Alexa.Tip – Build Better Responses in .NET With SSML

In this Alexa.Tip series, we explore some little bits of code that can make your life easier in developing Alexa Skills in many languages including C# + .NET, node.jS + TypeScript, Kotlin, etc. We look at concepts that developers might not be aware of, design patterns that and how they can be applied to voice application development, best practices, and more!

In this post, we are looking at a VERY simple, but useful tool when developing Alexa Skills – SSML or Speech Synthesis Markup Language.

If you’re new to voice application development, SSML is a common standard among all the big players – Alexa, Google, Cortana, etc. At its simplest form, it’s a simple set of XML elements that are used to tell the Voice Assistant (such as Alexa) how to speak your response in a particular way. The alternative to using SSML is to return simple text as a string and let the assistant respond with their normal speech. However, this commonly falls short on things like:

  • Abbreviations
  • Dates
  • Emphasis
  • Pauses
  • Tone
  • Pitch

This is especially true when the assistant is reading out a particularly long set of text. It becomes too… robotic. Ironically…

So let’s look at an example of a C# and .NET response using simple text:

Function.cs

public SkillResponse SimpleTextResponse()
{
    return ResponseBuilder.Tell(new PlainTextOutputSpeech
    {
        Text = "When one door of happiness closes, another opens; but often we look so long at the closed door that we do not see the one which has been opened for us."
    });
}

With a response like this, Alexa will likely read it too quickly which can really diminish the power behind such a great quote (by Helen Keller).

Now we can very easily update a response like this to give ourselves something more powerful:

Function.cs

public SkillResponse RichTextResponse()
{
    return ResponseBuilder.Tell(new SsmlOutputSpeech
    {
        Ssml = 
            @"<speak>
                When <emphasis level=""moderate"">one</emphasis> door of happiness closes, another opens;
                <break time=""1.5s""/>
                <s>but often we look so long at the <emphasis level=""strong"">closed</emphasis> door that we do not see the one which has been opened for us.</s>
            </speak>"
    });
}

Now with this, we can add emphasis of different levels on certain words, add breaks in the speech when we need to, and separate contextual sentences!

For a full list of SSML tags that Alexa supports check this out:
https://developer.amazon.com/docs/custom-skills/speech-synthesis-markup-language-ssml-reference.html

And be sure to check back for more intro to expert level tips on Alexa Skill development!
Or take a look at other posts in the Alexa.Tip series here!

Side note: I’m also working on a tool to make building SSML responses even better – especially for very large and dynamic pieces of conversations. The idea is to build a more Fluid Design approach for something like this:

// returns a string
return SsmlBuilder.Speak("When")
    .Emphasis("one", Emphasis.Moderate)
    .Speak("door of hapiness closes, another opens;)
    .Break(1.5)
    .Sentence("but often we look so long at the closed door that we do not see the one which has been opened for us.")
    .Build();

Or something like:

// returns a string - uses string searching
return SsmlBuilder.Speak("When one door of happiness closes, another opens; but often we look so long at the closed door that we do not see the one which has been opened for us.")
    .Emphasis("one", Emphasis.Moderate)
    .Break(";")
    .Sentence("but often we look so long at the closed door that we do not see the one which has been opened for us.")
    .Emphasis("closed", Emphasis.Strong)
    .Build();

Or:

// returns a string - uses indexes and lengths
return SsmlBuilder.Speak("When one door of happiness closes, another opens; but often we look so long at the closed door that we do not see the one which has been opened for us.")
    .Emphasis(4, 3, Emphasis.Moderate)
    .Break(47)
    .Sentence(49, 112)
    .Emphasis(59, 6, Emphasis.Strong)
    .Build();

Let me know what you think in the comments or on twitter @Suave_Pirate – Would you rather build SSML Responses like this or is writing the XML in a big fat string working alright for you?


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile and AI developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.


voicify_logo
I’m the Director and Principal Architect over at Voicify. Learn how you can use the Voice Experience Platform to bring your brand into the world of voice on Alexa, Google Assistant, Cortana, chat bots, and more: https://voicify.com/


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Xamarin.Tip – Adding a Password Toggle Button in iOS

In a previous post, we looked at how easy it was to add a Password Toggle button in our Xamarin.Android apps (or native Android since it was only in the xml layout): Xamarin.Tip – Adding a Password Toggle Button in Android

So in this post, let’s work toward a similar behavior in our Xamarin Native iOS!

The basic premise is to extend the UITextField control and add a SubView to it for the button. Then on this UIButton.TouchUpInside, we want to toggle the UITextField.SecureTextEntry boolean property.

With that in mind, there are a number of ways we can do this!

  • Create a custom PasswordToggleTextField and design it in a xib to drag and drop the button
  • Add the UIButton at runtime everywhere we want to use it
  • My Favorite: Use NativeBehaviors and create a reusable behavior that can be attached to any given UITextField.

Let’s continue down this path with the NativeBehaviors approach. Of course, if you don’t want to do it this way, you can simply copy the code within the Behavior we create and apply it anywhere else.

NativeBehaviors is a package I created just a little while back that brings the Xamarin.Forms style Behavior pattern to native iOS, Android, and UWP controls. So if you’ve written Xamarin.Forms Behaviors before, this should be super familiar!

Let’s do this by creating a simple TextFieldTogglePasswordBehavior.

TextFieldTogglePasswordBehavior.cs

/// <summary>
/// Text field toggle password behavior.
/// </summary>
public class TextFieldTogglePasswordBehavior : NativeBehavior<UITextField>
{
    public override string BehaviorName => nameof(TextFieldTogglePasswordBehavior);

    private UIButton _togglePasswordButton;

    /// <summary>
    /// Attach show/hide button
    /// </summary>
    /// <param name="bindable">Bindable.</param>
    protected override void OnAttachedTo(UITextField bindable)
    {
        _togglePasswordButton = new UIButton()
        {
            Frame = new CGRect(0, 0, 50, 8)
        };

        _togglePasswordButton.SetTitle(bindable.SecureTextEntry ? "Show" : "Hide", UIControlState.Normal);
        _togglePasswordButton.SetTitleColor(UIColor.White, UIControlState.Normal);
        _togglePasswordButton.SetAttributedTitle(new Foundation.NSAttributedString(bindable.SecureTextEntry ? "Show" : "Hide", UIFont.SystemFontOfSize(12)), UIControlState.Normal);
        _togglePasswordButton.TouchUpInside += (sender, e) =>
        {
            var updatedIsPassword = !bindable.SecureTextEntry;
            bindable.SecureTextEntry = updatedIsPassword;
            _togglePasswordButton.SetTitle(updatedIsPassword ? "Show" : "Hide", UIControlState.Normal);
            _togglePasswordButton.SetAttributedTitle(new Foundation.NSAttributedString(updatedIsPassword ? "Show" : "Hide", UIFont.SystemFontOfSize(12)), UIControlState.Normal);
        };
        _togglePasswordButton.TitleLabel.TextColor = UIColor.White;
        bindable.RightViewMode = UITextFieldViewMode.Always;
        bindable.RightView = _togglePasswordButton;
        bindable.RightViewRect(new CGRect(0,0, 50,8));
    }

    /// <summary>
    /// Kill the button
    /// </summary>
    /// <param name="bindable">Bindable.</param>
    protected override void OnDetachingFrom(UITextField bindable)
    {
        _togglePasswordButton = null;
        bindable.RightView = null;
    }
}

If you read through the code a bit, you noticed that we simply create a UIButton, set its text to UIColor.White, and then update the text of the button to either “Show” or “Hide” depending on the state, and then in the TouchUpInside handler, we update that state as well as the SecureTextEntry property of the parent UITextField this behavior gets attached to!

You can also update this to use icons instead of regular text buttons to get a behavior closer to the Android treatment if you wanted. It’s just a button, so go crazy.

Now let’s take this behavior and attach it to an existing UITextField control that we have added to a UIViewController in our Storyboard.

In this example, I’m using a custom UITextField called MaterialTextField to show that this behavior is usable on the built in controls as well as any other custom UITextField:

LoginViewController.cs

public class LoginViewController : UIViewController 
{
    // note: this is now reusable if you want to apply the behavior to multiple fields
    // without creating a bunch of new instances.
    private readonly TextFieldTogglePasswordBehavior _togglePasswordBehavior = new TextFieldTogglePasswordBehavior();

    protected void ViewDidLoad() 
    {
        PasswordTextField.AttachBehavior(_togglePasswordBehavior);
    }
}

And that’s it! If we want to remove the button and detach the behavior, all we have to do is call:

PasswordTextField.DetachBehavior(_togglePasswordBehavior);

With all that together, we get a pretty neat control!

Screen Shot 2018-03-15 at 11.04.00 AMScreen Shot 2018-03-15 at 11.03.54 AM

In a future post, we can look at how to achieve this same concept in Xamarin.Forms – without using custom renderers!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Tip – Embed Your Xamarin.Forms Pages in Your iOS ViewControllers

The number one complaint I hear about Xamarin.Forms is the slow startup time of the applications that use it. The team at Xamarin has done a lot to help with this and give some more options such as XAML Compilation, Lazy Loading, and Ahead of Time Compilation. Check out some of David Ortinau’s suggestions here: 5 Ways to Boost Xamarin.Forms App Startup Time.

However, one of the best ways I’ve found to help with this issue is to use Xamarin.Forms Embedding to its full potential. Embedding became available in Xamarin.Forms 2.5 and at a high level allows you to embed your Xamarin.Forms pages into your Native Xamarin views by using the extension methods .CreateFragment(Context context); for Android and .CreateViewController(); for iOS. This is most commonly used for when you want to share some UI in your Xamarin Native apps using Xamarin.Forms, however you still need to call Xamarin.Forms.Init() which is one of the main culprits in the slow startup time.

For Android embedding, see: Xamarin.Tip – Embed Your Xamarin.Forms Pages in Your Android Activities

iOS

The solution proposed here still allows you to create almost all of your views in Xamarin.Forms by using embedding, but requires some architecture and design changes. The premise is this:

  • First ViewController is non-Xamarin.Forms and loads your app right away
  • Init Xamarin.Forms after this ViewController is loaded
  • Embed Xamarin.Forms pages in other ViewControllers
  • Lift navigation out of Xamarin.Forms and into the native navigation.

This also has advantages outside the startup time such as better performance on transitions, more natural look and feel to end-users, performance gains in other areas, and a smaller app-size.

This means:

  • No NavigationPage
  • No Xamarin.Forms toolbar (using the native UINavigationBar control instead)
  • Still have MVVM and all our bindings we would expect

So if you’re already using a framework that is not tied down to Xamarin.Forms such as MvvmLight, you don’t have to change much behind the scenes since the INavigationService is abstracted.

Let’s kick this off by creating an inheritable ViewController that handles the embedding and layout how we want. Be sure to use your Storyboard and have the RootViewController be a UINavigationController, then use this embeddable ViewController within that.

XamarinFormsViewController

/// <summary>
/// Base xamarin forms view controller. Used for embedding a Xamarin.Forms page within a native view controller.
/// When inheriting from this, be sure to create a ViewController within the storyboard as well so that navigation
/// can properly work.
/// </summary>
public abstract class XamarinFormsViewController<TPage> : UIViewController
    where TPage : ContentPage, new()
{
    protected TPage _page;


    public XamarinFormsViewController(IntPtr handle) : base(handle)
    {
    }

    /// <summary>
    /// Load the Xamarin.Forms Page's ViewController into the parent
    /// </summary>
    public override void ViewDidLoad()
    {
        base.ViewDidLoad();
        _page = new TPage();
        var xamarinFormsController = _page.CreateViewController();
        AddChildViewController(xamarinFormsController);
        View.AddSubview(xamarinFormsController.View);
        xamarinFormsController.DidMoveToParentViewController(this);

        // add whatever other settings you want - ex:
        EdgesForExtendedLayout = UIKit.UIRectEdge.None;
        ExtendedLayoutIncludesOpaqueBars = false;
        AutomaticallyAdjustsScrollViewInsets = false;

    }
}

When creating a child of this XamarinFormsViewController, be sure to also create an empty ViewController in your .storyboard file for each unique type. This is required for handling navigation using the storyboard and root UINavigationViewController. If you’re using .xib files for some reason, then don’t worry about it, just instantiate the XamarinFormsViewController itself (you’ll have to add the other constructor overloads though).

So now we can create a simple Xamarin.Forms page:

SomePage.xaml

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"     x:Class="MyApp.Pages.SomePage">
    <ContentPage.Content>
        <Grid>
            <Label Text="I'm Embedded!" HorizontalOptions="Center" VerticalOptions="Center"/>
        </Grid>
    </ContentPage.Content>
</ContentPage>

Then create the associated ViewController:

SomeViewController.cs

public class SomeViewController: XamarinFormsViewController<SomePage>
{
    protected void ViewDidLoad()
    {
        base.ViewDidLoad();

        NavigationItem.Title = "Some title";
    }
}

Now all we have to do is kick off this SomeViewController after calling Xamarin.Forms.Init() and we are good to go! If we have a MainController we can call it before navigating if it isn’t initialized, or execute it in ViewDidLoad or a similar lifecycle event.

MainController.cs

public class MainController: UIViewController
{    

    protected override void ViewDidLoad()
    {
        base.ViewDidLoad();

        // assume SomeButton is created and named in the Storyboard file
        SomeButton.TouchUpInside += delegate 
        {
             if(!Xamarin.Forms.Forms.IsInitialized)
                 Xamarin.Forms.Forms.Init(this, savedInstance);

             var someController = this.Storyboard.InstantiateViewController("SomeController") as SomeViewController;
             NavigationController.PushViewController(someController, true);
        }
    } 
}

And there you have it! Some new Xamarin.Forms embedding for performance and other extra benefits 🙂

In future posts of this subject, we’ll look at extending interactions between the Xamarin.Forms Page and the native Activity and ViewControllers, using advanced native components with the embedded Xamarin.Forms Page, and more!

Let me know what you think of this pattern – have you used it? What else would you want to hear about it??

Be sure to checkout some of the Xamarin examples on embedding too!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Tip – Adding a Password Toggle Button in Android

Here’s another quick tip to use when building your Android apps whether in Xamarin, or native in Java/Kotlin. Depending on the target audience of your application, you may find it necessary to add a password toggle button to your password EditText to allow users to view and hide their password while typing it.

In this post, we will explore how to do this in Android natively while future posts will cover iOS (which is more involved) as well as building a Xamarin.Forms custom Entry view (no renderer’s required!) to handle the toggling.

There are two places to achieve this in Android – in the xml of the layout resource, or in the code behind where manipulating the view. Luckily, Android (unlike iOS) has this feature built in to the properties of the TextInputLayout control.

We get the ability to show the button as well as apply a custom Drawable if we want!

Using the Layout Resource

Here is an example using the TextInputLayout from the xml side to wrap an EditText:

activity_login.axml

<android.support.design.widget.TextInputLayout
    android:id="@+id/password_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:passwordToggleEnabled="true"
    app:passwordToggleTint="@android:color/white">
    <android.support.design.widget.TextInputEditText
        android:id="@+id/password_editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:password="true"
        android:hint="Password"
        android:textColor="@android:color/white"
        android:inputType="textPassword" />
</android.support.design.widget.TextInputLayout>

Notice the two properties:

app:passwordToggleEnabled="true"

and

app:passwordToggleTint="@android:color/white"

These are the two that control showing the password toggle. Alternatively, you can set the

app:passwordToggleDrawable="@drawable/someDrawable"

Using Code

If you’re manipulating your TextInputLayout in your code, you can also update these fields very easily:

LoginActivity.cs

public class LoginActivity : AppCompatActivity
{
    protected override void OnCreate(Bundle savedInstance)
    {
        base.OnCreate(savedInstance);
        SetContentView(Resource.Layout.activity_login);

        var editTextLayout = FindViewById<TextInputLayout>(Resource.Id.password_layout);

        editTextLayout.PasswordVisibilityToggleEnabled = true;
    }
}

That’s it!

Results

Take a look for yourself!

Screen Shot 2018-03-15 at 11.04.31 AM
Screen Shot 2018-03-15 at 11.04.40 AM


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Tip – Embed Your Xamarin.Forms Pages in Your Android Activities

The number one complaint I hear about Xamarin.Forms is the slow startup time of the applications that use it. The team at Xamarin has done a lot to help with this and give some more options such as XAML Compilation, Lazy Loading, and Ahead of Time Compilation. Check out some of David Ortinau’s suggestions here: 5 Ways to Boost Xamarin.Forms App Startup Time.

However, one of the best ways I’ve found to help with this issue is to use Xamarin.Forms Embedding to its full potential. Embedding became available in Xamarin.Forms 2.5 and at a high level allows you to embed your Xamarin.Forms pages into your Native Xamarin views by using the extension methods .CreateFragment(Context context); for Android and .CreateViewController(); for iOS. This is most commonly used for when you want to share some UI in your Xamarin Native apps using Xamarin.Forms, however you still need to call Xamarin.Forms.Init() which is one of the main culprits in the slow startup time.

The solution proposed here still allows you to create almost all of your views in Xamarin.Forms by using embedding, but requires some architecture and design changes. The premise is this:

  • First Activity is non-Xamarin.Forms and loads your app right away
  • Init Xamarin.Forms after this activity is loaded
  • Embed Xamarin.Forms pages in other Activities
  • Lift navigation out of Xamarin.Forms and into the native navigation.

This also has advantages outside the startup time such as better performance on transitions, more natural look and feel to end-users, performance gains in other areas, and a smaller app-size.

This means:

  • No NavigationPage
  • No Xamarin.Forms toolbar (using the native Toolbar control instead)
  • Still have MVVM and all our bindings we would expect

So if you’re already using a framework that is not tied down to Xamarin.Forms such as MvvmLight, you don’t have to change much behind the scenes since the INavigationService is abstracted.

Let’s kick this off by creating an inheritable Activity that handles the embedding and layout how we want.

xamarin_forms_activity.axml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <android.support.design.widget.AppBarLayout     
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="?android:attr/actionBarSize"
        android:layout_gravity="top"
        app:elevation="0dp">
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?android:attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
    </android.support.design.widget.AppBarLayout>
    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

This layout gives us the native Android toolbar (with the shadow! Another plus!) and a space for us to embed in this FrameLayout.

Now let’s create the Activity:

XamarinFormsActivity.cs

/// <summary>
/// Base xamarin forms activity.
/// This activity contains a single fragment in the layout and renders the fragment pulled from the Xamarin.Forms page
/// </summary>
public abstract class XamarinFormsActivity<TPage> : AppCompatActivity
    where TPage : ContentPage, new()
{
    protected readonly TPage _page;
    protected int _containerLayoutId = Resource.Layout.activity_fragment_container;
    public Android.Support.V7.Widget.Toolbar Toolbar { get; set; }
    public AppBarLayout AppBar { get; set; }

    public XamarinFormsActivity()
    {
        _page = new TPage();
    }

    /// <summary>
    /// Creates the activity and maps the Xamarin.Forms page to the fragment
    /// </summary>
    /// <param name="savedInstanceState">Saved instance state.</param>
    protected override void OnCreate(Android.OS.Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.xamarin_forms_activity);

        Toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
        if (Toolbar?.Parent != null)
        {
            AppBar = Toolbar?.Parent as AppBarLayout;
            SetSupportActionBar(Toolbar);
        }

        // register the fragment
        var transaction = SupportFragmentManager.BeginTransaction();
        transaction.Add(Resource.Id.fragment_container, _page.CreateSupportFragment(this));
        transaction.Commit();
        SupportActionBar?.SetDisplayHomeAsUpEnabled(true);
        SupportActionBar?.SetDisplayShowHomeEnabled(true);
        Toolbar?.SetBackgroundColor(Android.Graphics.Color.White);
        // everything else from this point should be managed by the Xamarin.Forms page behind the fragment
    }
}

So now we can create a simple Xamarin.Forms page:

SomePage.xaml

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"     x:Class="MyApp.Pages.SomePage">
    <ContentPage.Content>
        <Grid>
            <Label Text="I'm Embedded!" HorizontalOptions="Center" VerticalOptions="Center"/>
        </Grid>
    </ContentPage.Content>
</ContentPage>

Then create the associated Activity:

SomeActivity.cs

public class SomeActivity : XamarinFormsActivity<SomePage>
{
    protected override void OnCreate(Bundle savedInstance)
    {
        SupportActionBar.Title = "Some Page";
    }
}

Now all we have to do is kick off this SomeActivity after calling Xamarin.Forms.Init() and we are good to go! If we have a MainActivity we can call it before navigating if it isn’t initialized, or execute it in OnResume or a similar lifecycle event.

MainActivity.cs

public class MainActivity : AppCompatActivity 
{    

    protected override void OnCreate(Bundle savedInstance)
    {
        base.OnCreate(savedInstance);
        SetContentView(Resource.Layout.main_activity);
        var someButton = FindViewBy<Button>(Resource.Id.some_button);
        someButton.Click += delegate 
        {
             if(!Xamarin.Forms.Forms.IsInitialized)
                 Xamarin.Forms.Forms.Init(this, savedInstance);
             StartActivity(typeof(SomeActivity));
        }
    } 
}

And there you have it! Some new Xamarin.Forms embedding for performance and other extra benefits 🙂

In future posts of this subject, we’ll look at the same setup for iOS, extending interactions between the Xamarin.Forms Page and the native Activity and ViewControllers, using advanced native components with the embedded Xamarin.Forms Page, and more!

Let me know what you think of this pattern – have you used it? What else would you want to hear about it??

Be sure to checkout some of the Xamarin examples on embedding too!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Adding a File Upload Field to Your Swagger UI With Swashbuckle

If you’re building ASP.NET Core Web APIs, then I hope you’ve heard of Swashbuckle – the tool to generate the Swagger UI automatically for all of your controllers to make manual testing your endpoints visual and simple.

Out of the box, the documentation helps you set up your UI, handle different ways to authenticate (which we will touch on in a later post), and have it all hooked up to your controllers. However, this only handles the most common cases of required requests with query string parameters and HTTP Body content.

In this post, we’ll look at a quick and easy way to also add File upload fields for your API endpoints that consume IFormFile properties to make testing file uploading even easier.

Basic Swagger Setup

First thing’s first, install that puppy:

Package Manager : Install-Package Swashbuckle.AspNetCore
CLI : dotnet add package Swashbuckle.AspNetCore

Let’s first look at a simple swagger setup as our baseline before we add everything for our HTTP Header Field.

Startup.cs

//...
public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddSwaggerGen(config =>
    {
        config.SwaggerDoc("v1", new Info { Title = "My API", Version = "V1" });
    });
    // ...
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // ...
    app.UseMvc();

    app.UseSwagger();
    app.UseSwaggerUI(config =>
    {
        config.SwaggerEndpoint("/swagger/v1/swagger.json", "My API v1");
    });
    // ...
}
//...

This setup gives us all we need for our basic UI and wireup to our controllers!
Running this gives us our basic swagger at /swagger:
Swagger no header

Adding a File Upload Field

What we have to do now is add an OperationFilter to our swagger generation. These OperationFilters can do a whole lot and enable us to customize the swagger document created which is what drives the fields and info on the UI.

Let’s start by creating our FormFileSwaggerFilter class.

FormFileSwaggerFilter.cs

/// <summary>
/// Filter to enable handling file upload in swagger
/// </summary>
public class FormFileSwaggerFilter : IOperationFilter
{
    private const string formDataMimeType = "multipart/form-data";
    private static readonly string[] formFilePropertyNames =
        typeof(IFormFile).GetTypeInfo().DeclaredProperties.Select(p => p.Name).ToArray();

    public void Apply(Operation operation, OperationFilterContext context)
    {
        var parameters = operation.Parameters;
        if (parameters == null || parameters.Count == 0) return;

        var formFileParameterNames = new List<string>();
        var formFileSubParameterNames = new List<string>();

        foreach (var actionParameter in context.ApiDescription.ActionDescriptor.Parameters)
        {
            var properties =
                actionParameter.ParameterType.GetProperties()
                    .Where(p => p.PropertyType == typeof(IFormFile))
                    .Select(p => p.Name)
                    .ToArray();

            if (properties.Length != 0)
            {
                formFileParameterNames.AddRange(properties);
                formFileSubParameterNames.AddRange(properties);
                continue;
            }

            if (actionParameter.ParameterType != typeof(IFormFile)) continue;
            formFileParameterNames.Add(actionParameter.Name);
        }

        if (!formFileParameterNames.Any()) return;

        var consumes = operation.Consumes;
        consumes.Clear();
        consumes.Add(formDataMimeType);

        foreach (var parameter in parameters.ToArray())
        {
            if (!(parameter is NonBodyParameter) || parameter.In != "formData") continue;

            if (formFileSubParameterNames.Any(p => parameter.Name.StartsWith(p + "."))
                || formFilePropertyNames.Contains(parameter.Name))
                parameters.Remove(parameter);
        }

        foreach (var formFileParameter in formFileParameterNames)
        {
            parameters.Add(new NonBodyParameter()
            {
                Name = formFileParameter,
                Type = "file",
                In = "formData"
            });
        }
    }
}

This operation filter takes the operation parameters, then uses reflection to find the type of the field. If the field is an IFormFile, then we add a new file field from the formData section to our parameters. This in turn will update our swagger definition json file, and when rendered adds the field to our UI.

This even works great with endpoints that take a separate HTTP Body, query parameters, and files!

Now we need to reference it in our Startup when we initialize swagger:

Startup.cs

//...
public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddSwaggerGen(config =>
    {
        config.SwaggerDoc("v1", new Info { Title = "My API", Version = "V1" });

        config.OperationFilter<FormFileSwaggerFilter>();
    });
    // ...
}

Here’s an example controller with an endpoint that uses the file upload:

FileUploadController

[Route("api/[controller]")]
public class FileUploadController : Controller
{
    [HttpPost]
    public async Task<IActionResult> CreateMediaItem(string name, [FromForm]IFormFile file)
    {
        // Do something with the file
        return Ok();
    }
}

This controller ends up rendering in our Swagger UI as:
Fileupload_swagger

And using this, we can now submit our request with an uploaded file and all our other parameters!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Adding a Required HTTP Header to Your Swagger UI With Swashbuckle

If you’re building ASP.NET Core Web APIs, then I hope you’ve heard of Swashbuckle – the tool to generate the Swagger UI automatically for all of your controllers to make manual testing your endpoints visual and simple.

Out of the box, the documentation helps you set up your UI, handle different ways to authenticate (which we will touch on in a later post), and have it all hooked up to your controllers. However, this only handles the most common cases of required requests with query string parameters and HTTP Body content.

In this post, we’ll look at a quick and easy way to also add fields for your custom HTTP Request Headers so you can fill them out while testing without having to do some funky stuff in the console.

Basic Swagger Setup

First thing’s first, install that puppy:

Package Manager : Install-Package Swashbuckle.AspNetCore
CLI : dotnet add package Swashbuckle.AspNetCore

Let’s first look at a simple swagger setup as our baseline before we add everything for our HTTP Header Field.

Startup.cs

//...
public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddSwaggerGen(config =>
    {
        config.SwaggerDoc("v1", new Info { Title = "My API", Version = "V1" });
    });
    // ...
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // ...
    app.UseMvc();

    app.UseSwagger();
    app.UseSwaggerUI(config =>
    {
        config.SwaggerEndpoint("/swagger/v1/swagger.json", "My API v1");
    });
    // ...
}
//...

This setup gives us all we need for our basic UI and wireup to our controllers!
Running this gives us our basic swagger at /swagger:
Swagger no header

Adding Custom Headers

What we have to do now is add an OperationFilter to our swagger generation. These OperationFilters can do a whole lot and enable us to customize the swagger document created which is what drives the fields and info on the UI.

Let’s create a MyHeaderFilter and then add it to the AddSwaggerGen call.

MyHeaderFilter.cs

/// <summary>
/// Operation filter to add the requirement of the custom header
/// </summary>
public class MyHeaderFilter : IOperationFilter
{
    public void Apply(Operation operation, OperationFilterContext context)
    {
        if (operation.Parameters == null)
            operation.Parameters = new List<IParameter>();

        operation.Parameters.Add(new NonBodyParameter
        {
            Name = "MY-HEADER",
            In = "header",
            Type = "string",
            Required = true // set to false if this is optional
        });
    }
}

And now we need to update our Startup class:

Startup.cs

//...
public void ConfigureServices(IServiceCollection services)
{
    // ...
    services.AddSwaggerGen(config =>
    {
        config.SwaggerDoc("v1", new Info { Title = "My API", Version = "V1" });

        config.OperationFilter<MyHeaderFilter>();
    });
    // ...
}

Now when we run and navigate to our /swagger url, we can see:
Swagger with header

When we fill out that field, we can now pull the value off the request header in our controller!

ContentController.cs

[Route("api/[controller]")]
public class ContentController : Controller
{
    public void Search([FromBody]InputModel model)
    {
        Console.WriteLine(Request.Headers["MY-HEADER"]);        
    }
}

In further posts, we’ll talk about adding Bearer Authentication, XML Comments, and More 🙂


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.