c# - WebAPI 异步方法错误

Question

正如您在下面的代码中看到的，当我尝试从数据层异步调用该方法时，出现以下两个错误。

如何异步调用该方法而不出现这些错误？

• System.Runtime.CompilerServices.IAsyncStateMachine' is not defined or

• imported Cannot find all types required by the 'async' modifier. Are you targeting the wrong framework version, or missing a reference to an assembly?

APIProject.DAL

public class Account : BaseLayer
{
    public static Result SignIn(string userName, string userPass)
    {
        var inputParameters = new Dictionary<string, object>();
        inputParameters.Add("IN_USERNAME", userName);
        inputParameters.Add("IN_USERPASS", userPass);
        var response = ListStoredProcedure(Procedure.SignIn, inputParameters);
        var resultSet = new List<User>();
        foreach (DataRow row in response.DataTable.Rows)
        {
            resultSet.Add(new User
            {
                UserId   = row.GetVarchar("USERID"),
                Fullname = row.GetVarchar("FULLNAME")
            });
        }
        return new Result
        {
            HasResult = response.HasResult,
            Message   = response.Message,
            ResultSet = resultSet
        };
    }
}

APIProject.WebAPI

using System.Threading.Tasks;
public class AccountController : ApiController
{
    public async Task<Result> SignIn(LogInModel model)
    {
        Result r = APIProject.DAL.Account.SignIn(model.UserName, model.UserPass);
        return await Task.Factory.StartNew<Result>(() => r);
    }
}

Answer 1

您需要将项目更新到 .NET 4.5 或更高版本，和 set httpRuntime.targetFramework in your web.config to the appropriate value .

如果跳过第二步，async/await 将编译，但可能无法正常工作。