Returning IHttpActionResult vs IEnumerable<Item> vs IQueryable<Item>
Solution 1
You should return IHttpActionResult
because you can be more specific to the client. You can create more user friendly web applications. Basically you can return different HTML status messages for different situations.
For example:
public async Task<IHttpActionResult> GetMyItems()
{
if(!authorized)
return Unauthorized();
if(myItems.Count == 0)
return NotFound();
//... code ..., var myItems = await ...
return Ok(myItems);
}
IEnumerable
and IQueryable
will just parse your data into the output format and you will not have a proper way to handle exceptions. That is the most important difference.
Solution 2
I would choose between IEnumerable and IHttpActionResult, you can do pretty much the same thing with both of these just in slightly different ways. IQueryable is usually used for lower level data access tasks and deferred execution of sql queries so I'd keep it encapsulated within your data access classes and not expose it with the web api.
Here's a summary from http://www.asp.net/web-api/overview/web-api-routing-and-actions/action-results:
IHttpActionResult
The IHttpActionResult interface was introducted in Web API 2. Essentially, it defines an HttpResponseMessage factory. Here are some advantages of using the IHttpActionResult interface (over the HttpResponseMessage class):
- Simplifies unit testing your controllers.
- Moves common logic for creating HTTP responses into separate classes.
- Makes the intent of the controller action clearer, by hiding the low-level details of constructing the response.
IEnumerable<Item>
For all other return types, Web API uses a media formatter to serialize the return value. Web API writes the serialized value into the response body. The response status code is 200 (OK).
public class ProductsController : ApiController
{
public IEnumerable<Product> Get()
{
return GetAllProductsFromDB();
}
}
A disadvantage of this approach is that you cannot directly return an error code, such as 404. However, you can throw an HttpResponseException for error codes. For more information.
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Adam Szabo
Updated on June 05, 2022Comments
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Adam Szabo about 2 years
In ASP.NET Web API 2, what is the difference among the following?
public async Task<IEnumerable<MyItem>> GetMyItems() { //... code ..., var myItems = await ... return myItems; }
and
public async Task<IQueryable<MyItem>> GetMyItems() { //... code ..., var myItems = await ... return myItems; }
and
public async Task<IHttpActionResult> GetMyItems() { //... code ..., var myItems = await ... return Ok(myItems); }
Should I return
IHttpActionResult
orIEnumerable<MyItem>
/IQueryable<MyItem>
? -
Aron almost 10 years-1 "IQueryable is usually used for lower level data access tasks and deferred execution of sql queries so I'd keep it encapsulated within your data access classes and not expose it with the web api." This is completely wrong. Without exposing IQueryable, it is difficult to use
OData
query urls. asp.net/web-api/overview/odata-support-in-aspnet-web-api/… -
Jason Watmore almost 10 years@Aron I agree this doesn't apply to OData, but a lot of people would disagree with you about exposing IQueryable outside of the repository layer: codetunnel.com/…, programmers.stackexchange.com/questions/192044/…, mikehadlow.blogspot.com.au/2009/01/…. And some people even describe OData itself as an anti-pattern github.com/ServiceStack/ServiceStack/wiki/…
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Aron almost 10 yearsThose are the same people i would argue that inner platform is an anti pattern.
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Jason over 9 years+1 I am looking to implement OData urls and your answer lead me down the right path for error handling. HttpResponseException is what I needed. Thanks!
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DavidRR over 6 yearsGiven that
await
is not used withinGetMyItems()
, its signature should simply bepublic IHttpActionResult GetMyItems()
. From the question IHttpActionResult vs async Task<IHttpActionResult>, see this answer which states: "If your controller action code doesn't useawait
then you can switch back to the simpler signature. However, the result you return will still be asynchronous." -
Conner about 5 yearsI would not use IEnumerable if you have an exception filter neovolve.com/2013/02/20/…
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AceMark almost 4 yearsI am here to say that the "...throw an HttpResponseException ..." is what I needed. Thanks @Jason