如何检查用户在数组中已经有 4 张图像，并且不让继续在 Node.js Express 中进行下一步？

Question

我正在尝试设置图像计数的限制。关键是我已经在 Mongoose 中设置了它，但就图像上传到云而言，我认为应该在上传之前添加一些东西，并首先检查图像数组的长度是否小于 4。这是代码。

獴

const userSchema = new mongoose.Schema({
  username: { type: String },
  email: { type: String },
  isVerified: { type: Boolean, default: false },
  picVersion: { type: String, default: '1531305955' },
  picId: { type: String, default: 'default.png' },
  images: {
    type:[{
      imgId: { type: String, default: '' },
      imgVersion: { type: String, default: '' }
    }],
    validate: [arrayLimit, 'You can upload only 4 images']
  },
  city: { type: String, default: '' },
});

function arrayLimit(val) {
  return val.length <= 4;
}

控制器

 UploadImage(req, res) {
 // check if images array length is <== 4 and then let bellow function
    cloudinary.uploader.upload(req.body.image, async result => {
      await User.update(
        {
          _id: req.user._id
        },
        {
          $push: {
            images: {
              imgId: result.public_id,
              imgVersion: result.version
            }
          }
        }
      )
        .then(() =>
          res
            .status(HttpStatus.OK)
            .json({ message: 'Image uploaded successfully' })
        )
        .catch(err =>
          res
            .status(HttpStatus.INTERNAL_SERVER_ERROR)
            .json({ message: 'Error uploading image' })
        );
    });
  },

我应该在cloudinary.uploader.upload(req.body.image, async result => {之前添加什么先检查一下？

Answer 1

好吧，

你实际上可以改变你做更新伙伴的方式。我建议您使用 findOne（） 然后使用更新您的用户，因为这样做时，您可以更好地控制更新，而不仅仅是使用 update。所以在这里尝试这样

UploadImage(req, res) {
User.findOne({ _id: req.user._id })
.then((user) => {
    if (user) {
        if (user.images.type.length <= 4) {
            cloudinary.uploader.upload(req.body.image, async result => {
                user.image.type.push({ imgId: result.public_id, imgVersion: result.version });
                user.save()
                    .then(res.status(HttpStatus.OK).json({ message: 'Image uploaded successfully' }))
                    .catch(); //use callback inside save() or use it like promise
            });
        }
    } else { res.status(HttpStatus.INTERNAL_SERVER_ERROR).json({ message: 'Error uploading image' }); }
})
.catch(err => res.status(HttpStatus.INTERNAL_SERVER_ERROR).json({ message: 'Error uploading image' }));

}

通过这样做，您可以实现您正在寻找的东西..干杯:)