当我尝试从IHttpContextAccessor字段获取httpcontext时,我遇到了问题。
有我的startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddDistributedMemoryCache();
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddTransient<IUserContextServices, UserContextService>();
services.AddSession(options =>
{
options.Cookie.Name = ".AdventureWorks.Session";
options.IdleTimeout = TimeSpan.FromSeconds(10);
});
}
这是实现IUserContext接口的My UserContext类
public class UserContextService : IUserContextServices
{
private readonly IHttpContextAccessor contextAccessor;
PQADBContext _context = new PQADBContext();
public UserContextService(IHttpContextAccessor accessor)
{
contextAccessor = accessor;
}
public UserContextService()
{
}
public HttpContext Context
{
get
{
return contextAccessor.HttpContext;
}
}
public int UserID()
{
return Context.Session.GetID("UserID").ConvertToInt();
}
public bool isLogin()
{
return Context.Session.GetBoolean("isLogin").ConvertToBool();
}
public UserAccount CreateSession(LoginViewModel logindata, bool EncryptPwd = true)
{
string error;
error = "";
try
{
string EncPwd = EncryptPwd ? EncryptDecryptHelper.Encrypt(logindata.Password) : logindata.Password;
var UserDetail =_context.UserAccount.Where(e => e.P_No == logindata.PNo && e.Password == EncPwd).SingleOrDefault();
if (UserDetail != null)
{
//HttpContext.Session.SetInt32()
// ///put all the properties in session variables
Context.Session.SetBoolean("isLogin", true);
Context.Session.SetID("UserID",UserDetail.AccountId);
Context.Session.SetID("P_No",Convert.ToInt32(UserDetail.P_No));
Context.Session.SetBoolean("isActive", true);
Context.Session.SetBoolean("Email", true);
Context.Session.SetID("RoleId", 1);
Context.Session.SetString("userName", "admin");
}
上面的类中提供了httpContext,并且还设置了Session值,但是当我尝试访问此类中的httpcontext时,它为我提供了空对象引用
public class UserService
{
private readonly IHttpContextAccessor contextAccessor;
public IUserContextServices _userContext = new UserContextService();
public UserService()
{
}
public bool CreateEmployee(AppEmployees appemployee, int RoleId, bool isEmailSend, out string error)
{
appemployee.CreatedBy = _userContext.UserID(); //this line shows null reference exception
appemployee.CreatedDate = DateTime.Now;
}
最佳答案
为什么在UserService中使用默认构造函数?
您使用下一个代码:
public IUserContextServices _userContext = new UserContextService();
当然,这里
IHttpContextAccessor
为空。您需要在UserService中使用DI。
例:
private readonly IUserContextService _userContextService;
public UserService(IUserContextService userContextService)
{
_userContextService = userContextService;
}
.NET Core中有关DI的很好的post。
关于c# - IHttpContextAccessor在类中为null,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/49032091/