Accessing the query string in ASP.Net Web Api?

Even though @Kiran Challa's answer is correct, there are few situations that you might prefer to get URL parameters directly from the URL. in those scenarios, try this:

using System.Net.Http;

var allUrlKeyValues = ControllerContext.Request.GetQueryNameValuePairs();

string p1Val = allUrlKeyValues.LastOrDefault(x => x.Key == "p1").Value;
string p2Val = allUrlKeyValues.LastOrDefault(x => x.Key == "p2").Value;
string p3Val = allUrlKeyValues.LastOrDefault(x => x.Key == "p3").Value;

Now for the following URL, p1Val will be "Apple", p2Val will be "Banana", and p3Val will be null.

.../api/myController?p1=Apple&p2=Banana

Update:

Thanks for the suggestions, now, the source code for this test is in GitHub and it also runs and can be tested on Azure:

• http://freewebapi.azurewebsites.net/api/values?p1=Apple&p2=Banana

The query string key name should match the parameter name of the action:

/api/values?queryString=f

public IEnumerable<string> Get(string queryString)
    {
        return new string[] { "value3", "value4" };
    }

There is one more way to get query string as shown below when you are using wildcard in route or for dynamic routes.

string query = ControllerContext.HttpContext.Request.QueryString.Value;

BONUS:)

string path = ControllerContext.HttpContext.Request.Path.ToUriComponent();