Eric lippert - Amazon Web Services

{
private TimeKeeprContext db = new TimeKeeprContext();
// GET api/TimeCard
public IEnumerable GetTimeCards()
{
return db.TimeCards.AsEnumerable();
}
// GET api/TimeCard/5
public TimeCard GetTimeCard(int id)
{
TimeCard timecard = db.TimeCards.Find(id);
if (timecard == null)
{
throw new HttpResponseException(Request.
CreateResponse(HttpStatusCode.NotFound));
}
return timecard;
}
…
}
}
Custom Media Type
Formatters and
Content Types
Thus, we’ve seen how the out of the box media formatters work,
let’s see what options we have for formatting data with a custom
media formatter.
Use Case
The information we have can be easily saved as Calendar items.
So it would be nice if our service could serve up VCalendar items
too. VCalendar is a data format that most calendaring tools
support. If our Web API could serve up VCalendar items for each
TimeCard, then they could be easily integrated with calendaring
tools like Outlook.
With this use case in mind, let’s create a
VCalendarMediaTypeFormatter.
Our Custom Media Type
Formatter
Custom Media Type Formatters subclass the
MediaTypeFormatter abstract class or one of its
implementations. We will subclass the
BufferedMediaTypeFormatter.
public class VCalendarMediaTypeFormatter :
BufferedMediaTypeFormatter
{
…
}
First thing we do in the constructor is to clear out all Supported
media types and only keep “text/calendar”, which is the standard
header type for requesting calendar items.
public VCalendarMediaTypeFormatter()
{
SupportedMediaTypes.Clear();
SupportedMediaTypes.Add(new MediaTypeHeaderValue(“text/
calendar”));
}
Next we override the SetDefaultContentHeaders and set
content-disposition as an attachment with a generic file name
(myFile.ics).
public override void SetDefaultContentHeaders(Type type,
HttpContentHeaders headers, MediaTypeHeaderValue
mediaType)
{
headers.Add(“content-disposition”, (new
ContentDispositionHeaderValue(“attachment”) {
FileName = “myfile.ics” }).ToString());
base.SetDefaultContentHeaders(type, headers,
mediaType);
}
Since our formatter will not be accepting ICS files in posts, we’ll
override the CanReadType method and return false directly.
public override bool CanReadType(Type type)
{
return false;
}
Our Formatter should only try to format requests of type
TimeCard and not any other type. So we limit this in the
CanWriteType method by checking if the incoming type is of type
TimeCard only.
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