Question

is there a way I can read in a namespace and loop through all the classes in a t4 template using reflection or something?

<#foreach (class poco in LoadNamespace("Web.Code.Entities.Poco").Classes ) { #>
public interface I<# poco.ClassName #>Repository 
{
    IQueryable< <# poco.ClassName #> > Get();
    <# poco.ClassName #> Save(<# poco.ClassName #> entity);
    bool Delete(<# poco.ClassName #> entity);
}
<#} #>

example meta data:

namespace Web.Code.Entities.Poco
{
    public class Product
    { 
          public int Id { get; set; }
          public string Name{ get; set; }
          public string Category{ get; set; }
    }

    public class Employee
    { 
          public int Id { get; set; }
          public string Name{ get; set; } 
    }
}

desired output:

    public interface IProductRepository 
    {
        IQueryable<Product> Get();
        Product Save(Product entity);
        bool Delete(Product entity);
    }   

    public interface IEmployeeRepository 
    {
        IQueryable<Employee> Get();
        Employee Save(Employee entity);
        bool Delete(Employee entity);
    }

Answer 1

First install T4Toolbox from here

Then In your Template ensure you have the following lines at top :

<#@ assembly name="EnvDTE" #> 
<#@ import namespace="EnvDTE" #>
<#@ include file="T4Toolbox.tt" #>

Then add these lines of codes:

<#+  

private List<CodeClass> FindClasses(string nameSpace, string className)
{
    List<CodeClass> result=new List<CodeClass>();
    FindClasses(TransformationContext.Project.CodeModel.CodeElements,className,nameSpace,result,false);
    return result;

}


private void FindClasses(CodeElements elements, string className,string searchNamespace,List<CodeClass> result,bool isNamespaceOk)
{
    if (elements==null)return;
    foreach (CodeElement element in elements)
    {       
        if(element is CodeNamespace)
        {
            CodeNamespace ns = element as CodeNamespace;
            if(ns != null)
            {
                if (ns.FullName == searchNamespace)
                    FindClasses(ns.Members, className,searchNamespace,result,true);
                else
                    FindClasses(ns.Members, className,searchNamespace,result,false);
            }
        }
        else if(element is CodeClass && isNamespaceOk)
        {
            CodeClass c = element as CodeClass;
            if (c != null)
            {
                if(c.FullName.Contains(className))
                    result.Add(c);

                FindClasses(c.Members, className,searchNamespace,result,true);
            }

        }
    }
}
#>

Then you can find all classes in a namespace by calling like this (the second parameter filters all classes which their names contain the passed string) :

FindClasses("NameSpace.SubNameSpace",""))//All classes in the specifed namespace 

OR

FindClasses("NameSpace.SubNameSpace","Repository")) //All classes in the specifed namespace which have "Repository" in their names

—————————————— UPDATE FOR VS 2012 ————————–

Use these functions and namespaces if your T4Toolbox is updated for VS 2012 :

//visual studio 2012+
<#@ assembly name="Microsoft.VisualStudio.Shell.11.0" #>
<#@ assembly name="Microsoft.VisualStudio.Shell.Interop" #>
<#@ import namespace="Microsoft.VisualStudio.Shell" #>
<#@ import namespace="Microsoft.VisualStudio.Shell.Interop" #>

private List<CodeClass> FindClasses(string nameSpace, string className,string baseClassName)
{
    List<CodeClass> result=new List<CodeClass>();
    FindClasses(GetProject().CodeModel.CodeElements,className,baseClassName,nameSpace,result,false);
    return result;

}


private void FindClasses(CodeElements elements, string className,string baseClassName,string searchNamespace,List<CodeClass> result,bool isNamespaceOk)
{
    if (elements==null)return;
    foreach (CodeElement element in elements)
    {       
        if(element is CodeNamespace)
        {
            CodeNamespace ns = element as CodeNamespace;
            if(ns != null)
            {
                if (ns.FullName == searchNamespace)
                    FindClasses(ns.Members, className,baseClassName,searchNamespace,result,true);
                else
                    FindClasses(ns.Members, className,baseClassName,searchNamespace,result,false);
            }
        }
        else if(element is CodeClass && isNamespaceOk)
        {
            CodeClass c = element as CodeClass;
            if (c != null)
            {
                if(c.FullName.Contains(className) && (baseClassName==null || (HasIt(c.Bases ,baseClassName) && c.Name != baseClassName)))
                    result.Add(c);

                FindClasses(c.Members, className,baseClassName,searchNamespace,result,true);
            }

        }
    }
}

private bool HasIt(CodeElements elements,string name)
{
    foreach (CodeElement element in elements)
    {
        if (element.Name==name)
            return true;
    }
    return false;
}

private Project GetProject()
{
    // Get DTE
    var dte = (DTE)TransformationContext.Current.GetService(typeof(DTE));

    // Get ProjectItem representing the template file
    ProjectItem projectItem = dte.Solution.FindProjectItem(TransformationContext.Current.Host.TemplateFile);

    // Get the Project of the template file
    Project project = projectItem.ContainingProject;

    return project;
}

private string GetDefaultNamespace()
{

    // Get DTE
    var dte = (DTE)TransformationContext.Current.GetService(typeof(DTE));

    // Get ProjectItem representing the template file
    ProjectItem projectItem = dte.Solution.FindProjectItem(TransformationContext.Current.Host.TemplateFile);

    // Get the Project of the template file
    Project project = projectItem.ContainingProject;

    var vsSolution = (IVsSolution)TransformationContext.Current.GetService(typeof(SVsSolution));
    IVsHierarchy vsHierarchy;
    ErrorHandler.ThrowOnFailure(vsSolution.GetProjectOfUniqueName(project.FullName, out vsHierarchy));
    uint projectItemId;
    ErrorHandler.ThrowOnFailure(vsHierarchy.ParseCanonicalName(projectItem.FileNames[1], out projectItemId));
    object defaultNamespace;
    ErrorHandler.ThrowOnFailure(vsHierarchy.GetProperty(projectItemId, (int)VsHierarchyPropID.DefaultNamespace, out defaultNamespace));
    return ((string)defaultNamespace);
}

so your search will be something like this :

FindClasses(GetDefaultNamespace(),"Repository","RepositoryBase")