是否可以将await与使用自定义功能的查询一起使用

paul deter 发表于 Dev

保罗·德斯特

我想等待此查询再继续执行其他操作。我已经看到了与此主题相关的几个问题，但是这些问题都没有在查询中使用自定义函数，这使其变得有些棘手。甚至可以将await与以下查询一起使用。我正在使用Microsoft Async包在.NET4.0中使用await-async。（https://www.nuget.org/packages/Microsoft.Bcl.Async/）

var Employees = 
    (from d in context.Employees
    join a in context.Address on d.ID equals a.EmployeeID
    select new 
    {
        Employee = d,
        Address = a,
    })
    .AsEnumerable() memory
    .Select(x => new Employee
    {
        Id = x.Employee.Id,
        PreferredName = GetPreferredName(x.Employee.FirstName, x.Employee.MiddleName, x.Employee.LastName, x.Employee.Alias),
        StreetAddress = x.Address.StreetAddress 
    })
    .ToList();

private string GetPreferredName(string firstName, string middleName, string lastName, string dnsName)
        {
            if (!string.IsNullOrEmpty(firstName))
            return firstName;
            else if (!string.IsNullOrEmpty(middleName))
                return middleName;
            else if (!string.IsNullOrEmpty(lastName))
                return lastName;
            else if (!string.IsNullOrEmpty(dnsName))
                return dnsName;

            return "";
        }

务实的

您可以ToListAsync用来异步获取EF查询的结果。

var query = await
    (from d in context.Employees
    join a in context.Address on d.ID equals a.EmployeeID
    select new 
    {
        Employee = d,
        Address = a,
    })
    .ToListAsync();

var Employees = query    
    .Select(x => new Employee
    {
        Id = x.Employee.Id,
        PreferredName = GetPreferredName(x.Employee.FirstName, x.Employee.MiddleName, x.Employee.LastName, x.Employee.Alias),
        StreetAddress = x.Address.StreetAddress 
    })
    .ToList();