有没有办法在更新 MongoDb 之前从数据库获取数据 - Mongoose

Question

我想为我的项目做一个更新方法，但我无法解决这个问题。我的模型有一个现场调用 slug。如果我需要我添加数据以使这个值唯一。但是，我在我的更新功能上使用 findByIdAndUpdate 方法。我想知道有没有办法在更新这个模型之前获取数据？我是否必须向我的数据库发出至少 2 个不同的请求才能获取旧数据，或者我使用的这种方法是否让我有机会比较数据？因为如果标题字段已更改，我需要比较它并生成新的 slug 值。

类别模型

const mongoose = require('mongoose')

const CategorySchema = mongoose.Schema({
    title: {
        type: String,
        required: true,
        trim: true,
        minLength: 3,
        maxLength: 70
    },
    description: {
        type: String,
        requried: true,
        trim: true,
        minLength: 30
    },
    coverImage: {
        type: String,
        trim: true
    },
    slug: {
        type: String,
        unique: true,
        required: true
    }
}, {collection: "categories", timestamps: true})

module.exports = mongoose.model('category', CategorySchema);

更新函数

const update = async (req, res, next) => {
    delete req.body.createdAt;
    delete req.body.updatedAt;

    try {
        const data = req.body;
        data.coverImage = req.file ? req.file.path.replace(/\/g, "/") : undefined;
        data.slug = data.title ? slugCreator(data.title, null): undefined;
        const result = await CategoryModel.findByIdAndUpdate(req.params.categoryId, data, { new: true, runValidators: true });
        if (result) {
            return res.json({
                message: "Category has been updated",
                data: result
            });
        }else{
            throw createError(404, "Category not found.")
        }
    } catch (error) {
        next(createError(error));
    }
};

Answer 1

您可以先获取文档来解决您的问题，然后像下面的示例一样使用保存方法进行更新

const update = async (req, res, next) => {
  delete req.body.createdAt;
  delete req.body.updatedAt;
  try {
    const data = req.body;
    //here you have the current category
    const category = await CategoryModel.findById(req.params.categoryId);
    if (!category) {
      throw createError(404, 'Category not found.');
    }
    //do all you comparation and setting the data to the model...
    category.slug = data.title ? slugCreator(data.title, null) : undefined;
    category.coverImage = req.file
      ? req.file.path.replace(/\/g, '/')
      : undefined;

    await category.save();

    return res.json({
      message: 'Category has been updated',
      data: category,
    });
  } catch (error) {
    next(createError(error));
  }
};

有没有办法在更新 MongoDb 之前从数据库获取数据 - Mongoose

Is there a way to get data from db before update for MongoDb - Mongoose

mongoose

mongodb

node.js

express