Pass ASP.NET Core Appsettings Values to Angular

As part of getting my set of Identity Server 4 sample applications to run in Azure, I needed a way in the Client Application to pass some configuration values from  appsettings.json to the Angular front end that could be used both during server-side rendering and client-side rendering. This application is using JavaScriptServices. This solution may need tweaking if your application isn’t using JavaScriptServices. The code for the client application can be found here.


In this example, we need to pass the address of our Identity Server and API from  appsettings.json to Angular. The following is the settings file for this example.

Providing Configuration Data to Angular

In this application, Angular is loaded from the index action of the home controller. This view can be found in the  Views/Home folder in the  Index.cshtml file. The following is the file before any changes.

The first change needed is to inject the configuration data using ASP.NET Core’s DI system. Add the following two lines at the top of the file.

Now the configuration data from the application is available to this view. Next, we need to pull a couple of values out of the configuration data and pass it to the Angular application. To do this we are going to use the  asp-prerender-data tag helper. You can read more about it in the official docs. The idea is you construct an object which is then serialized and stored in In our example, we are passing the URLs for the Identity and API Applications.

The above is creating a new object with an  apiUrl property and an  identityUrl property. The following is the full completed view for reference.

Angular Server-Side Boot

When Angular gets prerendered on the server-side it runs the code in the  boot.server.ts file. This is where we will set up the providers needed on for the server side prerender. This is the bit that I missed for the longest time when trying to get this example going. I kept trying to find a way to add the providers in the  app.module.server.ts file. Add any providers you need to the  providers constant. For example, the following is passing URLs for an API and Identity Server in addition to the defaults provided by JavaScriptServices.

Lower in the same file we can pass through the configuration values to the client side render as globals on the window object. To do this add a  globals property to the object being passed to the  resolve call.

The above will have the URLs as part of a single object, but you could have each URL as its own property if you prefer.

Angular Client-Side

Now that the server-side has providers for API URL and Identity URL we need to provide the client-side with the same capabilities. These changes will be in the  app.module.browser.ts file. The first step is to add providers for each.

Next, we need functions to return the URLs from the  url_Config property of the window object which the following two functions do.

Wrapping Up

With the above, you can now use your configuration values from ASP.NET Core and pass them through to your Angular application. In hindsight, the process is pretty simple, but getting to that point took me much longer to figure out than I would like to admit. I hope this post saves you some time!

JavaScriptServices: What happen to Aurelia, Vue, and Knockout Templates

With the release of Visual Studio 2017 version 15.3 there are now built in web application templates for Angular, React, and React and Redux.

This is an awesome addition and makes creating new applications with the most popular frameworks simple. What do you do if your framework isn’t one of the top 3 options? JavaScriptServices can help out here and has provided templates for Aurelia, Vue, and Knockout in the past.

Where have they gone?

This is where it gets a little tricky as the templates still exist and are still being maintained, but finding them is a little harder at the moment for some reason. Yeoman was how JavaScriptServices was used in the past, but that has now transitioned to using the .NET CLI and can be added using the following.

After that is complete you will see a list of templates that are now available.

Now you can create an Aurelia project using the following command.

Wrapping up

I was very happy to see that support for the other frameworks hadn’t been dropped. There are a ton of other templates available for dotnet new which can be found here.


Identity Server: Sample Exploration and Initial Project Setup

This post will be a continuation of my exploration around Identity Server which was started with this post which was more of an overview of the space and my motivations for learning about Identity Server. There were a lot of things that were unclear to me as I first started looking through the samples so this post is going to communicate so of those issues and hopefully clear them up for you as well.

After this post, the follow-up post should be more focused on one thing instead of trying to cover so much information in on go.

The following are all the posts in this series.

Identity Server: Introduction
Identity Server: Sample Exploration and Initial Project Setup (this post)
Identity Server: Interactive Login using MVC
Identity Server: From Implicit to Hybrid Flow
Identity Server: Using ASP.NET Core Identity
Identity Server: Using Entity Framework Core for Configuration Data
Identity Server: Usage from Angular

Typical Sample Solution Structure

I started my exploration with the IdentityServer4.Sample repo specifically in the Quickstarts folder. For me, this was a mistake as I didn’t have a good enough grasp on the larger concepts for the code to provide proper guidance. Big surprise here, but using the docs and actually walking through the project creation was very helpful.

The code associated with this blog can be found here. The solution contains three projects.

  • ApiApp – Backend for the application and is a resource that is will require authorization to access. The API will be an ASP.NET Core Web API.
  • ClientApp – Frontend application that will be requesting authorization. This is an ASP.NET Core application that is hosting an Angular (4) app.
  • IdentityApp – This is ASP.NET Core application that is the IdentityServer and will end up authorizing users and issuing tokens for resources.

Identity Application

For the Identity application, create an ASP.NET Core Web Application using the empty template targeting at least ASP.NET Core 1.1. Next, using NuGet install the IdentityServer4 NuGet package.

Now that the IdentityServer4 NuGet package is installed open up the Startup class and add the following to the ConfigureServices function.

The above registers IdentityServer with ASP.NET Core as a service available via dependency injection using temporary and in-memory components as a stand in for testing. The Config class used here will be added a bit later.

Next, the Configure function should look like the following.

The above is a basic Configure function.  app.UseIdentityServer() is the only the only bit related to IdntityServer and it is adding it to the application’s pipeline.

The final part of this application is the Config class which is used to define the in memory test resources for this application. As you can see below it is defining both API resources and Clients. In the future theses, items would be pulled from a datastore.

API Application

For the API application, create an ASP.NET Core Web Application using the Web API template targeting at least ASP.NET Core 1.1. Next, using NuGet install the IdentityServer4.AccessTokenValidation NuGet package.

Ater the above NuGet package installed open up the Startup class. In the Configure function, the IdentityServer middleware needs to be added to the application pipeline before MVC using the app.UseIdentityServerAuthentication function. The following is the full Configure function.

Notice that the address of the of the authority must be specified (this will need to be the address the Identity Application is running on) as well as the ApiName matches the API Resource we added in the Config class of the Identity Application.

Next, in following the IdentityServer quickstart docs add a new IdentityController to the project. Just to be 100% clear this is just a test endpoint to show how to require authorization on a controller and isn’t something that is required to use IdentityServer. The controller has a single Get that returns the type and value of all the user’s claims.

The [Authorize] attribute on the class is the bit that requires calls to this endpoint to have authorization. Keep in mind that the same attribute can be left off the class level and added to specific functions if the whole controller doesn’t require authorization.

Adding the [Authorize] attribute means that the IdentityServer middleware we added in the Startup class will validate the token associated with the request to make sure it is from a trusted issues and that it is valid for this API.

Client Application

For the Client application, I deviated from the samples a bit. Instead of just creating a new MVC application I used JavaScriptServices to generate an Angular (4) application. If you want detail on how that is done you can check out this post (yes it says Angular 2, but the newest version of JavaScriptServices now outputs Angular 4 and the steps haven’t changed). An Angular application is my end goal and why I made this deviation from the samples.

After the Client application has been created use NuGet to add the IdentityModel package. This package is to make interacting with the Identity Application simpler.

For this first go instead of actually interacting with the Identity Application from Angular I will be using it from MVC instead. The detail of interaction from Angular will come in a later post. The IdentityController is what does the interaction with both the Identity Application and the API Application interactions in this version of the client application. The following is the full IdentityController class.

In the above, you can see the IdentityModel in action. Using the DiscoveryClient means the client application only needs to know about the root address of the Identity Application. TokenClient is being used to request a token from the Identity Application for the clientApp using the client secret which in this case is actually the word secret. Keep in mind in a real application secrets should be kept using the ASP.NET Core Secrets manager, see this related post. Also, take note that clientApp and secret are the values that were defined in the Config class of the Identity application.

The rest of the code is taking the token response and making a call to the API application with the response from both of those calls being stored in ViewData for display on the view associated with the controller.

The view is just an Index.cshtml file in the path Views/Identity. The following is the full view.

It isn’t pretty, but the whole point of this controller and view is just for verification that the three applications are properly communicating with each other.

URL Configuration

In this setup, it is important that the URL for the Identity Application and API Application be fixed so they can be accessed by the client. In a more production level application, these values would at a minimum need to be in configuration. The following is the setup used for this solution.

  • Identity Application – http://localhost:5000
  • API Application – http://localhost:5001
  • Client Application – http://localhost:5002

There are a couple of ways to configure test values. The first is to open the project properties and select the Debug tab and set the App URL.

The second option is to go to the Program class for each project and add a UseUrls to the WebHostBuilder like the following.

Wrapping up

After going through the above process I now have a much better understanding of how the very basic setup using Identity Server should work. I hope if you made this far you found some helpful bits.

There is a bit of strangeness using Visual Studio to try and launch all three applications and can result in an error message if multiple of the projects are run in debug mode. For the most part, this can be worked around by only debugging one application at a time. It is a bit annoying at the beginning stages, but once an applications gets past that point I imagian that the Identity Application won’t require much debugging.

If there are any questions please leave a comment and I would be happy to try and help. The finished code can be found here. This basic example will be expanded over time and all the related entries can be found in the IdentityServer category.

Setting Up Visual Studio Code for Debugging ASP.NET Core

Visual Studio Code is a cross-platform source code editor from Microsoft. Out of the box, Code’s language support includes JavaScript, TypeScript, and Node. Using Codes extension system support is available for almost any language you want to use including C#, F#, Elixir, SQL, Swift, and Java. As of this writing, there are 734 language extensions available.

I have been using VS Code since it was first released after Build in 2015, but I have only been using it as an editor never taking advantage of the Debugging capabilities it has available. In this post, I am going to walk through everything that is needed to get a new ASP.NET Core with an Angular front end to run via VS Code’s debugger.

Test application

The first thing I did was to create a new application using JavaScriptServices specifically for this post. For instructions on how to use JavaScriptServices to generate an application check out this post.

On Windows, after the application has been generated and you are in the application directory you can use the following command to open the directory in VS Code.

I am sure there is something similar on Linux and Mac, but I don’t have the environments to try on.

VS Code Overview

When VS Code opens you will see a view close to the following.

The icons down the left side of the screen are for Explorer (shows currently open directory and files), Seach, Source Control (git support is built in), Debug, and Extensions.


The Debug tab will be our focus so click on it which will take you to the following view.

Using the gear with red circle select .NET Core as the environment for the project.

If you don’t see .NET Core listed click More… and click install for the C# option.

After selecting an environment VS Code will add a  launch.json file to the project. This file defines what happens when the start button is clicked in the debugger. At this point clicking the start button to run the application using the debugger will result in an error that  Could not find the preLaunchTask 'build'.

Next, click the Configure Task Runner option and select .NET Core.

This will add a task.json file with a build command that the launch.json is looking for. At this point, I had to restart VS Code to get it to properly pick up the new files. This seems to be an issue that will be fixed with the next release of VS Code and can be tracked using this issue.

After restart and trying to run the debugger again I ran into the error  Run 'Debug: Download .NET Core Debugger' in the Command Palette or open a .NET project directory to download the .NET Core Debugger.

I ended up having to uninstall and reinstall the C# extension and then opening a C# file to get the debugger to download. If you are having this problem make sure and open a C# file before going as far as reinstalling the C# extension.

Hitting run in the debugger now give the error  launch: launch.json must be configured. Change 'program' to the path to the executable file that you would like to debug.

To fix this issue click  Open launch.json and you will find two places with the following.

Change both places to point to the dll your application builds. In the case of my project named  DebugTest the final version ended up being the following.

Wrapping up

Debugging now works! Based on this post it would seem like debugging in VS Code is a big pain, but really after you get it set up once it just works. For new projects, you just have to let it add the

For new projects, you just have to let it add the launch.json and tasks.json and then set the path to your project’s assembly in launch.json. After that, you are ready to go.

I wait too long to figure this process out. I hope this helps you get started with debugging in VS Code.

Upgrading a JavaScript Services Application

As part of the ASP.NET Core Basics series of posts, JavaScript Services was used to create a couple of front end for a basic contacts API using Aurelia and Angular 2. Theses applications were created a few months ago and JavaScript Services has kept moving since then. This post is going to look at one strategy for taking an application created on an older version of JavaScript Services and update it to match the current version. This post will be following the upgrade of the Angular project from ASP.NET Core Basics repo with the starting point of the code being from this release.

The strategy

One of the considerations when doing this upgrade was getting the changes that happen on the ASP.NET Core side of the application and not just the JavaScript bits. In order to make sure that nothing was missed I decided to use JavaScript Services to generate a new application and use that to compare with the implementations in the existing application.

Create comparison application

This is going to assume JavaScript Services is already installed. If it isn’t this page has instructions or this post has sections that deal with creating a new application using JavaScript Services.

The update

Following is the files that changed during this update. This is also the list of files I would check anytime an upgrade needs to be done.

There were a fair amount of changes in the files listed above and instead of posting the code the differences can be found here. The previous diff didn’t contain the webpack.config files and those diffs can be found here and here.

After all the files have been updated make sure to run the following command from a command prompt in your project directory to make sure webpack has vendor related items regenerated.

Wrapping up

This post is a lighter on the details that I do most of the time, but this type of upgrade would just have been a wall of code and not been overly useful and the commits on GitHub are a much better guide to what the upgrade looked like. My feeling is that over time the number of changes going forward may end up being smaller and easier to integrate.

Both the Aurelia and Angular projects have been upgraded and the final version of the code can be found here.

Aurelia with JavaScriptServices: Call to Node module failed

This is going to be a quick post on how to solve an error I go on a new Aurelia project created using JavaScriptServices. For a walk though of creating a project using JavaScripServices check out this post.

The problem

The project got created and would build with no issues, but when I tried to run it I got the following error.

Call to Node module failed with error: Error: Cannot find module ‘./wwwroot/dist/vendor-manifest.json’

The fix

After a little bit of searching I came across this issue on the JavaScriptServices repo with the same error. One of the comments on the issue suggested running the following command from a command prompt in the same directory as your project.

After running that command everything worked like a charm! It is worth noting that the command above can be found in project.json in the scripts prepublish section. From the little bit of reading I did it looks like this command should be rerun anytime a new vendor dependency is added.


I can’t get over how awesome JavaScriptServies is. Steve Sanderson (and team) have done an amazing job. Even with this little hiccup I got this new project up and running 10 times faster than I would have otherwise. It is also going to give me a push to look into webpack.

Angular 2 with ASP.NET Core using JavaScriptServices

This was going to be the fist in a series of posts covering getting started using the RTM versions of ASP.NET Core and Angular 2 together which was going to follow a similar path as the series on Aurelia and ASP.NET Core the first entry of which can be found here.

In the process of writing this post I was reminded of JavaScripServices (they recently added Aurelia support!) and will be using it to get this project up and running instead of doing the work manually.

The code found here can be used as a starting point. The repo contains a solutions with an ASP.NET Core API (Contacts) project and a MCV 6 (Aurelia) project. This post will be add a new MVC 6 project for Angular 2.

JavaScriptServices introduction

JavaScriptServices is an open source project by Microsoft for ASP.NET Core developers to quickly get up and running with one of many JavaScript front ends. The following is their own description.

JavaScriptServices is a set of technologies for ASP.NET Core developers. It provides infrastructure that you’ll find useful if you use Angular 2 / React / Knockout / etc. on the client, or if you build your client-side resources using Webpack, or otherwise want to execute JavaScript on the server at runtime.

The great thing about using the generator that JavaScriptServcies provides is they handle the integration between all the different tools which can be challenging to get right on your own without a lot of time and research.

Project creation

First step is to install the Yeomen generator via npm using the following command from a command prompt.

When installation is complete create a new directory call Angular for the project. In the context of the repo linked above this new directory would be in Contact/src at the same level as the Aurelia and Contacts folders.

Open a command prompt and navigate to the newly created directory and run the following command to kick off the generation process.

This will present you will a list of frameworks to choose from. We are going with Angular 2, but Aurelia, Knockout, React and React with Redux are also available.


Hit enter and it will ask for a project name which gets defaulted to the directory name so just hit enter again unless you want to use a different name. This kicks off the project creation which will take a couple of minutes to complete.

Add new project to existing solution

To include the new Angular project in an existing solution right click on the src folder in the Solution Explorer and select Add > Existing Project.


This shows the open file dialog. Navigate to the directory for the new Angular project and select the Angular project file.


Wrapping up

Set the Angular project as the start up project and hit run and you will find yourself in a fully functional Angular 2 application. It is amazing how simple JavaScriptServices makes getting started with a new project.

The tool setup seems to be one of the biggest pain points with any SPA type JavaScript framework. Aurelia is a little friendlier to ASP.NET Core out of the box than Angular 2, but it still isn’t the simplest process ever. JavaScriptServices is one of those thing I wish I had tried out sooner.

In the near future I am going to redo the Aurelia project in this solution using JavaScriptServices. From there I will come back to the Angular project created in this post and integrate it with the Contact API used in the existing Aurelia application.

Completed code for this post can be found here.