Bulb Flash:- Azure Development Quick Tip!!

Recently we were stumped with the following error while working on an Azure project

Error 1 The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. C:\Program Files\MSBuild\Microsoft\Cloud Service\1.0\Visual Studio 10.0\Microsoft.CloudService.targets 202 5 OrderManagement

After a lot of head-banging, a simple Quick-Fix was to move the project to a root directory like a C: or a D: (Basically reduce the path of the project)

Hope you get to this quick-fix before you get to the head-banging

Cennest!

Bulb Flash:-SQL Azure tip; Firewall rules: allow all incoming IPs during testing and Development!

Before we even show you how , do note that this should be done only during testing of non-critical data which will cause no issues if accessed from unintended applications..

SQL Azure tracks the IP address for the purpose of security . However sometimes during development( and co-development) when you don’t have a static IP, it becomes quite a pain to keep checking the Firewall rules every time the app starts misbehaving…so during testing and development you can see the firewall rules to allow all connections by giving it the following settings..

 

Hope this saves you some time and headache…do remember to change these during production and when testing with critical data!

Until next time!

Cennest

Bulb Flash:- Some practical WPF MVVMLight tips!

One of our major projects recently used WPF 4.0 with MVVM pattern.We used the MVVM Light Toolkit for implementing the MVVM Pattern.

The MVVM Light Toolkit definitely has a lot to offer to make your life easier but the documentation is not exemplary!

Few things we learnt down the road as we came to a close on the project are

1. You are better off using the ViewModalLocator. We didn’t use it initially and realized that our ViewModels are not getting Disposed, multiple view models are getting created especially when using the “Commanding” feature!

2. When using Commands , if you are not using the ViewModalLocator, try not to set the IsDataSource property as it will change the DataContext of your screen to the new ViewModel and there will be inconsistency during commanding as previously set variables will not be available in the new VM. Or if you do need to set the IsDataSource property send all data needed by the command handler as arguments( because previously set data will not be available to the new VM)

3. You need a default empty constructor in all your ViewModels or your XAML screens commands won’t work(They instantiate the empty construtor)

4. You can pass event args parameters in commands using PassEventArgsToCommand="True" in your EventToCommand XAML

5. When using messaging use the method overload Send<TMessage>(TMessage message, object token).Using the token to register and send messages ensures it is delivered only to valid subscribers!

6. Every time you register for an event using the Messenger.Default.Register….ensure you Unregister also using the Messenger.Default.Unregister or else you might have memory leaks!!

Will try to write more elaborate posts detailing out these and more issues .Meanwhile drop a note at anshulee@cennest.com if you have any queries/ need more tips related to MVVM…

Until then!

Cennest!

EF 4.0 Bulb Flash!:- Load only what you need!!

A small tip for those working with Entity Framework 4.0:- We all know the concept of Lazy Loading in the Entity Framework: With lazy loading enabled, related objects are loaded when they are accessed through a navigation property.

With lazy loading a drawback is that an object retrieved from the database comes loaded with all its navigable Objects so you may be querying an “Order” class but it comes loaded with the Order.Customer object .

[Thanks to Julielerman for pointing out this inconsistency.  Lazy Loading loads related entities on Navigation and does not come “loaded” with them]

While you may want this in some cases, it makes sense to disable this feature in performance oriented applications and load only what you need!

As against what is written in MSDN , our experience is that when an entity context object gets created, its LazyLoadingEnabled property is defaulted to true!… This is also a reported issue with microsoft

So first step would be to disable the LazyLoadingEnabled!

ProgramEntities entityContext = new ProgramEntities();
entityContext.ContextOptions.LazyLoadingEnabled = false;

List<Order> orderList= entityContext.Orders.ToList();

Next, load what you need!

orderList.ForEach(p => entityContext.LoadProperty(p, "Customer"));

Now you can access the Customer as Order.Customer while ensuring you did not load other related  navigable properties like Order.Contents etc etc.

Hope this helps “lighten” up your code a bit!!

Cennest !!

Bulb Flash:-Returning Complex objects from Stored Procedures in Entity Framework!

Sometimes when using the Entity Framework we decide to encapsulate a complicated piece of SQL into a stored procedure and call it directly from your code.

But how to you extract the result of the Stored Proc if it returns a combination of columns from different tables?

Consider the following Stored Proc which returns a list clients recently worked on.

Notice that columns returned span 2 tables (Joined) so you can’t just make the SP return a List of Clients..

select top(@number)c.Client_Name as ClientName,c.ClientID asClientID,Max(p.EndTimeStamp) asLastTimeWorked
fromClients c joinTimeLog p
on
c.ClientID =p.ClientCode
Group Byc.Client_Name,c.ClientID
Order byMAX(p.EndTimeStamp)desc

So now you add the Stored Procedure in your Entity Diagram, but what will be its return type?

• If you double click the StoredProc in the Model.Store to get the following screen

• If your SP returns a combination of columns click on the “Get Column Information” button to get the column names returned by the SP

• Click on “Create new Complex Type” to create a new class for this group of columns

Now you can use the RecentClients_Results(Rename if you like) as a normal entity class in your code!

Hope this helps!

Until next time!

Cennest