c#异步调用只能通过一步一步的调试来实现

所以我目前正在用。net构建一个Web Api，并使用实体框架的异步调用。

在控制器的PUT端点上，我试图获取用户是否已经属于另一个级别，或者如果他在DB中，这里是控制器代码:

    [HttpPut]
    public async Task<IHttpActionResult> PutCommittee(CommitteeViewModel committee)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }
        if (!User.IsInRole("Dean") && !User.IsInRole("Chair"))
            return Unauthorized();

        var user = await db.Users.Where(u => u.Cn == User.Identity.Name).FirstOrDefaultAsync();
        if (user == null) { return BadRequest("Your user does not exist"); }
        if (User.IsInRole("Dean"))
        {
            var college = await db.Colleges.Where(c => c.Dean.Cn == user.Cn).FirstOrDefaultAsync();
            if (college == null) { return BadRequest("You're not a Dean of any college"); }
            committee.Name = _utils.getCollegeCommitteeName(college);
        }
        else
        {
            var department = await db.Departments.Where(d => d.Chair.Cn == user.Cn).FirstOrDefaultAsync();
            if (department == null) { return BadRequest("You're not a Chair of any college"); }
            committee.Name = _utils.getDepartmentCommitteeName(department);
        }
        var model = await db.Commitees.Where(c => c.Name == committee.Name).FirstOrDefaultAsync();
        if (model == null)
            return BadRequest("You have no committee");
        var tuple = await getUsers(committee);
        model.Users = tuple.Item1;
        if (model.Users == null)
            return BadRequest(tuple.Item2);
        db.Entry(model).State = EntityState.Modified;
        try
        {
            await db.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            throw;
        }
        return StatusCode(HttpStatusCode.NoContent);
    }

下面是检查用户的函数:

        private async Task<Tuple<List<User>, string>> getUsers(CommitteeViewModel committee)
    {
        string error = "";
        List<User> users = new List<User>();
        var tuple = new Tuple<List<User>, string>(users, error);
        var role = await db.Roles.Where(r => r.Name == "Committee").FirstOrDefaultAsync();
        foreach (UserViewModel u in committee.Users)
        {
            var user = await db.Users.Where(us => us.Cn == u.Cn).FirstOrDefaultAsync();

            if (user != null)
            {
                if (user.Role.Name == "Chair" || user.Role.Name == "Dean")
                {
                    error = "User " +  user.Name + " is a " + user.Role.Name + " and cannot be member of a review committee";
                    return tuple;
                }
                users.Add(user);
            }
            else
            {
                user = _loginProvider.generateUser(u.Cn, role);
                db.Users.Add(user);
                await db.SaveChangesAsync();
                users.Add(user);
            }
        }

        return tuple;
    }

我使用元组，因为async方法不支持OUT参数，以防出现错误。

所以问题是，当我删除用户在我的前端(然后发送一个放置请求与更新的数组)，我一步一步调试，它确实删除它，但当我不，如果我把一个断点在try块，变量模型。Users包含之前的数组(模型中的原始数组)，这只在我从数组中删除用户时发生，奇怪的是，当我同步编写

代码时也发生了这种情况。

谢谢你的帮助。