Node.js，mongo DB使用異步從多個collections獲取數據

Question

你好，我正在嘗試從數據庫中獲取我所有的博客，並從數據庫中的另一個集合中更改作者姓名，然后將它們呈現為 ejs 文件，但是頁面在數組填滿之前呈現

app.get('/', async (req, res) => {
      let blogList = new Array(); 
      await Blog.find({}, function (err, foundBlog) { 
        console.log(foundBlog);
        if (err) {
          console.log(err);
        } else {
          foundBlog.forEach(async (blog) => {
            await Author.findById(blog.author, async (err, author) => {
              if (err) {
                console.log(err);
              } else {
                blog.author = author.name;
                console.log('this is the blogs' + blog);
                blogList.push(blog);
                console.log('array length 1 is ' + blogList.length);
              }
            });
          });
          console.log('array length 2 is ' + blogList.length);
          console.log(blogList);
          res.render('home', { blogs: blogList });
        }
      });
    });

Answer 1

請在博客中使用作者的參考。 換句話說，建立博客與作者的關系。 然后你的后端應該如下所示：

app.get('/', async (req, res) => {
      
         const blogs=await Blog.find({}).populate('author').exec(); // field name author is being populated.
      
          res.render('home', { blogs });
        }
    
    );

const BlogSchema=new mongoose.Schema({
 ... rest of fields,
 author:{
  type:ObjectId,
  ref:"Author" // here it is model name 
 }
});

使用此代碼，您的整個作者 object 將嵌入每個博客中，例如：

blog={
  name:"",
  author:{
    name:"Abc",
  }
}

您可以通過訪問 blog.author.name 輕松獲取作者詳細信息。

Answer 2

對於您的查詢，您可以在集合中探索填充到您的 Mongo 架構中。

const BlogSchema = new mongoose.Schema({
 author:{
  type:ObjectId,
  ref:"Author" //here it is model name 
 }
})
const Blog = mongoose.model("Blog", BlogSchema )

const AutherSchema = new mongoose.Schema({
 _id:{
  type:ObjectId
 }
})
const Auther = mongoose.model("Auther", AutherSchema)

 app.get('/', async (req, res) => {
      
 const blogs = await Blog.find({}).populate('author').exec(); // field name author is being populated.
         res.send(blogs)
        }
    )