Pass an array of integers to ASP.NET Web API?

Question

I have an ASP.NET Web API (version 4) REST service where I need to pass an array of integers.

Here is my action method:

Answer 1

I originally used the solution that @Mrchief for years (it works great). But when when I added Swagger to my project for API documentation my end point was NOT showing up.

It took me a while, but this is what I came up with. It works with Swagger, and your API method signatures look cleaner:

In the end you can do:

    // GET: /api/values/1,2,3,4 

    [Route("api/values/{ids}")]
    public IHttpActionResult GetIds(int[] ids)
    {
        return Ok(ids);
    }

WebApiConfig.cs

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Allow WebApi to Use a Custom Parameter Binding
        config.ParameterBindingRules.Add(descriptor => descriptor.ParameterType == typeof(int[]) && descriptor.ActionDescriptor.SupportedHttpMethods.Contains(HttpMethod.Get)
                                                           ? new CommaDelimitedArrayParameterBinder(descriptor)
                                                           : null);

        // Allow ApiExplorer to understand this type (Swagger uses ApiExplorer under the hood)
        TypeDescriptor.AddAttributes(typeof(int[]), new TypeConverterAttribute(typeof(StringToIntArrayConverter)));

        // Any existing Code ..

    }
}

Create a new class: CommaDelimitedArrayParameterBinder.cs

public class CommaDelimitedArrayParameterBinder : HttpParameterBinding, IValueProviderParameterBinding
{
    public CommaDelimitedArrayParameterBinder(HttpParameterDescriptor desc)
        : base(desc)
    {
    }

    /// 

    /// Handles Binding (Converts a comma delimited string into an array of integers)
    /// 
    public override Task ExecuteBindingAsync(ModelMetadataProvider metadataProvider,
                                             HttpActionContext actionContext,
                                             CancellationToken cancellationToken)
    {
        var queryString = actionContext.ControllerContext.RouteData.Values[Descriptor.ParameterName] as string;

        var ints = queryString?.Split(',').Select(int.Parse).ToArray();

        SetValue(actionContext, ints);

        return Task.CompletedTask;
    }

    public IEnumerable ValueProviderFactories { get; } = new[] { new QueryStringValueProviderFactory() };
}

Create a new class: StringToIntArrayConverter.cs

public class StringToIntArrayConverter : TypeConverter
{
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
    }
}

Notes:

• https://stackoverflow.com/a/47123965/862011 pointed me in the right direction
• Swagger was only failing to pick my comma delimited end points when using the [Route] attribute