无法使用多个 find() 函数使用 mongoose 传入 res.render

问题描述

我正在开发一个网站，该网站在主页上显示不同类别组中的几部电影，因此我尝试使用多个查找功能（猫鼬）并将它们传递到渲染中以将它们一起显示在视图中。问题是，如果我尝试将 find 函数中的电影数组存储在变量或 res.locals 中，它只是保持“未定义”。我似乎无法弄清楚如何在一个 get 响应中传递这些数组中的几个。我是 Node 的新手，感谢您的帮助！

app.get("/",(req,res) => {
  // array of top-selling movies
  Movie.find({
    group: "Top-Selling Movies"
  },function(err,movies) {
    if (err) {
      console.log(err);
    } else {
      // In EJS,use found items array and tap into attributes to display in frontend
      res.locals.topMovies = movies;
    }
  });
  // array of new movies
  Movie.find({
    group: "New rental movies"
  },use found items array and tap into attributes to display in frontend
      res.locals.newMovies = movies;
    }
  });
  // array of recommended movies
  Movie.find({
    group: "Recommended For You"
  },use found items array and tap into attributes to display in frontend
      res.locals.recMovies = movies;
    }
  });
  // array of action/thrilling movies
  Movie.find({
    group: "Thrilling movies"
  },use found items array and tap into attributes to display in frontend
      res.locals.actionMovies = movies;
    }
  });
  res.render("categories");
});

我什至尝试过：

app.get("/",res) => {
  var topMovies;
  var newMovies;
  var recMovies;
  var actionMovies;
  // array of top-selling movies
  Movie.find({
    group: "Top-Selling Movies"
  },use found items array and tap into attributes to display in frontend
      topMovies = movies;
    }
  });
  // array of new movies
  Movie.find({
    group: "New rental movies"
  },use found items array and tap into attributes to display in frontend
      newMovies = movies;
    }
  });
  // array of recommended movies
  Movie.find({
    group: "Recommended For You"
  },use found items array and tap into attributes to display in frontend
      recMovies = movies;
    }
  });
  // array of action/thrilling movies
  Movie.find({
    group: "Thrilling movies"
  },use found items array and tap into attributes to display in frontend
      actionMovies = movies;
    }
  });
  res.render("categories",{
    topMovies: topMovies,newMovies: newMovies,recMovies: recMovies,actionMovies: actionMovies
  });

解决方法

您可以为此使用 async/await

app.get("/",async (req,res) => {
  const topMovies = await Movie.find({ group: "Top-Selling Movies" })
  const newMovies = await Movie.find({ group: "New rental movies" })
  const recMovies = await Movie.find({ group: "Recommended For You" })
  const actionMovies = await Movie.find({ group: "Thrilling movies" })


  return res.render("categories",{
    topMovies: topMovies,newMovies: newMovies,recMovies: recMovies,actionMovies: actionMovies
  });
});

或者为了更好看的代码

app.get("/",res) => {
  const [topMovies,newMovies,recMovies,actionMovies] = await Promise.all([
    Movie.find({ group: "Top-Selling Movies" }),Movie.find({ group: "New rental movies" }),Movie.find({ group: "Recommended For You" }),Movie.find({ group: "Thrilling movies" })
  ])


  return res.render("categories",{
    topMovies,actionMovies
  });
});

编辑：同样在您的示例中，您可以仅使用过滤器方法来限制数据库查询

app.get("/",res) => {
  const movies = await Movie.find()

  const topMovies = movies.filter(movie => movie.group === 'Top-Selling Movies');
  const newMovies = movies.filter(movie => movie.group === 'New rental movies');
  const recMovies = movies.filter(movie => movie.group === 'Recommended For You');
  const actionMovies = movies.filter(movie => movie.group === 'Thrilling movies');

  return res.render("categories",actionMovies
  });
});