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Giving the .NET smart components a try–The Smart Combobox

Microsoft announced last month, the .NET Smart Components, an experimental set of AI-powered UI components that can be added to your .NET apps. They asked us to give these components a try and share our feedback.

And that is exactly what we are going to do in this blog post.

Right now we have 3 components available:

  • Smart Paste
  • Smart Textarea
  • Smart Combobox

If you want a good overview of the available components, check out the video from Steve Sanderson:

Although the video shows some compelling use cases for each of these components, we have to start somewhere. So in this post I’ll focus on the Smart Combobox as it doesn’t require any language model backend.

Here is the main use case that Smart Combobox tries to solve:

The problem with a traditional combobox is that if there are a lot of options available, it can be a challenge to select the right item from the list. With Smart Combobox,  the component uses semantic matching to find an item from the list that most closely matches the input you provided.

Integrate Smart Combobox in an ASP.NET Core MVC app

We start by creating a new ASP.NET Core MVC application.

Remark: The Smart Components are supported in both Blazor and MVC/RazorPages applications.

Add the SmartComponents.AspNetCore NuGet package to your project:

dotnet add package --prerelease SmartComponents.AspNetCore

The Smart Combobox doesn’t need a language model backend. However it does need some AI magic. In this case it is done through embeddings, a way of converting natural-language strings into numerical vectors. We can use our local machine to calculate these embeddings by including the following NuGet package:

dotnet add package --prerelease SmartComponents.LocalEmbeddings

Open your Program.cs file and add the following lines to register the necessary services:

Now open the _ViewImports.cshtml file (in the Views folder) and reference the Smart Component tag helpers:

Okay. Now we can finally add our Smart combobox to our Razor view. We need to specify a URL that will provide the list of possible values:

Now we need to create an API endpoint that returns these values:

As you can see in the code above, we precalculate the embeddings.

Let’s now run the application and give our Smart Combobox a try. We type ‘XBox’ and get 'Toys & Games' back:

Remark: The first time I tried this it didn’t work and I got no results back. The root cause of the issue turned out to be localisation. The similary-treshold value was specified as a float e.g. 0.6.  On my local machine this was converted to 6 which was out of range(supported values are in the range of 0-1)

To fix it I had to explicitly add the RequestLocalizatonMiddleware:

Don’t forget to fill out this survey once you have given these components a try!

More information

Introducing .NET Smart Components - AI-powered UI controls - .NET Blog (

smartcomponents/docs/ at main · dotnet-smartcomponents/smartcomponents (

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