Node js 、 mongo DB 使用异步从多个集合中获取数据

Question

您好，我正在尝试从数据库获取我所有的博客并更改作者 来自数据库中另一个集合的名称，然后将它们渲染到 ejs 文件，但是页面在数组填满之前呈现

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

请使用博客中作者的引用。换句话说，建立博客与作者的关系。然后您的后端应如下​​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 
 }
});

现在使用此代码，您的整个作者对象将嵌入到每个博客中，如下所示：

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

您可以通过访问 blog.author.name 轻松获取作者详细信息。

Answer 2

对于您的查询，您可以在集合中的 Mongo Schema 中探索 populate。

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)
        }
    )