Tag Archives: dotnetcore

Building C# Project-based Azure Functions in Visual Studio Code

I’ve been using the Azure Functions for Visual Studio Code for some time now and they continue to evolve in great ways. The latest shift threw me for a loop so I thought I would document some of it for those who may not have started yet. I should also state that for the past year or so I have focused on writing my functions with JavaScript just because I like to mix things up a bit and it also makes it easier to share Azure Functions with devs who are not .NET focused.

I’ve also written about creating Azure Functions with VS Code in MSDN Magazine but again, this has changed since I wrote about it. I’ve been using the version 2 APIs for a while so I’m not talking (well, writing) about that change from v1 to v2 here but the change in the experience using the Azure Functions extension.

Also notable is that the Azure Functions team actually recommends using Visual Studio for building C# based apps and VS Code for JavaScript. But I’m so often on my MacBook and love using VS Code so I am going down this path with C# anyway.

Having revisited the docs enough times to finally notice some key information, I realize why the experience has changed with the extension working with C#. Previously, I’d worked with C# script functions (.csx) which is the same as what you use when you work directly in the portal. But the extension templates now drive you to C# project functions and there’s a big difference. C# script functions are more like the javascript functions. They depend on a manually created function.json file to define the bindings and can install the appropriate extension packages based on the bindings. The csx files are compiled at run time. With a C# class library, you develop as you would other C# class libraries – installing the relevant packages and then using attributes to identify methods as Azure Functions as well as trigger, input and output bindings. When you compile the library, the Azure Functions tooling will generate a function.json file for you that gets deployed.

Because I was used to creating functions with JavaScript or the C# script path, the new default for the Azure Function extension that uses C# class libraries instead really threw me for a loop. So I decided to document walking through this workflow as I has to learn it. I think I still prefer the lighter weight C# script (.csx) or JavaScript flow but that might align with my preference in many scenarios for VS Code over Visual Studio.

Preparing Visual Studio Code

So first things first: you’ll need to install the Azure Functions and Azure Account extensions into VS Code, Azure Functions extension relies on the Azure Functions Core Tools. The extension installation instructions will help  you get all that you need and the extension does check for updates and prompt you to update those tools as needed. In fact, I got this prompt last night.2019-01-16_09-28-10.png

With the extensions installed, it is time to create a function app project. You should already have a folder created to house your project and you might as well have it open in VS Code. Mine is named AzureFunctionProj.

Then you can click on the “Create New Project” icon on the function bar (the icons show up when you hover over the bar) to create a new Function App project inside your folder.

2019-01-17_18-11-39.png

This part of the workflow has not changed.

  1. It will ask you to point to a folder and the open folder should be there as a default to select.
  2. It will then have you select a language you’ll use in your app. From the options (C#, JavaScript, Python (still a preview) and Java (also a preview), I’ll choose C#.

As a result a new .NET Core project will be created using the template and you’ll see the following in the folder explorer:

2019-01-17_18-19-58.png

All of these files inside AzureFunctionProj folder were created by the template. Most importantly the csproj file where I’ve highlighted some of the most relevant settings.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <AzureFunctionsVersion>v2</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
   <PackageReference Include="Microsoft.NET.Sdk.Functions"
                     Version="1.0.24" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
     <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

Creating a function in the function app is where things are quite a bit different.

You begin as always with the “add a function” icon2019-01-17_18-11-39 copy.png

The first step is familiar, selecting which folder has the function app that the function should be in:

2019-01-17_22-06-37.png

I’ll choose AzureFunctionProj.

Then there are a number of trigger templates to choose from which is nice but more interesting are the three options at the bottom:

2019-01-17_16-42-25.pngFirst is the project runtime and I definitely want v2 (“~2”). You can use different languages for different functions in the function app. This is showing the default I chose already: C#. And finally, the list of trigger templates is filtered to “Verified”.

You can change these options by clicking on them.

The filter options are Verified, Core and All. Core and All currently reveal the same list, which includes a few extra preview triggers: DurableFunctionsOrchestration, SendGrid, EventHubTrigger and IotHubTrigger.

2019-01-17_16-43-20.png

Now in the past I was creating JavaScript functions inside my .NET Core Function App but now I am going to continue with C# because this is where things really surprised me. I’ll choose  HttpTrigger and am then prompted to provide a name. I’ll just leave the default: HttpTriggerCSharp. I’m then asked to provide a namespace name for the class that will be created. Default is “Company.Project”. I’ll change it to FunctionTests.HttpTest1. The final bit of info to be collected is that you need to choose the security for the function. Of the options, I will select Anonymous because its a demo and I don’t want to have to deal with credentials.

That’s it. The function is created.

Some More Class Library Project Differences

My past experience gave me the expectation that a new folder is created inside the app function folder with the name of the function and inside there, would be a class file for the function and a function.json file to contain the binding configurations. the class file was there (though not in its own folder). But there was no function.json file. Also  interesting and new to me were the FunctionName attribute on the Run method and  the HttpTrigger attribute on the HttpRequest in the Run method’s signature. Also, I’m not used to having all of those using statements when using csx script.2019-01-19_15-16-45.png

When building the project, .NET Core reads that attribute and builds a function.json that goes in the bin folder for deployment. 2019-01-17_22-38-03.png

But it’s more than just the familiar bindings. Notice the generatedBy , configurationSource , scriptFile and entryPoint tags.

So the first binding, the httpTrigger binding, looks familiar to me. The function will respond to httpTrigger.

You can test out this default either by running or debugging. To run, you can use VS Code’s CTRL-F5 keyboard combo or, if you prefer using the CLI, you use Azure Function CLI command:

func host start

That will run the function and provide a url to try out. The template “stake-in-the-ground” method is written to accept either a query parameter or JSON in the body. I’ll just use a query parameter:

http://localhost:7071/api/HttpTriggerCSharp?name=Julie

And the browser outputs

2019-01-19_15-57-04.png

Adding an Output Binding to
Azure Cosmos DB

What if I wanted to add an output binding? I’m used to doing that by editing function.json. But since I’m on this path of attribute defined bindings, I will add the binding that way. Let’s add an output binding for Azure Cosmos DB. That way this function will respond to an HTTP Request and insert some data into a Cosmos DB database. I already have an Azure Cosmos DB account, so I will define this to target a new collection in a new database in the existing account.

In order to use work with a Azure Cosmos DB binding, I need to add the relevant package to my project. Because I’m building my function using a C# class library, I can just do this as I would for any other Nuget package…by adding it directly to csproj or adding the package with the dotnet core CLI:

But now I’m just writing a C# class library so I can add the package either with the dotnet CLI or just add it manually into .csproj. I’ll use the CLI:

dotnet add package Microsoft.Azure.WebJobs.Extensions.CosmosDB --version 3.0.3

Note that if I were building the function with JavaScript or  C# script, I would need to register the package using the tools CLI (func extensions install -p packagename).

Now the package is in csproj:

<ItemGroup>
  <PackageReference 
    Include="Microsoft.Azure.WebJobs.Extensions.CosmosDb"
    Version="3.0.3"/>
  <PackageReference
    Include="Microsoft.NET.Sdk.Functions"
    Version="1.0.24"/>
</ItemGroup>
After restoring, I can add the output binding. Currently the default function is asynchronous and you can’t add out parameters to an async method. Return values are one option. See https://docs.microsoft.com/en-us/azure/azure-functions/functions-triggers-bindings#using-the-function-return-value for details. ICollector or IAsyncCollector is another (https://docs.microsoft.com/en-us/azure/azure-functions/functions-dotnet-class-library#writing-multiple-output-values).
But I’m going to  just make the Run method synchronous and create an output parameter instead. Like the trigger binding parameter, I’ll need to add an attribute to the output parameter to specify the binding. I’m also supplying parameters for the database and collection names, the name of the setting that has the connection string to the database account and one last setting to ensure the database and collection get created if needed.
[FunctionName("HttpTriggerCSharp")]
public static ActionResult Run(
   [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post",                 Route = null)]
   HttpRequest req,
   [CosmosDB(databaseName: "CSharpDatabase",
             collectionName: "CSharpCollection",
             ConnectionStringSetting = "MyCosmosDBConnection",
             CreateIfNotExists=true)] out dynamic document,
   ILogger log)
I added the MyCosmosDBConnection is defined in the local.settings.json file:
{
  "IsEncrypted": false,
  "Values": {
     "AzureWebJobsStorage": "",
     "FUNCTIONS_WORKER_RUNTIME": "dotnet",
     "MyCosmosDBConnection": "this is where my connection string goes",
   }
}
Note that if you were creating a new function with an Azure Cosmos DB trigger, the tooling would prompt you for all of the relevant database information, include that an attribute in the function code and add them to the function.json.
Now there is just one last puzzle piece. The function expects me to provide a value to the document variable which the binding will then insert into the database. The full class listing is below and in there the single line for populating the document with a Name and Added property is highlighted in red. The function and the binding will do all of the rest.
using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;

namespace FunctionTests.HttpTest1
{
  public static class HttpTriggerCSharp
  {
    [FunctionName("HttpTriggerCSharp")]
    public static ActionResult Run(
      [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)]
      HttpRequest req, 
      [CosmosDB(databaseName: "CSharpDatabase",
                collectionName: "CSharpCollection",
                ConnectionStringSetting = "MyCosmosDBConnection",
                CreateIfNotExists=true)] out dynamic document,   
      ILogger log)
    {
      log.LogInformation("C# HTTP trigger function processed a request.");
      string name = req.Query["name"];
      document=new { Name = name, Added = DateTime.Now };
      return name != null
        ? (ActionResult)new OkObjectResult($"Hello, {name}")
        : new BadRequestObjectResult("Please pass a name on the query string");
     }
  }
}
Based on my previous experience of manually configuring function.json, I expected after building, the function.json in the bin folder to include the CosmosDB output binding information but it didn’t. Again, this is due to the differences between JavaScript/C# script functions and C# library functions.
Within VS Code I can run or debug the function. Debug is F5 or the debug icon. To run, without debugging, you can use CTRL-F5 or  the tools CLI command:
func host start
When using the CLI command, I found in my testing that the version I’m using seems to require me to run dotnet clean first for it to succeed. CTRL-F5 does that step for you . I made a note of this in a pre-existing GitHub issue. You can read that here.
There is a lot of useful info in the official docs. Two that I leaned on are:

First Foray into .NET Core 2.0

I have to start somewhere so I started wtih super baby steps. Downloading the .NET Core 2 nightly build and trying to create a simple console app. Right away I failed miserably. The reason? The nightly builds have already jumped the shark! They are working on 2.1.0 and I accidentally grabbed that. And that was a little too bleeding edge for me.

There is a docker image that you can use quite easily but I wanted to try CLI, VS Code and Visual Studio. Therefore I wanted to just install the bits right on my machine.

What I’ll show you are  my first tests I did on macOS and on Windows 10. I like to do this just to make sure things are actually running properly. Note that on macOS, I just installed this new version directly on my machine where I have other versions of .NET Core. Key is that there is no production work on there dependent on other versions, so I won’t mess up anything important. The versions can live side by side. It’s just that for someone like me who “knows enough to be dangerous”, it’s easy to get tangled up with the versions even though I know tricks like creating a local nuget.config file and also specifying a version in global.json. On Windows, however, I am using a clean VM that has no other versions of .NET on it. That’s the smart way anyway. Although I did try the not smart way of installig it on my machine that already has all kinds of versions of all kinds of frameworks on it and even with my versioning tricks, I could not get 2.0.0 to do a restore or build.

I mentioned above that I originally downloaded the wrong version of the SDK. (Note that the typical SDK install also includes the runtime….so I got the wrong versoins of both. You can read the gory details of that in this GitHub issue which I kept updating as I sorted the problem out.) I want to stick with .NET Core 2.0.0. The installer for that is tucked away in a branch of github.com/dotnet/cli rather than grabbing the absolute latest from the master. Instead go to https://github.com/dotnet/cli/tree/release/2.0.0. There is a solid 2.0.0 version — 2.0.0-preview2-006391. That’s the one I’m using on Windows and macOS.

2017-06-11_12-23-16.jpg

Make Sure NuGet Knows Where to Find Packages

You can update your global NuGet.Config before creating projects. Alternatively, you can create a project and then add a local NuGet.config file to it.

On Mac, the global config file at [user]/.nuget/NuGet. Here s a screenshot if like me, macOS is not your primary platform and you still struggle with these things.

2017-06-11_12-32-15.jpg

In Windows, it’s at %APPDATA%\NuGet\.

I keep a link to the “Configuring NuGet behavior” doc handy for when I forget where to find that.

I added these two keys to my PackageSources section:

<add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />

<add key="dotnet-core" value="https://dotnet.myget.org/F/dotnet-core/api/v3/index.json"/>

 Now it’s time to create a project

I’m on the Mac, so, to Terminal we will go.

I’ve created a new folder called EFCore20 – I know this is .NET Core, but eventually I plan to add in EF Core 2.0 as well.
My plan is to create a .NET Core console app (this will rely on netcoreapp2.0) and a library. The libray will be based on the netstandard2.0 library . That means its a library I’ll be able to use from a huge variety of apps, including .NET 4.6.1 based apps. EF Core 2.0 will also rely on .NET Standard 2.0, so any app or API that can consume netstandard, can also consume EF Core 2.0. Read more about that in this EF Core 2.0 announcement on GitHub.

I created one folder for each inside the EFCore20 folder:

netcore2console
netstandard2lib

Then I cd’d into the netcore2console app to create that app with the command:

dotnet new console.
That’s all it takes. This creates a tiny little Hello World app. The dotnet new command will also perform a dotnet restore after creating the files. This is the first moment you will see if things are wokring again. If the restore fails, it will tell you immediately.
This is the message I got when had things misaligned:
Error message: error MSB4236: The SDK ‘Microsoft.NET.Sdk’ specified could not be found.
The “specified” SDK is the currently installed version of whatever SDK you are referencing. In my case, the default for dotnet enw console is “dotnetcore” with the version being whatever version is installed.
Most likely the problem is that  you haven’t provided the correct URI for dotnet to find the proper NuGet packages.
If you don’t want to mess with the global config, you can create a local NuGet.config file in the folder with the app. In it’s entirety, it would look like:
<?xml version="1.0" encoding="utf-8"?>
 <configuration>
  <packageSources>
   <addkey="nuget.org"value="https://api.nuget.org/v3/index.json"protocolVersion="3"/>
   <addkey="dotnet-core"value="https://dotnet.myget.org/F/dotnet-core/api/v3/index.json"/>
  </packageSources>
</configuration>
Even though dotnet new will call restore, I like to call
dotnet restore
explicitly. (Control freak)
If it restored correctly, then the next step for validation is
dotnet build
And hopefully that gives you no errors as well. It shouldn’t.
Finally,
dotnet run
should result in spitting out
Hello World!
And now I know it’s working. Silly little bit but I want to verify this before I waste my time writing a bunh of code that isn’t going to run because I don’t even have .NET Core installed properly.
Another point of interest is what files were created by dotnet new console.
It’s easier to see them if I open them up in Visual Studio Code which I can do by typing
code .
There are only 2 files. The csproj with the project metadata and a program file.  The csproj file says that the target framework is netcoreapp2.0.

2017-06-11_14-09-46

The program file just spits out Hello World when it starts up.
2017-06-11_14-10-17
Here is a screenshot of all of the steps at the command line from dotnet new console to the Hello World! output including my extra dotnet restore. Another thing I like about the explicit restore is that it’s showing me more detailed info about the restore.
2017-06-11_14-03-19
Next I want to make sure I can get a .NET Standard library also working.
Still in the terminal (or console or PS if you’re on Windows), I now get into the 2nd sub folder, EF Core2/netstandardlibrary. dotnet new library defaults to using netstandard for the library. So that makes it easy.
dotnet new library
The library is created and the packages it needs are restored.
Here are the default contents of this new library, again, shown in VS Code.
Ntice that its csproj says the target framework is netstandard2.0.2017-06-11_14-16-09
And there’s an empty class file.
2017-06-11_14-18-12
I’ll modify the class to add a public method that returns a string: “Why, Hello There!”.
2017-06-11_14-22-01

Now I’ll go into the csproj for the console app and give it a project reference to the library. The intellisense does not (yet?) help me with this and my memory sucks*, so I head to Nate McMaster’s handy project.json to csproj mind mapper aka Project.json to MSBuild conversion guide to remind myself the syntax of a project reference. I add this below the property group section in the console app’s csproj file

 

<ItemGroup>
  <ProjectReference Include="..\netstandard2lib\netstandard2lib.csproj"/>
</ItemGroup>
Running dotnet restore and dotnet build again will help identify if you’ve got a typo in there. I often do.
Now I’ll modify the Program.cs file to also call output the resultls of caling the HiYa method from my library:
2017-06-11_14-31-39

And then back out to my terminal window (though I can also do it inside VS Code’s built-in terminal). I dotnet build the library and then change to the console folder. Rebuild that and run it and …voila

  netcore2console dotnet run

Hello World!

Why, Hello There!

  netcore2console

So now I know that .NET Core 2 (preview from a nightly build) is running properly on my machine and that I can create and use a .NET Standard 2.0 library. That means I can go ahead and confidently start creating a .NET Standard 2.0 library to host some EF Core 2.0 logic.

I also repeated this entire thing on my Windows machine. Not only does that let me know I can use this version of .NET Core there, but I will also do some work from within Visual Studio with the .NET Core 2.0 preview.

*(duh, I should just make myself a snippet in VS Code!)

Cloning a GitHub Repo in Visual Studio 2017 …and a Quiz

When showing off some VS2017 features at our VTdotNET meetup, I made a last minute decision to demo the ability to clone a repository right from GitHub. Then I thought I would combine that with other things I planned to demo.

I already had just the right repo sitting in my GitHub account. A small ASP.NET Core project that was built with Visual Studio 2015 using project.json for its metadata. It’s at https://github.com/julielerman/NetCoreSolutionToMigrateToVS2017.

I had this same solution on my laptop already to use for another demo: showing off VS2017’s ability to auto-migrate a project.json based solution to the new csproj based format for .NET Core projects.

Clever me, I decided to kill two birds with one stone. Clone the repo and have the migration run as it was opening that solution.

So I started up Visual Studio 2017 (since I wanted to show how fast that is) and began the process of cloning the solution from my GitHub repo. I already had my credentials set up and was able to go to File, Open and Open from Source Control.

2017-03-21_21-52-52

This opens the Team Explorer window and I clicked the Clone option, which then opened a window showing all of the accounts I’m connected to.

2017-03-21_22-06-28

I expanded my own account and scrolled down to the repo I wanted, selected it and clicked the Clone button.

2017-03-21_22-11-20

The solution got cloned and then it opened up in Visual Studio.

2017-03-21_22-13-53

But it never triggered the migration! And if you look at the solution, you can see that the project I expanded still has its xproj file and its project.json file. At the time I was confused but now that I know what happened, the answer to why this didn’t migrate is very visible in that screenshot of the Solution Explorer. However, one of the developers who was watching this and had just done another demo with Visual Studio 2017, identified the problem quickly.

Let’s move on for some more clues.

I closed the solution. Then from File/Open, I browsed to the place where it had been saved on my computer, and selected the sln file to open. This time, the same exact solution opening up in VS2017, did indeed trigger the migration, which is quite obvious thanks to this screen.

2017-03-21_22-18-17

Then I let the migrate feature do its job. When it was finished, you can see that the project no longer has its xproj and project.json files.

2017-03-21_22-21-42

Now, look at this new Solution Explorer screenshot compared to the previous one.

And then take a look at the list of new VS2017 features in the Release Notes (https://www.visualstudio.com/en-us/news/releasenotes/vs2017-relnotes) under the section IDE and see if you can tell what the cloning did differently when opening the solution than just opening the solution directly from the drive.

Also, I will find out if this is by design or possible a behavior that can get modified to behave the way I had expected. 🙂

DotNet Core Version Confusion

I see people scratching their heads over this a lot so am dropping it here even though I’m sure it’s stated in many places already.

When you are at the dotnet command line (aka the CLI aka Command Line Interface) and type ‘dotnet’ you will be shown the version of the runtime.

When you add the version parameter (‘dotnet –version’) that will return the version of the SDK (aka CLI aka Command Line Interface) that you are working with.

Here’s an example:

If you are confused, you’re not alone. There’s a good discussion/debate on GitHub about how to alleviate this confusion at  What should dotnet –version display?