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Creating Custom .NET Project Types with .NET CLI Project Templates


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I recently updated my Visual Studio template for creating Markdown Monster addins in order to support the newer .NET SDK style projects, which are easier to work with and provide a 'ready-to-run' Markdown Monster Addin project which was not quite possible with the older project type and a project template.

Visual Studio templates are nice when you're using Visual Studio as you can easily install an extension from the Visual Studio Gallery. Easy, but... these days not every .NET developer is using Visual Studio anymore, even when building a Windows specific solution like a Markdown Monster Addin.

Creating anything for the Visual Studio Extension system also is a royal pain in the ass: While creating a basic project template is simple enough (you can just export a project to a template), customizing the template to support generic naming and custom output paths and debugging, testing and then wrapping the template into a VSIX in order to publish to the MarketPlace is an exercise in hellish frustration.

dotnet new: Sanity returns

Thankfully, more recently Microsoft has introduced new project formats and alongside with them a newer and decidedly simpler mechanism for distributing project templates via the dotnet new templating experience. The new command line (CLI) tooling that allows performing many tasks like building, restoring, creating, publishing etc. via the dotnet CLI is easy and works for any development environment.

Although this tooling was introduced primarily to support .NET Core, you can also use it on full framework projects, as long as the project uses the new .NET SDK format and so it would also work for my Markdown Monster addin project template which requires full .NET Framework 4.7.2.

Custom Templates

The new project system also supports a straight forward mechanism for creating your own Item or Project templates that work from the command line and therefore can be used with any development environment. It's maybe not quite as smooth as installing an extension from the Visual Studio Marketplace, but command line syntax for installing custom templates and then creating new projects is only a few easily typed commands.

You can also create your own templates and easily publish and share them via NuGet. They are easy to create: You create a template project that contains all the files you want to be contained in your template, and wrap around a project folder hierarchy and add a small metadata file that describes your template.

The wrapped template - or several of them - can then be bundled up into a NuGet package that can be published and shared on the NuGet Repository and can be installed via dotnet new -i <package-name>.

While this is process is not vastly different from the process for Visual Studio Templates, the syntax and metadata used, plus the debug and run cycle is much more manageable. For example, you can simply update your template by reinstalling it and re-running the template. Templates can be installed from online NuGet packages, local NuGet packages, or a local folder. This makes it quick and easy to make changes to a template, test it out again and get it perfect. When done publishing to NuGet for sharing your template with the world is just a few more simple commands away.

Creating a Project Template

Creating a new project template is pretty straight forward but it does involve a few manual steps of creating folders and creating project and template metadata files.

At a high level you need to create:

  • A top level Template Packaging Project
  • A template folder that contains your project files
  • A meta data file that describes the template

The top level project acts as the container for one or more templates and is used to package the templates into a NuGet package. The actual template contains all of your files and the metadata file describes the template, and allows you to customize the files with template expansions when the project is created, so you can customize the project name and class and namespaces of the new project.

The explicit steps are a bit more involved as you end up creating a nested folder hierarchy along with some specifically formatted project and meta data files and I'll take you through these steps next.

Here are the specific steps in summary

  • Create a working project and make sure it works
  • Create a new folder
  • Create the top level template container .csproj file (paste text from below)
  • Inside of the project folder add a templates folder
  • Inside the templates folder create a new folder for your specific template
    (you can create multiple templates into a single template pack)
  • Inside of the custom template folder add a .template.config folder
  • Create a template.json that provides template metadata
  • Optionally use sourceName to replace file and class names and namespaces

The project structure is always the same save for your custom project files. To make this easier to visualize here's what a typical project layout looks like in this case for my MarkdownMonsterAddinProject template:


Figure 1 - A ready to build template project

The root folder holds only the package project and associated icon. The nested templates folder holds one or more child project templates that can be packaged into the single NuGet package.

The actual template folder then contains a .template.config folder with a template.json file that contains the specific template's meta data.

Creating the Folder Structure

The best way to start is to create the folder structure. To demonstrate, I'm going to go through this with my MarkdownMonster addin so the naming reflects that.

At the top level create a folder that matches your template name - think of that as your 'solution' folder: A container for your template project. I used MarkdownMonsterAddinTemplate for the name. This folder only contains the .csproj file and an optional icon for the NuGet package.

The top level Container Project File

Next we'll need to set up the container project file. This file is mostly generic and can just be copied as it with a few replacements. Its sole purpose is to act as a container of meta data for the NuGet package. This project doesn't have specific information about any of the contained templates.

The content project is a standard SDK project with a <PackageType>Template</PackageType> and looks like this:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <PackageType>Template</PackageType>
    <PackageVersion>1.0</PackageVersion>
    <PackageId>MarkdownMonster.AddinProject.Template</PackageId>
    <Title>Markdown Monster Addin Project Template</Title>
    <Authors>Rick Strahl</Authors>
    <Description>Project Template that creates a Markdown Monster Addin that can be customized.</Description>
    <TargetFramework>netstandard2.0</TargetFramework>

    <IncludeContentInPack>true</IncludeContentInPack>
    <IncludeBuildOutput>false</IncludeBuildOutput>
    <ContentTargetFolders>content</ContentTargetFolders>
  </PropertyGroup>
  <PropertyGroup>
    <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
    <PackageOutputPath>./nupkg</PackageOutputPath>    

    <PackageTags>markdown-monster;markdown;wpf;documentation</PackageTags>
    <PackageCopyright>Rick Strahl, West Wind Technologies 2020</PackageCopyright>
    <PackageIcon>icon.png</PackageIcon>
    <PackageProjectUrl>https://github.com/RickStrahl/MarkdownMonsterAddinProjectTemplate</PackageProjectUrl>
  </PropertyGroup>

  <ItemGroup>
    <Content Include="templates\**\*" Exclude="templates\**\bin\**;templates\**\obj\**" />
    <Compile Remove="**\*" />
  </ItemGroup>

  <ItemGroup>
    <None Include="icon.png" Pack="true" PackagePath="" />
  </ItemGroup>

</Project>

This is all boilerplate except for the names and icon. This project is a content project (<includeBuildOutput>false</includeBuildOutput>) that's simply a container for the NuGet package.

The key items that are specific to getting the package built:

  • <PackageType>Template</PackageType>
    marks this as a template project
  • <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
    makes sure that dotnet build creates a package
  • <PackageOutputPath>.\nupkg</PackageOutput>
    a specific path where the .nupkg is generated

Setting up the Template Project Folders

Next you need to create the actual Project Template folder that contains one or more projects.

To do this create this folder structure:

MarkdownMonsterAddinTemplate
-- templates
   -- MarkdownMonsterAddinProject
      -- templates
         -- template.json
      -- $safeprojectname$.csproj          
      -- Addin.cs
      -- ... more files

where MarkdownMonsterAddinProject contains your specific project files. The project folder should contain all the files you want to ship with your template. If you look in Figure 1 you can see I have the required .csproj file, a couple of C# files (Addin.cs and AddinConfiguration.cs) plus a whole bunch of extra related resource files: A couple of images (an icon, screen shot and logo), a custom addin version file and a license file. Anything goes here: I even include binary 7Zip files in there, so that the addin can be packaged into a .zip file for publishing in the MM addin repository. All of these files are specific to my custom project type, so your project template is going to look very different than mine here.

You can add multiple project templates here too: You could add another folder at the same level as the MarkdownMonsterAddinProject and that project type also installs when the template is installed.

Notice that the project file uses $safeprojectname$.csproj for the filename - this is project specific too and that value will be replaced based on a replaceable value that gets created in the template.json file described in the next section.

Create the Meta Data template.json File

Each template includes meta data via a .templates/template.json in the template's project folder. template.json describes the template and optionally provides for some replacement values you can use to replace values in both the content of text files as well as for file names.

Here's what my templates.json looks like:

{
  "$schema": "http://json.schemastore.org/template",
  "author": "Rick Strahl, West Wind Technologies",
  "classifications": ["common", "library", "markdown-monster", "WPF"],
  "identity": "MarkdownMonsterAddin.Project",
  "name": "Markdown Monster Addin Project",
  "shortName": "markdownmonsteraddin", 
  "tags": {
    "language": "C#",
    "type": "project"
  },
  "sourceName": "$safeprojectname$",    // replace w/ project name or -n val
}

Most of these are pretty obvious as they describe the template. The identity is a unique Id that identifies the addin, but the shortname is what displays in the dotnet new list of project types - the latter is the one you want to name carefully since that's what end users see.

Customizing Template Content and File Names with sourceName and symbols

One thing that almost any generic template has to do, is to customize the name of the of the generated output file names and some of the content for things like class name(s) and namespaces.

For example, in Markdown Monster's Addin Template I want the main class name to match the name of the project that user selected. If my project's name is MySweetAddin, I want to change the main class name to public class MySweetAddin as well as the namespace. I also want the main addin file to be renamed to MySweetAddin.cs and the configuration file to MySweetAddinConfigurat.cs.

There are two ways you can customize templates using:

  • The built-in sourceName Property
  • The custom symbols Collection

The sourceName Property

"sourceName": "$safeprojectname$";

The not so obvious sourceName property can be used to replace a token value with the name of the project that is generated when the project is created.

To keep with the MySweetAddin example from before, all instances of text $safeprojectname$ are replaced with MySweetAddin in the content of any of the text files. It also replaces filenames - so $safeprojectname$.csproj gets renamed to MySweetAddin.csproj, which indirectly controls the name of the output assembly as MySweetAddin.dll.

To give you an idea what replacement values in a source file look like here is my Addin.cs class file with replacements for $safeprojectname$:


Figure 2 - you can replace the project name using the sourceName configuration

Note: I'm using $safeprojectname$ as my replacement value merely out of convenience because that's what the old Visual Studio extension used. The string doesn't have to have the $ at the beginning and end - it can be any string that gets replaced. Microsoft's examples often use namespaces, but I find that not a good choice because you're likely to use this value for your main class, file name and probably part of the name for secondary files and namespaces. I do recommend you use some sort of delimiter just to make it obvious that you're looking at a replaceable value in your template.

Note that project name used for sourceName replacement is determined by the project name created with dotnet new or dotnet new -n <projectName>:

# Project name is MySweetAddin based on **source folder**
c:\temp\MySweetAddin> dotnet new

# Project is MySweetAddin via **-n** parameter
c:\temp\projects\test> dotnet new -n MySweetAddin

Custom Symbol Mappings

The sourceName property is most likely all that you need, but if you need to pass additional parameters for expansion or behavior you can do so via the symbols setting. This key is a collection of 'parameters' that can be applied as replacement values similar to the way that sourceName works, except that you get to specify the names.

Here's a custom -c|--company parameter you can pass for example:

"symbols": {
    "company": {
      "type": "parameter",
      "defaultValue": "Your Company",
      "replaces": "$company$"
    }
  }

This replaces any occurrence of $company$ with whatever is passed via the -c command line:

dotnet new markdownmonsteraddin -c "West Wind Technologies"

In the example below the $company$ value in the author key is replaced with West Wind Technologies.

{
  "id": "$safeprojectname$",
  "name": "$safeprojectname$",
  "summary": "Description of $safeprojectname$ in a short paragraph",
  "description": "Describe $safeprojectname$ with a long description",    
  "version": "0.01",
  "minVersion": "1.70",
  
  "author": "© $company$",   // <---- Company replaced with West Wind Technologies
  
  "updated": "2020-10-01T12:00:00Z"
}

Now we have all the bits and pieces in place and we should be able to build our new project.

Building and Publishing the Project

To build a project is very simple now. From the root project's folder (or from within Visual Studio or other IDE) just build your project:

dotnet build

This creates a NuGet Package in the .\nupkg folder (or whatever you specified as your output folder) that you can distribute. But... before you do that you probably want to test the project and see how it works. Once you install, most likely you'll discover a few things that aren't set up quite right and you'll go back and forth a few times fixing small issues with your template to get it just right.

Trying out your Template Locally

The good news is that unlike Visual Studio extensions it's super easy to install, update and uninstall project/item templates using the dotnet new command.

You can also install your project template from:

  • A NuGet package from NuGet.org
    dotnet new -i <package-id>
  • A local NuGet Package from a folder
    dotnet new -i <path-to-nuget-package>
  • A Project Folder
    dotnet new -i <path-to-project-template-folder>

For initial testing the easiest is usually to use your project template folder, which in my example here is the path to the MarkdownMonsterAddinProject folder in Figure 1.

To test the addin:

# Install template from local folder
dotnet new -i "<project-path>\templates\MarkdownMonsterAddinProject"

# create a new project folder
md \projects\MySweetAddin
cd \projects\MySweetAddin

# create a new project
dotnet new -n MySweetAddin -c "West Wind Technologies"

# Open project in IDE (VS Code here, but you can use Visual Studio)
code .

If you install your template and you find out that it's not working quite right, you can simply fix the template in your project and then re-run the dotnet new -i command to re-install the template from the folder. You can then simply delete the contents of the generated project folder and re-run the install:

# assuming you're still in the MySweetAddin folder
remove-item *.* -f -recurse

# reinstall the template
dotnet new -i "<project-path>\templates\MarkdownMonsterAddinProject"

# create the project again
dotnet new -n MySweetAddin -c "West Wind Technologies"
code .

Rinse and repeat until you get it right!

Building the NuGet Package

Once you have the project template working the way you want it you can package it up and create a NuGet package and optionally publish it on NuGet.org.

# From the top level Project Folder
dotnet build -c Release

Here's what the NuGet package looks like in the excellent Package Explorer tool:


Figure 3 - The compiled template as a NuGet package in NuGet Package Explorer

Publishing to NuGet

If you want to share your project template you can build the NuGet package and push it to NuGet. To do this you can use the Package Explorer and simply click on the Publish button after you've set up your NuGet account and have configured your NuGet Publish Id.

Alternately you can use a publish script like this:

if (test-path ./nupkg) {
    remove-item ./nupkg -Force -Recurse
}   

dotnet build -c Release

$filename = gci "./nupkg/*.nupkg" | sort LastWriteTime | select -last 1 | select -ExpandProperty "Name"
$len = $filename.length

if ($len -gt 0) {
    Write-Host "Signing... $filename"
    nuget sign  ".\nupkg\$filename"   -CertificateSubject "West Wind Technologies" -timestamper " http://timestamp.comodoca.com"
       
    # nuget setapikey <key> -source nuget.org
       
    nuget push  ".\nupkg\$filename" -source nuget.org
}

Here's the package, published on NuGet:


Figure 4 - The published package on NuGet

Installing and Running from NuGet

Once the package has been published you can now install it from NuGet.org by simply running:

# install/update the project template
dotnet new -i MarkdownMonster.AddinProject.Template

# Create the new project
md \projects\MySweetAddin
cd \projects\MySweetAddin
dotnet new markdownmonsteraddin -n MySweetAddin -c "West Wind Technologies"

# Open in editor
code .

# should just work!
dotnet build -c Release

# Run Markdown Monster with the addin installed
mm

If all went well and I did my job testing, the project should just compile and in this case just run. And sure enough, here's what it looks like installing and running the addin:


Figure 5 - Putting it all together: Installing, creating, building and running the project template

Cool. One nice thing about the new .NET SDK templates is that they can be customized easily to work generically so I've been able to make this template work so it installs the addin in the default addin location and 'just works out of the box'.

Sweet!

What about Visual Studio?

You can of course also open this generated project in Visual Studio; you don't need to compile or run from the command line as I'm doing here.

To open the project in Visual Studio:

  • Open the project folder
  • Click on the .csproj file
  • Save a solution file

Here's what the generated folder and Visual Studio look like when the project is loaded there:


Figure 6 - Opening the new project in Visual Studio

Visual Studio Extension or Dotnet New Template

In this article I've gone into detail on how to create a project template with the dotnet new SDK tooling and it's pretty easy to create these templates. Compared to creating a Visual Studio addin the process of the project template creation is much simpler and much more maintainable. It's easier to create the templates, much, much easier to test and update them, and the format layouts are straight-forward so that coming back to them after a few months won't be a shock. By comparison Visual Studio Project Template Extensions are a bit painful, especially the VSIX creation process.

The big benefit of a Visual Studio Extension is discoverability and ease of installation in Visual Studio. Using the Visual Studio Marketplace is very easy and quick - although you do have to restart Visual Studio these days to install new extensions.

dotnet new templates unfortunately do not show up in Visual Studio's New Project dialog (yet), so you're pretty much relegated to using the dotnet new command line to create projects. Since that's a one time deal that's probably not a big deal.

On the plus side, unlike Visual Studio project templates, you can use dotnet new templates for any other IDE, so they work with Visual Studio, Rider and any OmniSharp based environment.

For example, JetBrains Rider picks up my new template in the New Solution dialog:


Figure 7 - JetBrains Rider shows dotnet new templates in its New Solution dialog

Dotnet New Templates in Visual Studio Preview

Visual Studio 16.8 Preview now also has Preview feature that allows you to see dotnet new templates via Tools-> Options-> Configuration-> Preview Features:


Figure 7 - You can enable dotnet new Templates in Visual Studio in Preview

And here's what this looks like to select the project:


Figure 8 - Selecting a dotnet new template is still a bit rough in the Preview

As you can see my Markdown Monster Addin template shows up but it's kinda rough and doesn't use the package icon. You also can't provide any custom parameters to the template (ie. the company parameter in the example). But still this gives basically the same functionality as a Visual Studio extension and it gives you the option to still just invoke the template from Visual Studio using the familiar New Project menu option.

I suspect going forward, Microsoft is going to shift most if not all project templates to use dotnet new style templates for projects and items, but for now this is a preview feature. You need to use the current Visual Studio 16.8 Preview and enable the explicit feature flag.

Summary

Creating project templates can be very productive for certain scenarios. In my scenario of allowing users to easily create new Addins for Markdown Monster, I certainly want to make that process as easy as possible. Nothing sucks more than trying to get stuck before you ever get your first bit of code to run. Project templates make it possible to create a new project that's ready to run with just a few dotnet CLI commands which is awesome.

Compared to the Visual Studio project template and VSIX process, the new dotnet new template based approach is much simpler, works with any type of development IDE and is much more flexible in terms of maintaining the template. It's also vastly easier to test, debug and rebuild templates during the template creation process.

For the time being I'll publish both project templates for the Visual Studio VSIX and the dotnet new tooling. I'm curious what people prefer. I suspect anybody using Visual Studio probably would prefer the Extension manager for installation over jumping out to the command line, but even if you do, it's literally 2 short CLI commands to create a new project which is hardly difficult.

I think going forward, the .NET Template system is going to be the way to go, but for the time being I guess I'll have both the Visual Studio Extension and the dotnet new template in place. At least until MS breaks VSIX again. 😄

Resources

this post created and published with the Markdown Monster Editor
Posted in .NET  .NET Core  

The Voices of Reason


 

Kathleen Dollard
October 06, 2020

# re: Creating a dotnet new Project Template

Great article!!!

We also hate that VSIX makes template installation so hard, so we're fixing that!

Visual Studio 2019 16.8, currently in preview, has a feature flag (Tools/Options/Preview Features) named "Show all .NET Core templates in the New Project Dialog". Check that and you should find your template in Visual Studio.

We'd like feedback on this, and we know this may result in a lot of templates! You can filter with the search (at the top) and the three combo boxes. Let us know what you're interested in searching/filtering on.

You can find more about .NET CLI templates appearing in Visual Studio in this blog post.


Rick Strahl
October 06, 2020

# re: Creating Custom .NET Project Types with dotnet new Project Templates

@Kathleen - thanks for the ref about Templates in VS. I've updated the post to reflect that support.


Ignat Andrei
October 28, 2020

# re: Creating Custom .NET Project Types with .NET CLI Project Templates

Just asking : could we run custom code in our template after dotnet new is doing his job ?


Rick Strahl
October 28, 2020

# re: Creating Custom .NET Project Types with .NET CLI Project Templates

@Ignat - not that I know of, and frankly I think that would be a terrible idea as that would be an invitation for malicious code to execute.

Since they are delivered as NuGet packages, you're limited to the NuGet operation which AFAIK doesn't include code execution of any kind.

If you need templates that execute code you likely need to build for Visual Studio and use a VSIX.


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