The GAX Property Directive

One of the things that really bother me about T4 templates is the lack of direct parameter support (at least in the Visual Studio 2008/.NET 3 timeframe).

In an earlier post, I passed parameter by writing the parameter data to a file outside of the template and reading the data from within. I used a common assembly linked to both sides of the divide. This works for me, but it is really hacky.

GAX Template Host

During my preparation for my Portland Code Camp presentation, I came across Guidance Automation Toolkit for Visual Studio 2008. It has its own TemplateHost that includes a Dictionary of parameters.

Parameters are exposed to the Template through a custom directive. On the template, the parameter is declared using a directive like this:

<#@ property processor="PropertyProcessor" name="MyName" type="String" #>

The directive contains the following parts:

processor	Should be "PropertyProcessor" (there may be a way to write your own processor, I haven’t gone down that rat hole yet).
name	The Variable name that can appear in your code. It works just like a variable, however, tangable T4 Editor doesn’t provide Intenesence (I wouldn’t have expected it).
type	Any .NET Type that the template knows about. You should use the .NET type name (as opposed to C# or VB.NET type).

In C# the parameters are created like this:

var arguments = new Dictionary();
arguments.Add("MyProperty", new PropertyData("String", typeof(string)));

To pass parameters from your code you need to create a Dictionary<string, PropertyData>, add your parameters and pass them as the second argument into the TemplateHost constructor (the first can be any string as far as I can tell).

Simple Sample

The Template

<#@ template language="C#" debug="True" #>
<#@ output extension="txt" #>
<#@ assembly name="System.dll" #>
<#@ import namespace="System" #>
<#@ property processor="PropertyProcessor" name="MyProperty" type="Nullable<Int32>"#>
<#@ property processor="PropertyProcessor" name="MyName" type="String"#>
My Property Test
<# if (MyProperty.HasValue) {#>
Property Value: <#= MyProperty.Value #>!
<#}#>
Name: <#= MyName #>

C# code

static void Main(string[] args)
{
    // Prepare template parameters
    var arguments = new Dictionary<string, PropertyData>();
    arguments.Add("MyProperty", new PropertyData(42, typeof(int?)));
    arguments.Add("MyName", new PropertyData("Jack Stephens", typeof(string)));

    // Initialize GAX template host
    // The Template Host is from GAX, not the default host
    var host = new TemplateHost("Random String", arguments);
    host.TemplateFile = Path.Combine(Directory.GetCurrentDirectory(), 
        "PropertyTest.tt");

    // Transform template
    string template = File.ReadAllText(host.TemplateFile);

    ITextTemplatingEngine engine = new Engine();
    string output = engine.ProcessTemplate(template, host);

    Console.Write(output);
    Console.ReadKey();
}

References

• Understanding T4: <#@ property #> directive
• Guidance Automation Extensions Download

Portland Code Camp 2011 Presentation Notes

Again, I'm late getting this up. I will give usual excuses of being busy. In the future I will not promise anything before the next weekend after the code camp.

Since I developed this talk on this blog, this entry will essentially be a link list. I put a copy of the slides in Google doc and you can reference it here

This presentation is similar, but not the same as a presentation I gave at the Boise Code Camp in February. In the interest of being DRY (Don’t Repeat Yourself) I will reference the notes for that presentation.

Tools

For this presentation, I used the Tangible T4 Editory and the T4 Toolbox.

Template Parts

I presented a slide that showed the basic template parts in a small mock template:

<#@ template language="C#" #>
<#@ directive property=“value” #>
<# var item = "Statement Block"; #>
Text Block 
<#= "Expression Block" #>
<#+ 
    string ClassFeatureBlock(string thingy)
    {
        return thingy;
    } 
#>

Hello World Monty

I showed some of the elementary features of T4 templates by refactoring a basic template that would create a text file that contained the infamous words “Hello World”. A script of that exercise is here

Basic Code Generation Demonstration

To demonstrate Code Generation I set out to generate a simple T-SQL Select Statement using Sql Management Objects (SMO).

Here I will refer to the Boise Code Camp Notes.

Generating Multiple Files using T4 Toolbox

I used the result of the Basic Code Generation Demonstration to attempt to generate select scripts for all the tables in a given database. This demonstration was based on a series of blog posts by Oleg Synch (Part 1, Part 2, Part 3 & Part 4).

I do intend to give my take on this process. Perhaps that is why I'm over a week late on these notes. I will add a link to these notes later.

GAX Property Directive

I discussed using Guidance Automation Extensions's property directive to overcome T4's lack of native support for passing parameters into templates. This part was based on another Oleg Synch article Understanding T4: <#@ property #> directive.

Again, I will add links to future blogs post(s) on this subject here.

Generating a Nullable ADO.NET DataSet Wrapper

This is when I went to Show and Tell Mode. I demonstrate a Nullable DataSet Wrapper that I wrote in these blog entries. I wrote the templates in VB.NET to generate code in C#.

Part 1, Part 2, Part 3 & Part 4

Last Word

This presentation reached too far and, like Icarus, I failed to hit the mark. The number of forward links is a sign of that. I intend to back-blog in the areas the missing material and add links when I am done.