javascript - MongoDb、NodeJs、Express 和 Angular 2，来自两个集合的数据连接、检索和显示

Question

我有两个 mongo 集合:

• 位置:(locationId、locationCity、locationState、locationZip 等)
• carLocations:{carId、carType、carMake、locationId}

我要检索数据

carAvailability: {locationCity, locationState, locationZip, carMake, carType}

在我的 nodejs 层中，这是我想要做的:

首先，我尝试通过 locationCity、locationState 或 locationZip 检索 locationId 数组。获得 locationId 数组后，我将尝试检索 carLocations。

app.get("/api/carsbylocationids", function (req, res) {
  //console.log(" locationid:" + req.query.locationid);
  var locationIds  = JSON.parse(req.query.locationIds);
  console.log("locationIds: " + locationIds);
  console.log("carId: " + req.query.carId);
  db.collection(carsLocations).find(
    {
      'locationId': {$in:locationIds},
      'carId': req.query.carId
    }
  ).toArray(function (err, docs) {
    if (err) {
      handleError(res, err.message, "Failed to get items.");
    } else {
      res.header('Access-Control-Allow-Origin', '*');
      res.header('Access-Control-Allow-Methods', 'GET);
      res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');
      res.status(200).json(docs);
    }
  });

});

在这部分或 angularJS 2 代码(此处未提供)中，我想要 carAvailability: {locationCity, locationState, locationZip, carMake, carType} 以便我可以遍历并显示在屏幕上。

我无法找到最佳/有效的方法。我应该在 nodeJS 层还是 Angular2 层处理这种连接类型的条件？

Answer 1

我使用 $lookup 和 $match 的聚合从 mongoDb 获取数据。对于那些想要细节的人:

app.get("/api/locationsByitemid", function (req, res) {
  console.log(" itemid:" + req.query.itemid + " city:" + req.query.locationCity + " state:" + req.query.locationState);

  db.collection(LOCATIONS_COLLECTION).aggregate([
    { $lookup: { from: ITEMS_COLLECTION, localField: "locationId",foreignField: "locationId", as: "locationsbyLocationId"} },
    { $unwind:"$locationsbyLocationId"},
    { "$match": { 'locationsbyLocationId.itemid': req.query.itemid, 'locationCity': req.query.locationCity, 'locationState' : req.query.locationState} }
    ]
  ).toArray(function (err, docs) {
    if (err) {
      handleError(res, err.message, "Failed to get items.");
    } else {
      res.header('Access-Control-Allow-Origin', '*');
      res.header('Access-Control-Allow-Methods', 'GET');
      res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');
      res.status(200).json(docs);
    }
  });

});

这是令我满意的工作，但欢迎提出任何建议....感谢那些指出最好在调用 RestFul 服务之前处理此问题的人。这就是我探索的内容。