前段时间接触freemaker时,本来后端写各接口运行正常,但加入了模板后,频繁报空指针问题,整了许久,最后还是请教了别人解决了这个问题,现在记录下来,方便以后碰到了可以查阅. 错误样例如下: ERROR: freemarker.runtime - Error executing FreeMarker template FreeMarker template error: The following has evaluated to null or missing: ==> user [in t
用如下方法获取UserId报空引用异常 public class BaseController : Controller { protected SiteContext db = new SiteContext(); protected Guid userId; public BaseController() { userId = Guid.Parse(User.Identity.GetUserId()); } } 由于Controller未初始化完成,User为空,重写初始化方法,在初始化
#include <iostream> #include <cstdlib> #include <ctime> #include <fstream> using namespace std; const int n = 40; const int m = 66; const int lenth = 2640; #define random(a,b) (rand() % (b-a+1))+ a /* run this program using the con