Ling To Entities Include Question

Hello,

I have 2 tables, Customer and Reservations. A Customer can have many reservations. I want to return a certain Customer based on his/her first, lastname and only return his/her reservations starting from within a certain date.

So i constructed next Linq to Entities query:

var q = from c in context.Contacts.OfType<Customer>().Include("Reservations")
where c.FirstName == p_firstName && c.LastName == p_lastName &&
c.Reservations.Any(r => r.ReservationDate >= p_reservationDate)
select c;

But this is not what i want, this query returns "all" reservations of the parametrized customer if any of the reservation dates is within the bounds of the given date (p_reservationDate).

What i want to do is only "eager" load those reservations made later or equal to the p_reservationDate.

In my opinion, it should be possible to add this clause in the "Include" method, like this:

<first_part_of_query>.Include("Reservations",c.Reservations.Any(r => r.ReservationDate >= p_reservationDate)).<final_party_of_query>

... but this does not work ...

so my question, how do we add conditions on the included child objects (in this case "Reservations").

Thx for any Response,

Emmanuel Nuyttens.

Wcf-wpf Implementation For Chap14

Hi Julie,

As chapter 14 lacks the WPF implementation, i've took the time to build the example on WPF, adding some features like DataTemplate for Reservations and combobox and a currency converter.

Implementation can be found in attached PDF.


greetz,

Emmanuel Nuyttens.

What About Huge Edmx Models ?

Hi Julie,

I have a little question concerning the edmx file and the designer. Most tutorials or books are using sample databases (like BreakAway, the one included in your book). Those db's only contain few tables (20 or less ...).

But what about "Big" production-related databases (like we have, they contain > 500 tabels), thus with many, many associations.

So, normally you have to work with a single edmx file (due to assosication retrievel & transactional correctnes), that's the most easy way, but putting +500 tabels in the designer, i don't think this will rock (IMG:https://forums.oreilly.com/style_emoticons/default/rolleyes.gif) , do you ?

I thought of 2 possible solutions, namely creating more then 1 context (thus more then one edmx file), but then you have to "group" tables with their dependencies (associations) together in a sole edmx file. By example, if i have an ordersystem with customer, supplier & orders, so ... i can make and edmx for customer & supplier related tables, and another one for the specific order tables.
... but what if i have next association:

Customer(0,1) -> CustomerType
Customer(0,*) -> Orders
Order(0,*) -> OrderDetails

So presume we've put "Customer" and "CustomerType" in one edmx, "Order" and "OrderDetails" in another. Problem is that Customer will only be aware of CustomerType, And Order of OrderDetails --> the association between Customer & Order is not known, as those tables "live" in a separate model.

Another solution i thought about was taking favour of the"Partial Class" implementation, so create model1.edmx with Customer & CustomerType and model2.edmx with "Order" and "OrderDetails", then in the code set both models to same partial class name, remove some redundant connection code in model2. This visually worked, i had 2 models pointing to the same partial class and different designer, but it didn't work out to add association between tables in the different models (IMG:https://forums.oreilly.com/style_emoticons/default/unsure.gif)

So, did someone @ MS think about this, or am i the sole one which is worried about this topic ?

thanx for any response,

Emmanuel Nuyttens

Troubels With Tpt Inheritance

Hi Julie,

Back again .... (IMG:https://forums.oreilly.com/style_emoticons/default/rolleyes.gif)

I saw some earlier post about "TPT mapping problems", i'm following your implementation for 12.2.1. Mapping TPT Inheritance, but ... after securly following your step by step explanation, i'm a bit into trouble, in other words ... get quit a few "compile errors", (others then the ones explained in the former post about TBT --> cfr. post by guy called BBrandon or so ...).

The error stack is quit long, i attached all errors in a PDF file. For each bunch of errors i display the XML on which the error points to ...

Hope you can help me. I like reading your book alot, but ... at this very moment i'm a bit disappointed that such a "minor" modification to the model (TPT inheritance between Customer & Contact) has such a bad impact to the model ...

Hope you can help me !

Greetz,

Emmanuel.

PS : For errors : see attached file (IMG:https://forums.oreilly.com/style_emoticons/default/wink.gif)

Customer Has No Direct Association To Address

Hi Julie,

Book mentioned :

public partial class Customer
{
public Customer()
{
this.Addresses.AssociationChanged +=
new CollectionChangeEventHandler(Addresses_AssociationChanged);
}
Private void Addresses_AssociationChanged
(object sender, CollectionChangeEventArgs e)
{
CollectionChangeAction act = e.Action;
Address addOnOtherEnd = (Address)e.Element;
//add your logic here
}
}

But assoc. to Address is in Contact, so former code should be :


public partial class Customer
{
public Customer()
{
this.Contact.Addresses.AssociationChanged += new System.ComponentModel.CollectionChangeEventHandler(Addresses_AssociationChanged)
;
}

void Addresses_AssociationChanged(object sender, System.ComponentModel.CollectionChangeEventArgs e)
{
...
}
}


Greetz,

Emmanuel.