Question

在将res.json（）与参数一起使用时，会导致CastError： CastError：模型“ Post”的路径“ _id”的值“ undefined”的强制转换为ObjectId失败

如果我仅使用不带参数的rest.status（），res.sendStatus（）或res.json（），则不会出现问题。

exports.createPost = async (req, res, next) => {
  try {
    errorsIsEmpty(validationResult(req));
    const { communityId } = req.params;
    const { type } = req.query;
    const { title, content } = req.body;
    const user = await User.findById(req.userId)
    const community = await Community.findById(communityId);
    const banned = await community.authorized(req.userId)
    if(banned){
      ////// This line causes the problem //////
     return res.status(403).json({})
    }
    else {
      let post;
      if (type === 'text') {
      post = new Post({
        title,
        content,
        authorId: req.userId,
      });
    } else if (type === 'image') {
      if (!req.file) {
        const error = new Error('No image provided.');
        error.statusCode = 422;
        throw error;
      }
      const imageUrl = req.file.path;
      post = new Post({
        title,
        imageUrl,
        authorId: req.userId,
      });
    }
    await post.save();
  ////// This line works//////
    res.status(201).json({ postId: post._id });
    }
    
  } catch (err) {
    console.log(err);
    next(err);
    // errorFunc(err, next);
  }
};

模型“ Post”的路径“ _id”处的

r值“ undefined”

Answer 1

您的_id是一个字符串，但必须是ObjectId类型。我以为你在用猫鼬。您需要导入/需要猫鼬，然后将_id值包装在ObjectId

中

const mongoose = require('mongoose');

const ObjectId = mongoose.Types.ObjectId;

// in your route handler
  await post.save();
  ////// This line works//////
  res.status(201).json({ postId: ObjectId(post._id) });

res.json（）创建CastError

1 个答案: