异步任务缺少对MVC IHttpActionResult控制器的等待

Question

I am using an async task to return Json data that I modeled using a data dictionary. I want the task to execute asynchronously while it does my database calls in from my methods report.GetActiveBuildDefinitions() and my object of CurrentState which has a constructor which gets the data i need. This is the constructor I am talking about -> new CurrentState(BuildDef.ID); This controller functions properly. But when i enable Warnings as Errors. My class does not build. It requires that I use the await keyword for my async task. I tried adding it to the return like return await Json(state); but then it gives an error that "does not contain a definition for getawaiter" please help

This is my controller:

        [HttpGet]
    public async Task<IHttpActionResult> GetBuildState()
    {
        try
        {
            List<CurrentState> state = new List<CurrentState>();
            BuildReport report = new BuildReport();
            List<BuildDefinition> definitions = report.GetActiveBuildDefinitions();
            List<Dictionary<string, string>> buildInfo = new List<Dictionary<string, string>>();

            foreach (BuildDefinition BuildDef in definitions)
            {
                state.Add(new CurrentState(BuildDef.ID));
            }

            foreach (CurrentState build in state)
            {
                Dictionary <string, string> entry = new Dictionary<string, string>();
                if (build.ITestExists)
                {
                    if (build.ITestState && build.BuildState)
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "1");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "1");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }
                    else if(build.BuildState && build.ITestState.Equals(false))
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "2");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "0");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }
                    else if (build.BuildState.Equals(false) && build.ITestState)
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "3");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "0");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }
                    else if (build.ITestState.Equals(false) && build.BuildState.Equals(false))
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "0");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "0");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }

                }
                else
                {
                    if (build.BuildState)
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "4");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "1");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }
                    else
                    {
                        entry.Add("BuildDef", build.BuildDefName);
                        entry.Add("GraphCode", "5");
                        entry.Add("WorkingBrokenTime", GetTime(build.BuildDefID));
                        entry.Add("Icon", "0");
                        entry.Add("Id", build.BuildDefID.ToString());
                    }
                }
                buildInfo.Add(entry);
            }
            return Json(state);
        }
        catch (Exception)
        {
            return BadRequest(ModelState);
        }
    }

Answer 1

I want the task to execute asynchronously

But why? What benefit do you think asynchrony will get you, here?

Hint: async does not mean "return early".

Everything currently in your controller action is synchronous, so your controller action should be synchronous, too:

public IHttpActionResult GetBuildState()

Now, if you change your I/O calls to be naturally asynchronous (ie, using EF6 asynchronous queries), then your controller action may end up calling an asynchronous method:

var definitions = await report.GetActiveBuildDefinitionsAsync();

and at that point, the compiler will tell you to make GetBuildState asynchronous and change its return type to Task<IHttpActionResult> .