在路径"_id"中，值XXX的猫鼬错误转换为ObjectId失败了吗?

问题描述

向/customers/41224d776a326fb40f000001发送请求并且不存在带有_id 41224d776a326fb40f000001的文档时，doc是null，而我返回的是404:

When sending a request to /customers/41224d776a326fb40f000001 and a document with _id 41224d776a326fb40f000001 does not exist, doc is null and I'm returning a 404:

  Controller.prototype.show = function(id, res) {
    this.model.findById(id, function(err, doc) {
      if (err) {
        throw err;
      }
      if (!doc) {
        res.send(404);
      }
      return res.send(doc);
    });
  };

但是，当_id与Mongoose期望的格式"(我想)不符时(例如，对于GET /customers/foo)，将返回一个奇怪的错误:

However, when _id does not match what Mongoose expects as "format" (I suppose) for example with GET /customers/foo a strange error is returned:

那这是什么错误?

推荐答案

猫鼬的findById方法将id参数强制转换为模型的_id字段的类型，以便其可以正确查询匹配的文档.这是一个ObjectId，但"foo"不是有效的ObjectId，因此强制转换失败.

Mongoose's findById method casts the id parameter to the type of the model's _id field so that it can properly query for the matching doc. This is an ObjectId but "foo" is not a valid ObjectId so the cast fails.

41224d776a326fb40f000001不会发生这种情况，因为该字符串是有效的ObjectId.

This doesn't happen with 41224d776a326fb40f000001 because that string is a valid ObjectId.

解决此问题的一种方法是在您的findById调用之前添加检查，以查看id是有效的ObjectId还是这样:

One way to resolve this is to add a check prior to your findById call to see if id is a valid ObjectId or not like so:

if (id.match(/^[0-9a-fA-F]{24}$/)) {
  // Yes, it's a valid ObjectId, proceed with `findById` call.
}

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