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Info on how to create templates that work in dotnet new and Visual Studio/Visual Studio for Mac

This repo contains a couple samples showing how you can create a .net core template that can be used either by the dotnet command line (dotnet new) or Visual Studio & Visual Studio for Mac. For more info see .NET CLI Templates in Visual Studio .

The samples are in the src/content folder.

Add an issue here, or reach out to @SayedIHashimi on twitter with any questions.

To discover templates that have already been created go to https://dotnetnew.azurewebsites.net/.

The main content here assumes that you are working with Visual Studio 2022 and .net 6. Visual Studio 2022/.net 6 has some updates to the community template experience that Visual Studio 2019 doesn't have. At the bottom there is a section that describes the additional work that is needed to fully support VS2019.

I have some templates that can be used to simplifying creating templates at https://github.com/sayedihashimi/sayedha.templates. These are a good reference for creating your own templates as well.

Finding and installing templates

In .net 6 there has been improvements to dotnet new --search to find templates that are published on nuget.org.

You can use the integrated help to learn more about how to use the search command. You can get the command specific help by executing dotnet new --search -h.

To search for a template by name the syntax you'll use is dotnet new <TEMPLATE_NAME> --search. For example, if you are looking for the .NET Boxed templates, you can execute dotnet new boxed --search. When I executed this command the results I received are below.

> dotnet new boxed --search
Searching for the templates...
Matches from template source: NuGet.org
These templates matched your input: 'boxed'

Template Name                                  Short Name  Author        Language  Package                       Downloads
---------------------------------------------  ----------  ------------  --------  ----------------------------  ---------
ASP.NET Core API Boxed                         api         .NET Boxed    [C#]      Boxed.Templates                     39k
ASP.NET Core GraphQL Boxed                     graphql     .NET Boxed    [C#]      Boxed.Templates                     39k
ASP.NET Core Orleans Boxed                     orleans     .NET Boxed    [C#]      Boxed.Templates                     39k
Boxed templates: Sophon.Boxed.BasicConsoleApp  bca         ZhaoBingwang  [C#]      Sophon.Boxed.BasicConsoleApp         2k
Boxed templates: Sophon.Boxed.BasicWebApi      bwa         ZhaoBingwang  [C#]      Sophon.Boxed.BasicWebApi             1k
NuGet Package Boxed                            nuget       .NET Boxed    [C#]      Boxed.Templates                     39k

To use the template, run the following command to install the package:
   dotnet new --install <PACKAGE_ID>
Example:
   dotnet new --install Boxed.Templates

Since we are interested in the .NET Boxed templates, the install command would be dotnet new --install Boxed.Templates. After installing these templates you can use those templates from the CLI using dotnet new or Visual Studio.

How to uninstall templates

The command to use to uninstall templates is dotnet new --uninstall. If you simply execute dotnet new --uninstall it will display a list of template packs that have been installed, as well as a command for every template pack that you can use to uninstall that template pack. On my machine I have the .NET Boxed template pack installed. When I execute dotnet new --uninstall the result is shown below.

> dotnet new --uninstall
Currently installed items:
   Boxed.Templates
      Version: 6.10.0
      Details:
         Author: Muhammad Rehan Saeed (RehanSaeed.com)
         NuGetSource: https://api.nuget.org/v3/index.json
      Templates:
         ASP.NET Core API Boxed (api) C#
         .editorconfig file (editorconfig) C#
         .gitattributes file (gitattributes) C#
         ASP.NET Core GraphQL Boxed (graphql) C#
         NuGet Package Boxed (nuget) C#
         ASP.NET Core Orleans Boxed (orleans) C#
      Uninstall Command:
         dotnet new --uninstall Boxed.Templates

The command to uninstall this template pack is shown on the last line dotnet new --uninstall Boxed.Templates. After uninstalling the template, you will no longer be able to access that via dotnet new or Visual Studio. If you are using Visual Studio 2019, it's recommended that you restart Visual Studio after uninstalling templates.

Getting started creating templates

To get started creating templates, take a look at the following resources.

Template analyzer

Sayed is working in his free time to create a tool that can be used to analyze .NET Core templates. You can install the analyzer with the command.

> dotnet tool install --global sayedha.template.command

For usage info run templates -h.

After installing the tool you can invoke it by running templates in the command line. You can analyze templates that are stored in a local folder with the -f parameter. You can also analyze templates that are contained in a NuGet package (.nupkg) file with the -p switch.

For example to analyze a folder you would run.

> templates analyze -f <path-to-folder>

When you pass in a path, the tool will search the sub-folders to discover templates. If you are building several templates, you can pass in a parent folder that contains all the templates, and each template that is discovered will be analyzed.

What the tool looks for

Error if missing a required property

Warnings for missing recommended properties

Error if $.tags.type is not set to either project or item Warning if $.symbols.Framework.type is not set to parameter. Warning if $.symbols.Framework.datatype is not set to choice.

Some important things needed to create good templates

Use the schema for completions and validation

You should add the $schema property to your template.json file. Both Visual Studio and Visual Studio Code will provide completions and validation based on the schema. Other editors have similar support as well.

{
"$schema": "http://json.schemastore.org/template",
}

sourceName

In the template.json file you should have a sourceName property declared. The sourceName property is special, and should always be declared. When a project is created, either through the command line or Visual Studio, the project will be given a name. For example, when creating a project with dotnet new you can pass in the -n|--name parameter. In Visual Studio during New Project the user will be prompted to provide a project name. The value provided by the user for project name will replace the string declared in sourceName. This is typically used to replace the namespace declaration in generated files.

{
  "sourceName": "MyCommand",
}

For a full example of sourceName see src/Content/MyCommand/.template.config/template.json

defaultName

When a project is created in Visual Studio, the screen that the user provides the project name will always be pre-populated. If defaultName is declared in the template.json, that value will be used as the default name for the project. Otherwise Project1 is always used. When users create projects from the command line with dotnet new if the -n|--name parameter is not passed in, the defaultName value will be used.

{
  "defaultName": "MyCommandTool",
}

For a full example of sourceName see src/Content/MyCommand/.template.config/template.json

classifications

In Visual Studio when creating a new project there is an All Project Types dropdown that can be used to filter the list of templates shown. You should declare the relevant values from that dropdown in the classifications property of the template.json. Here are some of the values that you can use.

Here is an example of the declaration.

{
  "classifications": ["Console"],
}

Note: in the current preview the Visual Studio New Project Dialog will add all classifications from installed templates into the All Project Types dropdown. That behavior is likely to change, custom classifications will not be listed. You should select the values that you see in Visual Studio (without any additional templates installed) so that the user can filter.

Language and type

In the template.json you should define the language and type for the template in the tags property. For example

"tags": {
  "language": "C#",
  "type":"project"
},

If the type property is not declared, the template will not be shown in the Visual Studio New Project Dialog

Framework

In the template.json file you should indicate what target framework, or frameworks, the template supports. To do that you'll update the symbols section to include a Framework property. Below is an example of what should be included for a template that targets .NET Core 3.1.

"symbols": {
  "Framework": {
    "type": "parameter",
    "description": "The target framework for the project.",
    "datatype": "choice",
    "choices": [
    {
        "choice": "netcoreapp3.1",
        "description": "Target netcoreapp3.1"
    }
    ],
    "replaces": "netcoreapp3.1",
    "defaultValue": "netcoreapp3.1"
  }
}

If your template supports multiple frameworks, add additional values to the choices array.

Note: due to a bug, if your template contains parameters that you want to appear in Visual Studio, you'll need to specify the framework symbol.

Generating ports for web projects

If your template consists of a web project, it's likely that you'll want to generate new port numbers to be used when the template is used. This is a bit complex to do correctly, but we will explain the different parts. When defining the support, for each different port number we want the following to create a command line parameter that can be used to explicitly set the port number. If the port number is not passed in by the user, then we want to generate a port number automatically.

To achieve this, we will need to create three new symbols in the template.json file. We will create the following symbols.

Here is a sample, where we specify the range that we want the port number to be in.

"HttpsPort": {
  "type": "parameter",
  "datatype": "integer",
  "description": "Port number to use for the HTTPS endpoint in launchSettings.json."
},
"HttpsPortGenerated": {
  "type": "generated",
  "generator": "port",
  "parameters": {
  "low": 44300,
  "high": 44399
  }
},
"HttpsPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
  "sourceVariableName": "HttpsPort",
  "fallbackVariableName": "HttpsPortGenerated"
  },
  "replaces": "44345"
}

HttpsPort is the user facing parameter that can be passed in when calling dotnet new.

HttpsPortGenerated is the generated port number. In this example we specified a low and a high value. The generated port number will be between those. These parameters are optional.

HttpsPortReplacer is the symbol that will decide between HttpsPort and HttpsPortGenerated. If a value is provided via the command line (HttpsPort) it will be given preference. Take note of 44345 in this symbol. This is the port number that the source files use. Where ever this string is found in the template content, it will be replaced with the new port number.

For a full example of sourceName see src/Content/MyWebApp/.template.config/template.json

How to test template changes locally

In Visual Studio 2022 you can install templates either via a NuGet package (.nupkg file) or via the folder based path (dotnet new --install [local-file-path]).

In order for a template to appear in Visual Studio 2019 it needs to be installed using a NuGet package (.nupkg file). When developing templates locally, when you are ready to test your template using Visual Studio, follow the steps below.

It's recommended that you delete the cache folders that are used for the templates. The cache folders are in the user home directory (~) under the .templateengine folder. The default path on windows is C:\Users\{username}\.templateengine and for macOS /Users/{username}/.templateengine.

  1. Close all instances of Visual Studio
  2. Create a NuGet package that has the template
  3. Delete Template Engine cache folders (folders under ~/.templateengine)
  4. Install the template using dotnet new --install <path-to-nuget-package>
  5. Start Visual Studio

Here is a PowerShell function that you can add to your profile to make this simpler

function Reset-Templates{
    [cmdletbinding()]
    param(
        [string]$templateEngineUserDir = (join-path -Path $env:USERPROFILE -ChildPath .templateengine)
    )
    process{
        'resetting dotnet new templates. folder: "{0}"' -f $templateEngineUserDir | Write-host
        get-childitem -path $templateEngineUserDir -directory | Select-Object -ExpandProperty FullName | remove-item -recurse -force
        &dotnet new --debug:reinit
    }
}

Some issues that can occur when developing folder based templates

Template updates are not detected

If you are installing/uninstalling folder based templates, you may run into an issue where all template changes are not picked up. For example, you change the description, or add a parameter, in some cases those changes may not be detected by the Template Engine. To force an update run the command below.

dotnet new --debug:rebuildcache

Unable to uninstall a template

If you are having issues uninstalling a template that was installed from a folder, try to change directories (cd) to a different folder and try again.

Common issues

If your template is not appearing in Visual Studio, check the following.

Required properties

Ensure that the following required properties are set in the template.json file.

For tags ensure you have specified the language and type values. See the example below.

  "tags": {
    "language": "C#",
    "type": "project"
  },

The type value can be either project or item, other values should not be used.

primaryOutputs

If you have a single project template, you typically don't have to specify the primaryOutputs property. If your templates.json file has specified primaryOutputs, Visual Studio will open load the project(s) specified. If the value for primaryOutputs is not correct, the project(s) will not load in Visual Studio.

If the value for the primaryOutputs is not correct, the project(s) will not be loaded in Visual Studio

Verify that the NuGet package has the correct files

After creating the .nupkg file you can examine it by extracting the contents using your favorite zip tool. The .nupkg file is just a .zip file with a different file extension. Double check that the .template.config folder is in the package as well as the template.json file and any host files.

How to prevent showing a template in Visual Studio

If you have a template, and do not want that template to appear in Visual Studio when it's been installed using dotnet new --install add the unsupportedHosts property. For example, see the ide.host.json file below.

{
  "$schema": "http://json.schemastore.org/vs-2017.3.host",
  "icon": "icon.png",
  "symbolInfo": [
    {
      "id": "AuthorName",
      "name": {
        "text": "Author Name"
      },
      "isVisible": "true"
    },
    {
      "id": "Description",
      "name": {
        "text": "Description"
      },
      "isVisible": "true"
    }
  ],
  "unsupportedHosts": [
    { 
      "id": "vs"
    } 
  ]
}

The host identifier of "vs" refers to Visual Studio 2019. To exclude from any other host, use the host identifier associated with that product.

How to create a multi-project (Solution) template

Creating a multi-project (solution) template, is very similar to creating a single project template. You'll need to make the following changes to properly create a solution template.

  1. Make sure that the .template.config folder is in the correct folder. It likely should be in the root of the solution. The .sln file should be either in the same directory as .template.config or under it. Same goes for all the content (i.e. projects) that the template should contain.
  2. In the template.json file change the type tag to be solution instead of project.
  3. Update the file name of the solution to be different from sourceName or defaultName, See below for more info.
  4. Update template.json to create unique GUIDs to replace the Project ID in the .sln file.
  5. In template.json make sure to set add a tag, editorTreatAs set to solution.

Solution name best practices

When creating a solution template, make sure that the file name of the solution doesn't match sourceName or defaultName in template.json. For example, if sourceName is set to ContosoBilling, ensure that the solution file is NOT named ContosoBilling.sln. You can change it to ContosoBilling.app.sln and then apply a rename if you want the generated solution file name to match sourceName.

If the solution's file name is allowed to match the sourceName/defaultName, Visual Studio users may see an unexpected "File Modification Detected" dialog immediately after the solution is created and will be prompted to reload.

To rename the solution file, make the following changes to template.json:

  1. In template.json add the editorTreatAs tag and set it to 'solution'.
"tags": {
  "language": "C#",
  "type": "solution",
  "editorTreatAs":"solution"
},

  1. In the symbols section, add the following binding so that the HostIdentifier symbol is defined in your template:

    "HostIdentifier": {
  "type": "bind",
  "binding": "HostIdentifier"
}

  2. In the sources section, add the following modifier to rename the file when projects are created using dotnet new (in Visual Studio, the name specified in the New Project Dialog will be used):

    "condition": "(HostIdentifier == \"dotnetcli\" ||  HostIdentifier == \"dotnetcli-preview\")",
"rename": {
  "ContosoBilling.app.sln": "ContosoBilling.sln"
}

Updating guids

For the last step, we will need to update the template.json file. You can use the guids property to help. Below is a sample

The Project ID values can be found in the .sln file. For example here is a snippet from the SolutionTemplate sample in this repo.

...
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Libraries", "Libraries", "{3C7060D1-D7AF-4B5D-BF1F-BC0E4F39E7ED}"
EndProject
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Apps", "Apps", "{526E49A6-E41B-4136-8662-FC7BF000776A}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SayedHa.Web.MyWeb", "SayedHa.Web.MyWeb\SayedHa.Web.MyWeb.csproj", "{0E62310C-D76A-4681-9926-B1BFFDC379FC}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SayedHa.Web.MyClassLibrary", "SayedHa.Web.MyClassLibrary\SayedHa.Web.MyClassLibrary.csproj", "{032123E7-E4E0-4B17-9564-ECA4B57F30B7}"
EndProject
Global
...

The Project ID is the last Guid listed in the Project node. Below is a sample showing how to get those guids to be updated. Full sample is at template.json

...
  "preferNameDirectory": true,
  "guids": [
    "0E62310C-D76A-4681-9926-B1BFFDC379FC",
    "032123E7-E4E0-4B17-9564-ECA4B57F30B7"
  ],
  "symbols": {
...

Note in the initial preview of Visual Studio where this support appeared, we had a bug that required the .sln file to be listed in primaryOutputs.

Project folder nesting

The structure of the generated .nupkg file depends on the location of the .csproj used to generate it. If the .csproj for the template package is in a directory above the template's \src directory, your template .nupkg will have a nested structure and will fail to generate any output when invoked.

As an example, you might need to have your template .csproj outside of the \src folder because you are using a Directory.Build.props in your \src folder that is incompatible with generating the template package.

The fix to this issue is to add the PackagePath="content" attribute on the <Content> element in your template's .csproj. This will place the contents of the \src directory into the package's \content directory, which is the correct location for template packages.

Before

<!-- Template.csproj -->

<ItemGroup>
    <!-- src\ is the location of the template's source files -->
    <!-- this will generate a .nupkg structure of \content\Content\(src files) -->
    <Content Include="src\**\*.*" />
</ItemGroup>

After

<!-- Template.csproj -->

<ItemGroup>
     <!-- this will generate a .nupkg structure of \content\(src files) -->
    <Content Include="src\**\*.*" PackagePath="content" />
</ItemGroup>

How to ship a template inside of a Visual Studio Extension (vsix)

If you are developing a Visual Studio extension (.vsix file extension), you can deliver your templates inside of the vsix instead of relying on the end-user installing templates via dotnet new --install. This section will walk you through how to create a vsix that contains templates.

In order to create Visual Studio extensions you'll need to install the [Visual Studio SDK](Install the Visual Studio SDK). Let's create a new Visual Studio extension, and add a template into it.

Create the Visual Studio Extension project

First we will need to create a new Visual Studio Extension project. If you have an existing project that you are using, you can open your existing project instead of creating a new project. To create the new project, use the New Project dialog in Visual Studio. When you get to open the New Project dialog, you can search for "vsix" in the search box on the top right. See the image below.

New Project Dialog - Search for vsix

From the list below you can select VSIX Project, with either language that you prefer. The language of the extension doesn't have to be the same language as the template itself. Now that the project is created, we need to make a few modifications to support the project templates.

Before starting to add your template into the Visual Studio extension, you should ensure that your template works without issues from the command line. You'll also want to ensure you've added the additional info to templates that is needed to support Visual Studio. That information was presented previously in this doc.

To add support for templates in a VSIX project, the following additions need to be made.

  1. Add the .nupkg file with your template(s) into the project
  2. Update the VSIX project file to include a new target
  3. Add a pkgdef file to indicate where to look for templates
  4. Update the .vsixmanifest file to have a new asset tag for the template

Adding the .nupkg to your extension

Now you need to add the NuGet package (.nupkg file) to the extension. You'll need to copy the .nupkg file into a folder near the source for the extension. In the in the vsix-with-template folder the file is placed in the assets folder. Now we need to modify the vsix project to pickup, and include, the .nupkg file so that it is included in the final vsix file that is built. Add the following target in the vsix project file (.csproj or .vbproj) file.

<Target Name="PreCreateVsixContainer" BeforeTargets="GetVsixSourceItems">
  <ItemGroup>
    <!-- ensure that the path below is correct -->
    <_TemplatePackage Include="..\assets\*.nupkg" />
  </ItemGroup>
  <Error Text="No template files found." Condition="@(_TemplatePackage-&gt;Count()) == 0" />
  <Message Text="Template nuget packages found: @(_TemplatePackage)" Importance="low" />
  <!-- don't modify the following, the pkgdef file uses the path below -->
  <ItemGroup>
    <VSIXSourceItem Include="@(_TemplatePackage)">
      <VSIXSubPath>ProjectTemplates\</VSIXSubPath>
    </VSIXSourceItem>
  </ItemGroup>
</Target>

The PreCreateVsixContainer target will be called during the build process. It will look for .nupkg files in the assets folder and then include them in the vsix that is produced from the build. You may need to customize the path to where the target looks for these .nupkg files. You can verify that the package was included successfully by opening, or extracting, the .vsix file with your favorite zip utility. The package should be in the ProjectTemplates in the vsix. Now that you've added the NuGet package, and updated the build process to include it, we can move on to the next step.

Adding a pkgdef file

Now that the package is in the vsix, we need to add a pkgdef file so that the extension will register the templates during installation. Add a new file named Templates.pkgdef to your vsix project. If you are using Visual Studio, you can use the text file item template in the New Item dialog. It's important that the name of this .pkgdef file is different from the name of the vsix project. If your vsix project is named Templates, then you'll need to change the name of the new .pkgdef file you just added. The content of this new .pkgdef should be similar to the following.

[$RootKey$\TemplateEngine\Templates\sayedha.template.netcoretool.nuspec\1.0.0]
"InstalledPath"="$PackageFolder$\ProjectTemplates"

Here the only values that you want to modify are sayedha.template.netcoretool.nuspec\1.0.0. You should use a path that is likely to be unique to your organization and project. It doesn't have to match the project or templates that you are including. You can customize the version number in the path as needed as well. The second line in the pkgdef file, indicates where the .nupkg files are located relative to the vsix install folder. You shouldn't modify the second line.

You should also mark the Templates.pkgdef file as Content and IncludeInVsix in the properties grid. See the image below.

tempaltes.pkgdef properties grid

Update the .vsixmanifest

Now we are on the last step. The .vsixmanifest file needs to be updated to pickup the new pkgdef file you just created. Open the source.extension.vsixmanifest file and add the asset tag below into the Assets element.

<Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="File" Path="Templates.pkgdef" />

Adding the asset tag causes Visual Studio to process the new pkgdef file when the extension is installed.

That's it. Now you can build the VSIX project, install the extension and you should see your new template. The next step is to distribute your new extension. You can do that by sharing the .vsix file directly, or publishing to the Visual Studio Marketplace

Supporting Visual Studio 2019

We made some additional changes in Visual Studio 2022/.net 6, which Visual Studio 2019/.net 5 doesn't have. If you have a template(s) that need to support Visual Studio 2019/.net 5, you may need to make some additional changes to get the templates to work in Visual Studio 2019. Below is a summary of the additional work that is needed.

Limitations of Visual Studio 2019 and/or .net 5 regarding community templates.

Parameters

By default all parameters declared in template.json will appear in Visual Studio 2022 if you do not have a ide.host.json (or any Visual Studio host file) file. To control the behavior you can define the tag below in template.json to explicitly state if all parameters should appear or not.

  "tags": {
    "vs_showParametersByDefault": "false"
  },

Values for this tag can be either 'true' or 'false'.

The default value for vs_showParametersByDefault is true if there is no host file detected, and false if a host file is detected.

If you want all parameters to be shown except a set of specific templates, you can use the vs_parametersToHide in tags to hide those specific parameters. The value for this tag should be a semi-colon delimited list of parameter names. For example.

"tags": {
    "vs_parametersToHide": "authorName;useHttps"
  },

Below is some more info based on if a host file is present or not.

No host file present All templates will be shown by default if vs_showParametersByDefault isn't defined in tags. If vs_showParametersByDefault is defined in tags, that value will be used to determine if parameters are shown by default or not. If all templates are shown but there are parameter names listed in vs_parametersToHide, those will not be shown.

Host file present All templates will not be shown by default. To get all of them to appear, set 'vs_showParametersByDefault` to true.

If vs_showParametersByDefault is set to true, and some parameter names are listed in vs_parametersToHide, those will be not be shown in Visual Studio.

Any parameters listed in the host file with isVisible=true will be shown.

TODO: more content will be added soon

How to enable cli templates in Visual Studio and Visual Studio for Mac

The feature to show templates that are installed using the command-line interface (cli) is a preview feature. This feature is disabled by default.

To enable this feature in Visual Studio:

First open the Options dialog, go to Tools > Options. In the dialog go to Environment > Preview Features and then on the right-hand side and select the preview feature named Show all .NET Core templates in the New project dialog. For more info see .NET CLI Templates in Visual Studio .

Visual Studio - Tool > Options > Environment > Preview features

To enable this feature inn Visual Studio for Mac:

Visual Studio - Tool > Options > Environment > Preview features

First open the Preferences dialog, go to Visual Studio (menu) > Preferences.... In the list on the left hand side, select Other > Preview Features and select the preview feature named Show all .NET Core templates in the New project dialog.

Visual Studio support

Starting in previews of 16.8 of Visual Studio we have a feature that can be enabled to show the templates which have been installed with dotnet new. For more info on that take a look at the blog post .NET CLI Templates in Visual Studio .

There are some things that you'll want to make sure you have defined to ensure a good experience for Visual Studio users.

Add an ide.host.json file

Note: in Visual Studio 2022+ the ide.host.json file is no longer required for the template to appear in Visual Studio. If there is an icon named icon.png in the .template.config folder, it will be used for the project template icon in Visual Studio. By default all template parameters will appear in the New Project Dialog in Visual Studio.

In order to get the best support in Visual Studio, you'll want to add an ide.host.json file. This file should be in the .template.config folder next to the template.json file. You'll need to create this file in order to show an icon for the template, to display parameters, to customize the text, and other features.

The schema that you should use when creating this file is shown below.

{
  "$schema": "http://json.schemastore.org/vs-2017.3.host"
}

How to add an icon to be shown in Visual Studio

Note: In Visual Studio 2022, you don't need to create an ide.host.json file to include an icon for the project template. If there is an icon file named icon.png in the .template.config file, it will be picked up automatically. If you'd like to customize that, then create an ide.host.json file as described below.

To add an icon, you will need to declare that in the ide.host.json file. The icon file should be a .png file. The icon file should be in, or under, the .template.config folder. In the ide.host.json file declare the icon property as shown.

{
  "icon": "icon.png"
}

If the icon file is in a sub-folder, provide a relative path in the icon declaration.

In the image below the icon for the sample console template is shown.

New Project Dialog - Custom template with icon

How to make a parameter visible in Visual Studio

Note: in Visual Studio 2022+, by default all template parameters will appear in the New Project Dialog. You do not need to create and ide.host.json file if you want all the parameters to be shown. You can create an ide.host.json if you need to hide some parameters.

In template.json you can declare any number of parameters. Those parameters will not by default show up in Visual Studio. You need to specify which ones should show up in Visual Studio with an ide.host.json file. The MyCommand sample template in this repo has three parameters defined.

The Framework parameter defines the set of choices of target framework that the template supports. This parameter should always be defined for .NET Core templates. This parameter is special, and doesn't need to be declared in the ide.host.json file to be shown in Visual Studio. If this parameter is defined, the Target Framework dropdown in the New Project Dialog will automatically be shown.

In order to show the other two parameters, you will need to add a file named ide.host.json to the .template.config folder. Below is a sample file that shows how to make those appear in Visual Studio.

{
  "$schema": "http://json.schemastore.org/vs-2017.3.host",
  "icon": "icon.png",
  "symbolInfo": [
    {
      "id": "AuthorName",
      "name": {
        "text": "Author Name"
      },
      "isVisible": "true"
    },
    {
      "id": "Description",
      "name": {
        "text": "Description"
      },
      "isVisible": "true"
    }
  ]
}

After adding this declaration, when the template is used in Visual Studio the parameters will be presented to the user as

New Project Dialog - Additional Info Page