限制 OData 如何导致 WebAPI

Question

I'm currently developing an application which uses a Web API to return data which is stored in a database.

Now, I need to be able to filter the results, so OData to the request, that way I can built an entire filter in a query string.

Here's the configuration of the OData:

private static void ConfigureOData(HttpConfiguration config)
{
    ODataModelBuilder builder = new ODataConventionModelBuilder();
    builder.EntitySet<GenericArticle>("GenericArticle");
    config.MapODataServiceRoute(routeName: "ODataRoute", routePrefix: "OData", model: builder.GetEdmModel());

    // Defines the configuration for OData.
    var queryAttribute = new QueryableAttribute
    {
        MaxTop = Convert.ToInt32(ConfigurationManager.AppSettings["OData:MaxTop"]),
        PageSize = 2
    };

    config.EnableQuerySupport(queryAttribute);
}

This method is being called from within the WebApiConfig.cs file.

The Global.asax file does contain the following code:

protected void Application_Start()
{
    GlobalConfiguration.Configure(WebApiConfig.Register);
    GlobalConfiguration.Configuration.EnsureInitialized();

    UpdateDatabaseToLatestVersion();
}

The controller that I use to query the data is the following:

 [EnableQuery]
 public IQueryable<GenericArticle> Get()
 {
     var data = UnitOfWork.GenericArticlesRepository.Entities;

     return data;
 }

So, the method is marked with the EnableQuery attribute and the controller does also inherit from ODataController .

Now, there are some tables which I can query which contains millions of records, and off course, I don't even want a GetAll to find it's way to the database.

Therefore, I tought that in the WebApiConfig file, the following code was sufficient:

var queryAttribute = new QueryableAttribute
{
    MaxTop = Convert.ToInt32(ConfigurationManager.AppSettings["OData:MaxTop"]),
    PageSize = 2
};

However, this does not limit the results, but it throws an error when I request the url with a take filter which is more than the MaxTop value defined here.

Is there a way to ensure that, even if I request the url without any filter parameters, that the result will only contain the first 'x' records with paging enabled?

Answer 1

Please try server paging option to filter the records in case if you want to restrict the number of records fetching.

Check this link - http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/supporting-odata-query-options#server-paging