我收到ArgumentNullException:值不能为null。参数名称:options我认为这是因为我的默认构造函数我得到null但是如果我注释掉构造函数那么类的新实例需要参数,我不知道该给什么.HELP PLEASE
public class OvertimeRequestBusiness
{
public static OvertimeRequestBusiness Instance { get; } = new OvertimeRequestBusiness();
private readonly DbContextOptions<DatabaseContext> _contextOptions;
//default ctor
public OvertimeRequestBusiness() : base() { }
public OvertimeRequestBusiness(DbContextOptions<DatabaseContext> contextOptions)
{
_contextOptions = contextOptions;
}
public async Task<List<User>> GetAllUsersAsync()
{
using (var ctx = new DatabaseContext(_contextOptions))
{
var query = ctx.Users;
var res = await query.ToListAsync();
return res;
}
}
}
在我的控制器中
[Route("users")]
[HttpGet]
public async Task<List<User>> GetAllUsers()
{
return await OvertimeRequestBusiness.Instance.GetAllUsersAsync();
}
以下是如何创建DbContextOptions
:
var optionsBuilder = new DbContextOptionsBuilder<DatabaseContext>();
optionsBuilder.UseSqlServer("connection_string_here");
然后DbContextOptions<DatabaseContext>
将作为optionsBuilder.Options
。你可以将它传递给OvertimeRequestBusiness.ctor
:
new OvertimeRequestBusiness(optionsBuilder.Options);