javascript - Nodejs Mongoose 复杂查询

Question

我只是无法理解这个问题。我试图在 Mongoose 中获得查询结果。我有一个旅程数据库，其中包括停靠路线。我想获得访问目标站的所有旅程(奖励:并使用某个平台)。

这是模式的样子:

var StopSchema = new Schema({
  arrival: String,
  departure: String,
  platform: String,
  station: String,
});

var JourneySchema = new Schema({
  trainNumber: String,
  destination: String,
  route: [StopSchema]
});

示例数据:

{
  trainNumber: '1',
  destination: 'Z',
  route: [
  { arrival: "11:23", departure: "11:25", platform: "3", station: "A"},
  { arrival: "11:33", departure: "11:35", platform: "3", station: "B"},
  { arrival: "11:43", departure: "11:45", platform: "3", station: "Z"}
  ]
},
{
  trainNumber: '2',
  destination: 'Z',
  route: [
  { arrival: "12:23", departure: "12:25", platform: "3", station: "A"},
  { arrival: "12:33", departure: "12:35", platform: "3", station: "B"},
  { arrival: "12:43", departure: "12:45", platform: "3", station: "Z"}
  ]
},
{
  trainNumber: '3',
  destination: 'F',
  route: [
  { arrival: "12:23", departure: "12:25", platform: "3", station: "D"},
  { arrival: "12:33", departure: "12:35", platform: "3", station: "E"},
  { arrival: "12:43", departure: "12:45", platform: "3", station: "Z"}
  ] 
}

请求:获取访问“B”(在平台3)的所有旅程，列出路线并推广目标站数据

期望结果:

[
{
  trainNumber: '1',
  destination: 'Z',
  route:  [
  { arrival: "11:23", departure: "11:25", platform: "3", station: "A"},
  { arrival: "11:33", departure: "11:35", platform: "3", station: "B"},
  { arrival: "11:43", departure: "11:45", platform: "3", station: "Z"}
  ],
  targetStation: {  arrival: "11:33", departure: "11:35", platform: "3", station: "B"}
},
{
  trainNumber: '2',
  destination: 'Z',
  route: [
  { arrival: "12:23", departure: "12:25", platform: "3", station: "A"},
  { arrival: "12:33", departure: "12:35", platform: "3", station: "B"},
  { arrival: "12:43", departure: "12:45", platform: "3", station: "Z"}
  ],
  targetStation: {  arrival: "12:33", departure: "12:35", platform: "3", station: "B"}
}
]

我只是不知道我可以使用什么邪恶的 elemmatch/aggregate/virtual/query 组合。

Answer 1

由于 MongoDB 不支持联接，因此您无法在使用所需架构的单个查询中执行此操作。您将至少需要两个查询:一个用于获取目标站点的 ID，另一个用于获取具有该站点的旅程。类似的东西(假设模型 Stop 和 Journey):

Stop.findOne({station: 'B', platform: '3'}).exec().then(function(stop) {
  if (stop === null) { throw new Error('No stop matches request');
  return Journey.find({route: {_id: stop.id}}).populate('route').exec();
}).then(function(journeys) {
  if (journeys === null || journeys.length === 0) { throw new Error('No journeys include requested stop'); }

  // `journeys` should be an array matching your desired output
  //  you can add the extra property here or in the journeys query if you wish
}).then(null, function (err) {
  // Handle errors
});