Tag archive for 't4'

14
Sep

LINQ to SQL template for Visual Studio 2008

By Damien Guard Categories: .NET Tags: , .

The latest update to my template for generating LINQ to SQL classes from DBML is now available.

If you want to customize the LINQ to SQL code generation phase in your project without additional tool dependencies this could be what you’re looking for.

23 Sep 2008 fixed stored procedures with 0 parameters
22 Sep 2008 fixed VB.NET IsForeignKey attribute for associations
18 Sep 2008 now generates stored procedures including insert/update/delete with concurrency checking.
14 Sep 2008 fixes for column mapping defaults, enum parsing, datacontext base type and now generates stored procedure methods.

New in this version

  • Inheritance - generates subclasses with all properties and code mappings.
  • VB.NET - CSharpDataContext.tt is joined by a VB.NET emitting VBNetDataContext.tt.
  • DataContract SP1 – additional mode to emit SP1-compatible DataContract serialization via Roger Jennings.
  • Composite keys – both as the primary key and as a foreign key in an association.
  • Type attributes – the data context and entity types can now be sealed or abstract as well as public, private, protected, internal or protected internal.
  • Associations – prevents foreign key values changing once the object association is made and updates parent side of one-to-many associations.
  • Stored procedures – generates method wrappers and associated methods to facilitate insert/update/delete with concurrency support.

Functionality compared to designer

A primary goal in developing the template was to allow for easy switching between the template and the LINQ to SQL designer so things are very similar.

Missing

  • Comprehensive sanity checking on the DBML.
  • The Custom Tool Namespace and project namespaces are not pulled in when the DBML namespaces not specified.

Fixed

The designer has a few bugs which helpfully this template doesn’t suffer from.

  • Modifying a table via a stored procedure using original values for concurrency will throw ChangeConflictException and not silently fail.
  • Protected internal virtual property doesn’t forget to be virtual.
  • Checks all associations based on a foreign key are not loaded before allowing change and not just the first one.

Improved

  • Fully customizable with full source.
  • Serialization mode to support DataContract improvements in .NET 3.5 SP1
    To use uncomment the line // data.Serialization = SerializationMode.DataContractSP1; in xDataClasses.tt
  • CanBeNull attribute generated for value types (useful when working with metadata).

Source compared to designer

The designer generated code can be difficult to read and isn’t well suited to template generation so the output from this template is different in a number of ways:

Sequence

Everything related to a column mapping – the storage variable, event signatures, attribute and the property itself – is batched together so it can be hit with a single loop making the template shorter and easier to work with.

#regions

Opinion may be divided on the usefulness of #regions in your own code but for code generation of large files I found it invaluable. There are regions for the logical parts of the data context and within each entity such as construction, column mapping, associations and serialization.

Style

The code generated should be a little easier to follow – if/else ordering, no redundant casts or extra brackets etc.

Namespace

I don’t believe adding “this” everywhere or fully qualifying attributes and exceptions makes things easy to read. I realize this might cause some name conflicts for some people but it is easy to change yourself and means the code is shorter and easier to work with for the majority.

Getting started

Although I work on the LINQ to SQL team this template should be treated as a third-party sample and is not supported by Microsoft.

Download LINQ to SQL for T4 v0.72 (12 KB)

  1. Add the L2ST4.tt and either CSharpDataContext.tt or VBNetDataContext.tt to your project
  2. Rename the xDataContext.tt to match your DBML file but with .tt extension instead of .dbml
  3. Set the Build Action to None for both the DBML file and for L2ST4.tt

Note that the template will only regenerate when it has been changed so use Run Custom Tool from the template’s right-mouse button menu in Solution Explorer when you’ve changed the DBML.

If you wish to switch back to using the designer code then set the DataContext.tt Build Action to None and the .dbml file Build Action to Compile.

Customization

The template runtime built into Visual Studio 2008 is called T4 and requires no additional tools however if you do a lot of editing you might want to install the Clarius T4 Editor for syntax highlighting and also check out the treasure trove of T4 material that is Oleg Sych’s blog.

The template is simple to follow, it loads the DBML file as an XML document then uses LINQ to XML to instantiate wrapper objects over the elements. This gives you a simple way to change default naming and behavior while making the template simpler to work with.

Let me know how you get on by leaving a comment here.

[)amien

13 Comments
23
Jul

LINQ to SQL T4 template reloaded

By Damien Guard Categories: .NET Tags: , .

A newer version of this LINQ to SQL template is available.

The topic of modifying the code generation phase of LINQ to SQL comes up quite often and the limited T4 template I published here last month was good at showing the potential but wasn’t a practical replacement for the code generation phase.

I am please to make available the next version, which now…

  • Runs from the DBML therefore keeping the designer in the loop
  • Generate all the attributes for columns and tables including UpdateCheck, IsDbGenerated etc.
  • Supports associations including those with a foreign key
  • Generates appropriate attributes and code for both serialization modes

In short it generates code that is now functionally equivalent to SQL Metal with the following caveats:

  • C# only – VB.NET can be added if there is some interest
  • Stored procedures – not yet supported
  • Table inheritance - incomplete
  • DBML changes require you open and re-save the T4 template so it regenerates the code
  • Unidirectional serialization requires you add System.Runtime.Serialization to your project references (thanks Roger!)

Download LINQ-to-SQL-T4-0.3.zip (5 KB)

To use the template :

  • Extract the archive and add the two files to your project
  • Right-click on the L2ST4.tt file, choose Properties and set the Custom Tool to blank
  • Rename DataClasses1.tt to the same name as your DBML file (but keeping the .tt extension) and open it
  • Click save and watch a freshly generate C# DataContext pop out
  • Switch off the LINQ to SQL designer generated C# by either setting the Custom Tool on the DBML to blank or setting the Build Action on the generated C# to None.

L2ST4.tt contains a lightweight wrapper around the DBML which is processed using LINQ to XML making the template easier to work with and providing a central for naming rules etc.

This code should be treated as a sample and hasn’t received much testing yet so feel free to leave comments or feedback here.

Some places you could take this template:

  • Generate an interface for your data context to improve mocking
  • Alternative naming and defaults
  • Splitting output into multiple files
  • New languages
[)amien
10 Comments
25
Jun

Experimental LINQ to SQL template

By Damien Guard Categories: .NET and Microsoft Tags: , , , .

A newer version of this LINQ to SQL template is available.

Whilst SqlMetal does a good job of turning your SQL schema into a set of classes for you it doesn't let you customize the code generation process.

Usefully there is now a templating system built into Visual Studio 2008 called Text Templates (T4 for short).

Here is a short (369 line) experimental proof-of-concept T4 template I wrote last night that will generate a data context and associated entity classes as a starting point similar to that produced by SqlMetal.

Download LINQ to SQL template for T4 v0.1 (ZIP) (3 KB)

Once downloaded unzip and drop the DataContext.cs.tt into your project and edit line 17 to set the connection string. You can also edit lines 18 and 19 to set the namespace and class name. The lightweight wrappers around database, table and column can be found at the end of the file - they simply wrap the SQL Server Information_Schema views as briefly as possible.

Within seconds Visual Studio should have created a code-behind file for the DataContext named DataContext.cs.cs with your generated code ready to use :) If you don't like the way the template generates your context you can change it :)

There are limitations with this experimental proof-of-concept including:

  • Processes all and only tables in the database (no views or SP's)
  • Foreign-key relationships are not implemented
  • Column attributes for IsDbGenerated, UpdateCheck and AutoSync not implemented
  • C# only (sorry Julie)
  • Plural and singular naming rules are incomplete
  • Can't modify schema as you could with a designer stage
To learn more about T4:

[)amien

3 Comments

Feed

Feed count