猫鼬（mongo），复制一份文件

Question

尝试复制文档。首先，我找到它。然后删除_id。然后插入它。但是calculate._id仍然存在。所以我得到了一个重复错误。我究竟做错了什么？

mongoose.model('calculations').findOne({calcId:req.params.calcId}, function(){
      if(err) handleErr(err, res, 'Something went wrong when trying to find calculation by id');

      delete calculation._id;
      console.log(calculation); //The _.id is still there
      mongoose.model('calculations').create(calculation, function(err, stat){
        if(err) handleErr(err, res, 'Something went wrong when trying to copy a calculation');
        res.send(200);
      })
    });

Answer 1

从findOne返回的对象不是普通对象而是Mongoose文档。您应该使用{lean:true}选项或.toObject()方法将其转换为纯JavaScript对象。

mongoose.model('calculations').findOne({calcId:req.params.calcId}, function(err,calculation){
  if(err) handleErr(err, res, 'Something went wrong when trying to find calculation by id');

  var plainCalculation = calculation.toObject();


  delete plainCalculation._id;
  console.log(plainCalculation); //no _id here
});