这是定义模式的一种方法：

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
  email: {type: String, index: true},
  country: {type: String, index: true},
  signup_date: { type : Date, default: Date.now, index: true },
});

mongoose.model('User', UserSchema);

然后搜索：

var User = require('mongoose').model('User');

const mySearch = async () => {
  const time = new Date("March 1 2023").toISOString(); 
  // properly format timestamp for mongodb query
  // "March 1 2023" is an example (or use something like req.body.myTimeVar)

  var myUser = await User.find({country: req.body.country,
    signup_date: {
      $gte: time // $gte: greater than or equal to (also see $lte, $gt, $lt, etc)
    }
  });
}