small code error, the second is some weird databinding behavior.

First, in the WPF service UpdateCustomer method, the following is given for the portion of the method that deletes Reservations from the reservation delete list:

var resid = cust.ReservationsToDelete[0];

it should be:

var resid = cust.ReservationsToDelete[resi];

The former will only delete the first reservation in the list; the latter will delete multiple reservations in one call to UpdateCustomer.

Second, in the client, the DelRes_Click calls ShowReservations() to refresh the reservations list box. Works fine for comboBox1_SelectedIndexChanged and AddRes_Click. For some odd reason, when calllled from DelRes_Click, instead of diplaying reservation TripDetails, the listbox diaplys:

Chapter14ClientCS.BAWCFService.Reservation
Chapter14ClientCS.BAWCFService.Reservation
Chapter14ClientCS.BAWCFService.Reservation

- databinding's default behavior when it calls an object's ToString() method, and ToString() isn't overridden.

I fixed it by binding the listbox's DataSource property first, then binding ValueMember and DisplayMember:


listBox1.DataSource = _currentCustomer.Reservations;
listBox1.ValueMember = "ReservationID";
listBox1.DisplayMember = "TripDetails";

instead of:

listBox1.ValueMember = "ReservationID";
listBox1.DisplayMember = "TripDetails";
listBox1.DataSource = _currentCustomer.Reservations;

If anyone has an explanation for that one, I'd love to here it on this book's forum.

"This is why these extra entries exist - one for Contact, one for the related Trip, and one for the UnpaidReservtion entity (which you created in Chapter 13)."

It appears that only TWO extra entries exist. There isn't one for the UnpaidReservation entity.

It appears that the placeholder entries are only created in cases where the Reservation entity is on the 'Many' side of a relationship.

So there is a key into the Contacts and Trips entity sets, but not to the Payments or UnpaidReservations entity sets, where the Reservation entity is on the '1' or '1..0' side of the relationship.

I'm using the Chapter 14 version of the model.

Missing a cast.

EntityKey currRelEndA = relEntry.CurrentValue[0] as EntityKey;
EntityKey currRelEndB = relEntry.CurrentValue[1] as EntityKey;