Passing parameters to Templates when programmatically generating code

Question

Hi,

I am generating code within a GAT project using T4 and a DSL. Since I need a fine level of control, I have implemented an Action that takes care of the code generation programmatically.

I am wondering how I can pass a parameter to a T4 template in this case?

Here is a snippet of my Action so you can get an idea of how I'm achieving this so far.

Thanks,

Scott.

 

public override void Execute()

{

MyModeller.ModelRoot root;

string template;

string templateOutput;

string dslLocation;

//

// Get a reference to the T4 Templating engine

//

ITextTemplating templateGen = (ITextTemplating) Package.GetGlobalService(typeof(STextTemplating));

dslLocation = <dsl_location>;

if (templateGen != null)

{

//

// Generate Code. Execute the template for each Class in the model

//

using (Store store = new Store())

{

store.LoadDomainModels(typeof(CoreDesignSurfaceDomainModel), typeof(MyModeller.MyModellerDomainModel));

using (Transaction t = store.TransactionManager.BeginTransaction("LoadModel"))

{

// Load the Model

root = MyModeller.MyModellerSerializationHelper.Instance.LoadModel(store, dslLocation, null, null);

foreach (MyModeller.ModelClass type in root.Types)

{

template = GetFromResources(<my_embedded_template2>);

//

// *** HOW DO I PASS 'type' as a parameter to this template??

//

templateOutput = templateGen.ProcessTemplate("c:\\temp\\dummy.txt", template, null, null);

//

// Add the output to the solution

//

AddTemplateToSpecificFileInSolution(templateOutput);

}

}

}

}

}

Answer 1

Hi Scott,

You may do a string replace on "template" variable. Define a placeholder variable in you template and replace it before calling ProcessTemplate.

I use the code below in a Custom Tool, not exactly the same with your code but the same approach.

internal class ActiveWriterTemplatedCodeGenerator : TemplatedCodeGenerator
    {
        protected override byte[] GenerateCode(string inputFileName, string inputFileContent)
        {
            ResourceManager manager =
                new ResourceManager("Altinoren.ActiveWriter.VSPackage",
                                    typeof (ActiveWriterTemplatedCodeGenerator).Assembly);
            FileInfo fi = new FileInfo(inputFileName);
            inputFileContent =
                manager.GetObject("ActiveWriterReport").ToString().Replace("%MODELFILE%", fi.Name).Replace(
                    "%NAMESPACE%", FileNameSpace).Replace("%EXT%", "cs"); // TODO: Get file extension from the project model

            byte[] data = base.GenerateCode(inputFileName, inputFileContent);
            return data;
        }
    }

and the template

<#@ template inherits="Microsoft.VisualStudio.TextTemplating.VSHost.ModelingTextTransformation" debug="true"#>
<#@ output extension=".%EXT%" #>
<#@ ActiveWriter processor="ActiveWriterDirectiveProcessor" requires="fileName='%MODELFILE%'" #>
<#@ import namespace="Altinoren.ActiveWriter.CodeGeneration" #>
<#
    CodeGenerationHelper helper = new CodeGenerationHelper(this.Model, "%NAMESPACE%");
    this.Write(helper.Generate());
#>:

Answer 2

I was thinking of the situation where you have parameters defined in a template like:

<#@ property processor="PropertyProcessor" name="MyParameter" type="MyType" #>

... and you want to programmatically supply the parameters from an Action.

Thanks,

Scott

 

 

 

Answer 3

I might be getting you wrong but, you already got the model loaded by the DirectiveProcessor in your template, right? (Assuming that GAT also provides the processor for your model. I know little about GAT) In the template, you can replace some %ID% placeholder with the ID of the "type", enumerate the loaded model, find your ModelClass with the %ID% supplied and process as you like.

If you absolutely need your property ready to use at the begining, you can write a custom directive processor to load your model and supply a specific object, inherited from RequiresProvidesDirectiveProcessor, but you will still need to supply a hint to find your desired class instance from the model.

You may want to look at http://msdn2.microsoft.com/en-us/library/aa397875.aspx for usage. There's also a sample @
C:\Program Files\Visual Studio 2005 SDK\2006.09\VisualStudioIntegration\Samples\DSLTools\Example.TextTemplating\Example.TextTemplating.DirectiveProcessors
if you have the SDK installed.

Gokhan