[This is the third in a series of posts on getting started with the new features in Entity Framework 4 based on the demos I did in my session at TechEd Europe in Berlin last week (Nov 2009).]

Entity Framework 4 relies significantly on the Text Template Transformation Toolkit (T4) to generate code from the EDM.

I thought it would be useful to show a really simple example of T4 in action which is nothing to do with Entity Framework.

In a Visual Studio 2008/2010 solution, add a new item of type Text Template:

Edit the “output extension=” pragma to generate a “.cs” file and add some C# code for a very simple class which has a single method TheAnswer which contains a single WriteLine. In the WriteLine use a T4 <#= #> block. <#= represents the start of a simple evaluation block, in this case the evaluation is to add 41+1:

NB: I am using the Tangible T4 editor to give me syntax highlighting and intellisense. You will need to add this into Visual Studio using the Extensions Manager.

Next build the project or click on Transform Templates in the Solution Explorer:

You will now see a new C# file in your project, SimpleTemaplate.cs:

In summary a T4 template is composed of:

• Blocks of text: text that simply is copied into the output file(s)
• Directives: meta information for the template such as “output extension=” enclosed in <#@ … #>
• Statements: code enclosed in <#...#>
• Expressions: code that is evaluated to a string <#= …#>

The above is pretty much the most basic example of T4 I could come up with. However there are plenty of other great resources on T4 out there. Oleg Sych has been heavily involved with T4 for many years and has many great posts. You may want to start with this tutorial done as a series of posts.

[This is the second in a series of posts on getting started with the new features in Entity Framework 4 based on the demos I did in my session at TechEd Europe in Berlin last week (Nov 2009).]

Code generation from the Entity Data Model (EDM) has changed significantly in version 4 of the Entity Framework. The product does retain a backwardly compatible model of code generation but also now includes T4 templates for code generation. This is a fantastic addition to the Entity Framework as many developers want to (easily) control the code generated from the EDM to meet their specific needs, which was very difficult to do in version 1 as it depended on the CodeDom. T4 gives us:

• Full control over the code generation from an EDM
• The ability for developers to easily customise the templates produced by Microsoft
• The ability for Microsoft to easily add additional templates in the future
• The ability for developers to easily share templates between projects, teams and companies

T4 was first introduced in Visual Studio 2008 and stands for Text Template Transformation Toolkit – a code generation tool similar in capabilities to the likes of CodeSmith.

T4 was largely overlooked in Visual Studio 2008, in the main because there was no real UI for T4. In general  I come across very very few developers who have heard of or understand the power of T4. However, now that the Entity Framework team (and the ASP.NET MVC team) have adopted T4 wholeheartedly I expect T4 will itself get the attention it deserves.

The EF team include a single T4 template in Beta 2 but add a further template in CTP2 for self tracking entities  (In Beta 1 they also had a singel template but added an additional two in the companion CTP1).

By default you are not using T4 if you add a new EDM or if you open a version 1 EDM. You need to enable T4 code gen for your EDM. You do this by right clicking on the EDM design surface and then add in the template(s).

In Beta 1 this was called (confusingly) Add New Artifact Generation Item:

In Beta 2 it is renamed to Add Code Generation Item:

This will display the available choices:

Beta 1 with CTP 1

Beta 2 with CTP 2

Once you have added a template you will notice that the Custom Tool generation for the EDM is now blank (It normally is the value EntityModelCodeGenerator):

In my case I have added the POCO Code Generator (which was available in CTP1 for Beta 1 and will reappear in a future CTP for Beta 2). My solution now contains two T4 files – one to generate the Object Context class and another responsible for the generation of a class (and C# file) per Entity in the EDM. Note that a single T4 template can generate several files:

If we take a brief look at the contents of SimpleModel.Context.tt:

We can see that the text wrapped inside <# #> is evaluated by T4 to ultimately generated the resulting C# files. The code outside is just text in the final output. This approach should feel very familiar to anyone who has developed web sites using classic ASP. For example, this section of SimpleModel.Types.tt:

generates the partial class code in the C# file Order.cs:

All pretty straightforward really – although a lot of “smarts” is contained within those .tt files! I will add a more general post on T4 shortly.

[This is the first in a series of posts on getting started with the new features in Entity Framework 4 based on the demos I did in my session at TechEd Europe in Berlin last week (Nov 2009). ]

When adding an Entity Data Model to a project you are given the option to:

• Generate the Model from an existing database (SQL Server, Oracle etc) or
• Start with an Empty Model and create your conceptual model (sometimes referred to as Application Model or Domain Model) first – adding new Entities and Associations between Entities.

Unfortunately in version one of the Entity Framework the button “Empty model” was one of those “buttons that should never be pressed” (Reference the Xmas episode of Dr Who). Put simply – it took you down a path to many, many issues which were best avoided and the recommendation in the v1 days was to never use it.

Fortunately in the betas of Entity Framework 4 things have got a lot better. You can now safely click on “Empty Model” and continue to sensibly create a working solution.

Hence, lets start with an Empty model.

Once you have your empty model you can add Entities and Associations by right clicking on the design surface:

Lets add two Entities – Category and Product, which you will likely be used to from the sample database Northwind. Once these are added we can then add a single association between Category and Product which is visualised in the design surface as the Navigation Properties on each Entity and the 1:Many association:

We now have a “finished” conceptual model but with no mapping to database tables. Interestingly there is no way to start to map Entities to tables until you do at least one “Generate Database from Model”:

Which gives you the Generate Database Script Wizard:

When you click Finish two things will happen.

• A DDL script will be written to the file system and will be included into the project. In this case ModelFirstModel.edmx.sql
• The Entity Data Model will be updated – a new mapping file and store schema file will be generated. Remember that the Entity Data Model (EDM) is made up of three schemas – Conceptual, Mapping and Store

You get the option to update the Entity Data Model or not – but TBH the only option is to go with Yes. The update of the EDM is 100% destructive:

Note the DDL script is not automatically run against your database. Which is a good thing as it is also 100% destructive:

Hence all that is then left to do is to actually execute the DDL script to create the database, which for me I tend to do inside SQL Server Management Studio. You will then see that the Entities and Associations are now mapped and you can begin to customise those mappings.

That has covered the simple stuff with Model First but I plan to revisit this topic in the near future and look at why and how you might use it in a real solution.

As I mentioned earlier this week, we now have a CTP release of a version of SSMS that is SQL Azure aware.

I thought it might be useful to share my first few minutes with it. First up, I cleared out my SQL Azure account using the portal (dropped all my databases).

And I made sure the firewall setting would allow me to connect: (for simplicity I just opened up everything. Don’t do that!)

Then I downloaded (155MB) SSMS R2 Nov CTP (32bit or 64bit) and installed it:

Which gave me a new menu group for R2:

Launching SSMS R2 I filled in my server name, admin name and password copied over from the portal:

Which then gave me the usual catalogue view:

And allowed me to do a Create Database using the new SQL Azure templates (no dialogue boxes):

Which was there waiting for me in the portal:

I have not done an exhaustive check – but looks like we have SQL Azure templates for most/all :-)

Nice and simple. I also just spotted a similar post – check that out as well.

Enjoy

Some pictures from the awesome TechEd Europe.

My favourite – “Xmas Lunch” on the Thursday:

The rather large entrance

The Berlin wall (outside a restaurant!)

The amazing hands on lab area:

A typical session (AJAX in this case):

The expo:

The community doodle wall:

I suspect Andrew Fryer was at work:

And a panel discussion:

I have had a bit of a “SQL Azure” day at TechEd Europe. I sat through David Robinsons excellent intro to SQL Azure development (smooth, on time, great Q&A), caught up with David afterwards to exchange stories on SQL Azure and find out what I will be missing at PDC next week and then grabbed the chance to capture a short 10minute podcast which I will publish up on Channel 9 next week.

David did his demos using a new version of SQL Server Management Studio which works with SQL Azure and announced that it would be publicly available today. And it is.

You can download SSMS in 32bit and 64bit flavours (Unfortunately I can not – as my hotel free internet is blocking it!)

• SQLManagementStudio_x86 Executable
• SQLManagementStudio_x64 Executable

These links are taken from the Microsoft® SQL Server® 2008 R2 November Community Technology Preview - Express Edition download page.

Also check out this "getting started post" of my first few minutes with SSMS.