How can I get a list of available methods in a WebAPI web service?

Question

I'm building a small test tool that should provide the user a list of web services (built using WebAPI). The user should be able to choose a service to test. I'm using

HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://'localhost':51062/");

// Add an Accept header for JSON format.

client.DefaultRequestHeaders.Accept.Add(
                new MediaTypeWithQualityHeaderValue("application/json"));

and am looking for something like

client.GetAllWebServices()

which would return a list of methods that the user can see. Meaning, the methods that he developed on the controller and wants to test.

Answer 1

Michael was correct to mention ApiExplorer. This gives you details of all the WebApi methods for you. You just need to format it how you want the response.

Here is a simple example to get a list of all the methods with their parameters and return types. You can of course make this much more comprehensive - just browse the objects to find what you need:

using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using System.Web.Http.Description;

namespace WebApplication1.Controllers
{
    public class ApiMethodController : ApiController
    {
        public IEnumerable<HelpMethod> GetMethods()
        {
            // get the IApiExplorer registered automatically
            IApiExplorer ex = this.Configuration.Services.GetApiExplorer();

            // loop, convert and return all descriptions 
            return ex.ApiDescriptions
                // ignore self
                .Where(d => d.ActionDescriptor.ControllerDescriptor.ControllerName != "ApiMethod")
                .Select(d =>
                {
                    // convert to a serializable structure
                    return new HelpMethod
                    {
                        Parameters = d.ParameterDescriptions.Select(p => new HelpParameter
                        {
                            Name = p.Name,
                            Type = p.ParameterDescriptor.ParameterType.FullName,
                            IsOptional = p.ParameterDescriptor.IsOptional
                        }).ToArray(),
                        Method = d.HttpMethod.ToString(),
                        RelativePath = d.RelativePath,
                        ReturnType = d.ResponseDescription.DeclaredType == null ?
                            null : d.ResponseDescription.DeclaredType.ToString()
                    };
                });
        }
    }

    public class HelpMethod
    {
        public string Method { get; set; }
        public string RelativePath { get; set; }
        public string ReturnType { get; set; }
        public IEnumerable<HelpParameter> Parameters { get; set; }
    }

    public class HelpParameter
    {
        public string Name { get; set; }
        public string Type { get; set; }
        public bool IsOptional { get; set; }
    }
}

The nice thing is that it is a WebApi call itself, so you can use the HttpClient to call and process it using http://www.localhost.com/api/ApiMethod/Methods. Here's a sample JSON response:

[
    {
        "Method": "GET",
        "RelativePath": "api/Account/{id}",
        "ReturnType": "WebApplication1.Models.Account",
        "Parameters": [
            {
                "Name": "id",
                "Type": "System.Int32",
                "IsOptional": false
            }
        ]
    },
    {
        "Method": "POST",
        "RelativePath": "api/Account",
        "ReturnType": null,
        "Parameters": [
            {
                "Name": "a",
                "Type": "WebApplication1.Models.Account",
                "IsOptional": false
            }
        ]
    },
    {
        "Method": "GET",
        "RelativePath": "api/Maths?i={i}&j={j}",
        "ReturnType": "System.Int32",
        "Parameters": [
            {
                "Name": "i",
                "Type": "System.Int32",
                "IsOptional": false
            },
            {
                "Name": "j",
                "Type": "System.Int32",
                "IsOptional": false
            }
        ]
    }
]

Going Forward

Getting XML doc comments out isn't so clear cut, but there is a tutorial on MSDN Blogs.

Also, there are other packages available which you can use, hook into, steal from, which do similar to what you need, for example

• Swagger.Net
• RAML

More details on these in VS Mag