ASP.net MVC 4 (web api) OData Configuration

Question

Been playing around with the (Single Page App) BigShelf sample. I found really interesting is the GetBooksForSearch method (/api/BigShelf/GetBooksForSearch) that it takes additional $filter, $inlinecount, $top, $skip parameters for paging and filtering results, which are not present in the controller code:

public IQueryable<Book> GetBooksForSearch
    (string profileIds, Sort sort, bool sortAscending)

I coudln't find any documents about how that Controller translate and filter the result afterwards and more importantly, how to configure such behavior (e.g., limit the max result), anyone have a clue?

-- Updated --

Found out that MVC Web API is doing the trick. But how can we configure it?

Cody Clark · Accepted Answer · 2012-11-16 20:05:31Z

14

It appears that the ResultLimitAttribute has been removed. See this commit

It was rolled into a feature of the [Queryable] attribute which is now required for OData support. See discussion here

Proper Usage would now be

[Queryable(ResultLimit = 10)]

[UPDATE]

As of RTM the ResultLimit feature of Queryable has been removed. Also, [Queryable] has been moved to it's own preview package. See this blog post for more information and this post for instructions on the new usage.

[UPDATE 2 11-16-12] With the ASP.Net Fall 2012 Update Preview things have been updated again. The ResultLimit Property of The [Queryable] attribute has been added back to the OData package.

See article here for a run down of some of the changes.

Here is the updated Nuget package. As of this writing it is a PREVIEW package.

edited Nov 16, 2012 at 20:05

answered Aug 14, 2012 at 19:41

Cody Clark

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1 Comment

Jim Wooley Over a year ago

It looks like ResultLimit was removed by the 5.2 official release. This is now found in EnableQueryAttribute for PageSize.

marcind · Accepted Answer · 2012-02-22 03:29:52Z

11

There's an action filter attribute called ResultLimitAttribute which you can use on any action method which returns IQueryable<T> or even IEnumerable<T> to limit the amount of data returned.

[ResultLimit(100)]
public IQueryable<Product> Get() {
    // ...
}

edited Feb 22, 2012 at 3:29

answered Feb 21, 2012 at 17:21

marcind

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3 Comments

xandy Over a year ago

This (msdn.microsoft.com/en-us/library/…) seems to be a new Filter, and I guess this is designed for the new framework and exactly what I want..

Luke Puplett Over a year ago

Is there an alternative to using an Attribute? It's just that the number can't be pulled from config since Attributes must use constants.

marcind Over a year ago

@LukePuplett you could try to write a filter attribute that pulls the value from config

Robert Levy · Accepted Answer · 2012-02-21 20:44:35Z

3

There is a short webcast about paging and querying with MVC Web API that you can watch here

It explains how you can perform paging by either

using the OData query syntax, in which case the Web API automatically interprets and retrieves the results for you,
or by writing your own method which takes as parameters the pageIndex and pageSize, and then returns the requested number of items.

AFAIK, you cannot configure the maximum number of items returned by using the first method, but you could limit the number of items returned by using the second approach, and just checking if (pageSize>maxPage) then return maxPage items.

edited Feb 21, 2012 at 20:44

Robert Levy

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answered Feb 21, 2012 at 9:08

Szilard Muzsi

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2 Comments

Robert Levy Over a year ago

There is secret fairy dust under the covers with option 1. You can just as easily write your own method that only loads the necessary data. With option 1, the framework is just going to call .Take, .Skip, etc on the IQueryable you return

xandy Over a year ago

@RobertLevy, doing .Take on the IQueryable return is not a good idea, since OData also defines filtering operations. That would makes IQueryable.Take(n).filter() instead of IQueryable.filter().Take(n)

Jim Wooley · Accepted Answer · 2014-09-09 03:27:03Z

As Cody Clark pointed out, this area has seen quite a number of changes over time. As of the 5.2 version of WebAPI, you now use the EnableQueryAnnotation and use the PageSize parameter rather than QueryableAttribute or ResultLimit. ([Queryable] will still work, but it is marked as obsolete.) Currently you would use the following syntax:

[EnableQuery(PageSize = 20, MaxTop = 20)]
public IQueryable<Product> Get() {
    // ...
}

By using PageSize, you set the default page size for unparameterized requests. If you don't include the MaxTop value, a rogue client could set the top to a very high value and bypass the page defaults. With MaxTop, you will throw an exception if the client requests more records than your API supports.

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