Proper approach to create hypermedia in c# webapi

Question

I'm doing some research on how to implement hypermedia for a particular resource, but can't find a real implementation example, just abstractions...

You know, in various articles, the guy create a method like:

public List<Link> CreateLinks(int id)
{
    ...//Here the guy put these three dots, whyyyyyyyyyy?
}

What I have so far:

public Appointment Post(Appointment appointment)
    {
        //for sake of simplicity, just returning same appointment
        appointment = new Appointment{
            Date = DateTime.Now,
            Doctor = "Dr. Who",
             Slot = 1234,
            HyperMedia = new List<HyperMedia>
            {
                new HyperMedia{ Href = "/slot/1234", Rel = "delete" },
                new HyperMedia{ Href = "/slot/1234", Rel = "put" },
            }
        };

        return appointment;
    }

And the Appointment class:

public class Appointment
{
    [JsonProperty("doctor")]
    public string Doctor { get; set; }

    [JsonProperty("slot")]
    public int Slot { get; set; }
    [JsonProperty("date")]
    public DateTime Date { get; set; }

    [JsonProperty("links")]
    public List<HyperMedia> HyperMedia { get; set; }
}

public class HyperMedia
{
    [JsonProperty("rel")]
    public string Rel { get; set; }

    [JsonProperty("href")]
    public string Href { get; set; }
}

Is there a proper way to that? I mean, without hard coding the links? How to create them dynamically for a given type, i.e. Appointment class?

I'm using c# Webapi, not c# MVC.

Answer 1

1. For adding routes dynamically to the HyperMedia collection you can make use of route naming:

   • Define your route with a specific name (for example for deletion):

     [Route("{id:int}", Name = "AppointmentDeletion")]
     public IHttpActionResult Delete(int slot)
     {
         //your code
     }
     

   • Use it by UrlHelper.Link method:

     public Appointment Post(Appointment appointment)
     {
         appointment = new Appointment
         {
             HyperMedia = new List<HyperMedia>
             {
                 new HyperMedia
                 { 
                     Href = Url.Link("AppointmentDeletion", new { slot = 1234 }), 
                     Rel = "delete" 
                 }
             }
     
         return appointment;
     }; 
     

2. It is also possible to add links dynamically to a result object without declaring the HyperMedia property for every class:

   • Define a class without links:

     public class Appointment
     {
         [JsonProperty("doctor")]
         public string Doctor { get; set; }
     
         [JsonProperty("slot")]
         public int Slot { get; set; }
     
         [JsonProperty("date")]
         public DateTime Date { get; set; }
     } 
     

   • Define an extension method:

     public static class LinkExtensions
     {
         public static dynamic AddLinks<T>(this T content, params object[] links)
         {
             IDictionary<string, object> result = new ExpandoObject();
     
             typeof (T)
                 .GetProperties(BindingFlags.Public | BindingFlags.Instance)
                 .ToList()
                 .ForEach(_ => result[_.Name.ToLower()] = _.GetValue(content));
     
             result["links"] = links;
     
             return result;
         }
     }
     

   • Use it:

     public IHttpActionResult Post(Appointment appointment)
     {
         return Ok(appointment.AddLinks(new HyperMedia
         { 
             Href = Url.Link("AppointmentDeletion", new { slot = 1234 }), 
             Rel = "delete" 
         }));
     }