调用user.find返回一个您不等待的承诺。因此，当您检查p1和p2是否存在时，它返回一个truthy值，因为这两个值都是Promise对象。

若要修复此问题，请在两个用户前面使用await.如下所示查找

const p1 = await User.find({ p1: req.body.p1 });
const p2 = await User.find({ p2: req.body.p2 });

之后，这两个值都将是数组，因为您正在使用find方法，所以只需检查长度属性，或者更好地使用findOne而不是find方法。

const p1 = await User.findOne({ p1: req.body.p1 });
const p2 = await User.findOne({ p2: req.body.p2 });

1. MongoDB .find returns an array. In your case p1 is an empty array. if(p1) will always return true. You should check for its length.
2. You should use await for your query calls.

   const p1 = await User.find({ p1: req.body.p1 });
   const p2 = await User.find({ p2: req.body.p2 });
   

   我在下面粘贴示例代码-

   passport.use(
     "local.signup",
     new LocalStrtegy(
       {
         usernameField: "email",
         passwordField: "password",
         passReqToCallback: true,
       },
       async function (req, email, password, done) {
         req.checkBody("email", "E-mail is empty").notEmpty();
         req
           .checkBody("password", "Your password is too short!")
           .isLength({ min: 4 });
         var errors = await req.validationErrors();
         if (errors) {
           var messages = [];
           errors.forEach(function (error) {
             messages.push(error.msg);
           });
           return done(null, false, req.flash("error", messages));
         }
         const p1 = await User.find({ p1: req.body.p1 });
         const p2 = await User.find({ p2: req.body.p2 });
   
         User.findOne({ email: email }, function (err, user) {
           if (err) {
             return done(err);
           }
   
           if (user) {
             return done(null, false, {
               message:
                 "This E-Mail alredy in use! If you believe that this is an error, please an admin on. (ERR 002 MCEE)",
             });
           } else if (p1.length) { // Check for Length
             return done(null, false, {
               message:
                 "This username is alredy in use! If you believe that this is an error, please contact an admin. (ERR 002 MCEM)",
             });
           } else if (p2.length) { // Check for Length
             return done(null, false, {
               message:
                 "This Tag is alredy in use! If you believe that this is an error, please contact an admin. (ERR 002 MCED)",
             });
           }
   
           console.log(mc + " " + dcign + " " + user);
           var newUser = new User();
           newUser.email = email;
           newUser.password = newUser.encryptPassword(req.body.password);
           newUser.p1 = req.body.p1;
           newUser.p2 = req.body.p2;
           newUser.Banned = false;
           console.log(req.body);
           newUser.save(function (err, result) {
             if (err) {
               return done(err);
             }
             return done(null, newUser);
           });
         });
       }
     )
   );