ASP.NET and static method in controller

Question

Assume that WebApi2 controller has a SearchClient which is configured in scoped-lifestyle dependency on startup.

public class SearchController : ApiController {

    private readonly SearchClient _indexClient;

    public SearchController(SearchClient client) {
        _indexClient = client; // dependency injected
    }

    public IEnumerable<string> Get(string keyword){
        return SearchDocuments(_indexClient, keyword);
    }

    public static IEnumerable<string> SearchDocuments(SearchClient indexClient, string text)
    {
        return indexClient.Search(text);
    }
}

As we can see, SearchDocuments method has static keyword.

My questions are;

1. How can we decide whether static method is good or bad?
2. Is static method safe or recommended in such a multiple-accessed web environment?
3. What about async static method in web environment? Is it different from async method?

Answer 1

How can we decide whether static method is good or bad?

Static methods in web applications are just like static methods in desktop applications. There is no difference in how they are handled or interpreted once they run in a web application. So they are not bad or good, you use them for everything that is not instance-specific.

Is static method safe or recommended in such a multiple-accessed web environment?

static fields or properties can have unwanted side effects when user or session specific data is stored in it since static variables are shared across sessions. But this is a method, and methods don't have a shared state. Hence they are safe to use in a multi-user/multi-session environment.

What about async static method in web environment? Is it different from async method?

Nothing other than already described in the answer to your first question.