Web API QueryString没有将第二个参数传递给控制器​​/操作

Question

I have a Web API application which is expected to return a list of clinical alerts for patients. The request is invoked with the following URL

http://myserver:18030/api/Alerts/search?systemId=182&patientId=T000282L

where the systemId determines the clinical information system for which the patientID value is relevant. The routing is set up as follows in WebApiConfig.cs

public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
           name: "Alertsapi",
           routeTemplate: "api/Alerts/search",
           defaults: new { controller = "Alerts" , action = "search"}
       );

and the controller actions is as follows:

    [ActionName("search")]
    public  List<Alert> GetAlerts(string systemId = "", string patientId = "")
    {
        var alerts = from a in db.Alerts
                    where a.alertAuthorReference.Equals(systemId)
                    where a.alertSubjectReference.Equals(patientId)
                    select a;
        return alerts.ToList();
    }

I was under the impression that QueryString parameters where automatically mapped to action method parameters, but in this example patientId is always null (or an empty string as I am supplying that as a default). I have tried reading the QueryString in code inside the action method, but it only has one member with key systemId.

Why isn't the second parameter being passed through?

I can work around it by using a QueryString of patientId=182:T000282L and then parsing this composite key, but I want to be able eventually to search on multiple parameters, and so may need to access a third or even fourth value from the query string.

Answer 1

You need to define a route for that like

 routes.MapHttpRoute(
             name: "GetPagedData",
             routeTemplate: "api/{controller}/{action}/{pageSize}/{pageNumber}"
        )

your controller will be like

[HttpGet]
("GetPagedResult")]
HttpResponseMessage GetPagedResult(int StartIndex, int PageSize)
{
         // you can set default values for these parameters like StartIndex = 0 etc.
}

Answer 2

You can easily get what you need now with Web API 2 and Attribute Routing.

Take a look at this article:

http://www.asp.net/web-api/overview/web-api-routing-and-actions/attribute-routing-in-web-api-2

First you'll need to edit WebApiConfig.cs

    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services

        // Web API routes
        config.MapHttpAttributeRoutes();

[...]

in your case you can test it works with this inside a controller:

    [Route("search")]
    [HttpGet]
    public string search(string systemId = "", string patientId = "")
    {

        return patientId;
    }

and to call it:

http://myserver:18030/search?systemId=182&patientId=T000282L