如何过滤掉重复和空文档以及使用 JavaScript 订购 MongoDB 集合？

Question

获取 MongoDB 集合中的所有数据非常简单。您只需使用 Collection 实例名称并调用 find：

TimeAndSpace = new Mongo.Collection('timeAndSpace');

if (Meteor.isClient) {
    . . .
    Template.placesLived.helpers({
        places: function () {
            // this helper returns a cursor of all of the documents in the collection
            return TimeAndSpace.find();
        }
    });
}

但我的收藏有一些重复数据和一些空记录。我如何过滤掉这些？我也想按两个字段排序。我的收藏的结构和写入如下：

TimeAndSpace = new Mongo.Collection('timeAndSpace');

if (Meteor.isClient) {
    Template.addTimeSpaceForm.events({
        'submit form': function(event){
            event.preventDefault();
            var city = event.target.city.value;
            var state = event.target.state.value;
            var yearin = event.target.yearin.value;
            var yearout = event.target.yearout.value;

            Meteor.call('insertLocationData', city, state, yearin, yearout);
        }
    });
}

if (Meteor.isServer) {
  Meteor.startup(function () {
    // code to run on server at startup
  });

  Meteor.methods({
      'insertLocationData': function(city, state, yearin, yearout){
          TimeAndSpace.insert({
              ts_city: city,
              ts_state: state,
              ts_yearin: yearin,
              ts_yearout: yearout
          });
      }
  });
}

我希望文档首先按 yearin 排序，然后按 yearout 排序（这样如果有多个文档具有相同的 yearin 值（例如 1984），它们将按此顺序返回：

Helena      Montana     1984    1984
San Andreas California  1984    1987

（反之亦然）

那么如何过滤掉空的和多余的文档，并按指定字段排序文档呢？

更新

认为答案没有返回任何数据的问题可能是“城市”字段应该是“ts_city”而“州”字段应该是“ts_state”，我尝试了这个：

return TimeAndSpace.find(
  {ts_city: {$exists: true, ne: ""}, ts_state: {$exists: true, ne: ""}},
  {sort: {ts_yearin: 1, ts_yearout: 1}}
);

...但它仍然没有返回任何数据。

更新 2

当我在控制台中输入这个时：

TimeAndSpace.find(
  {ts_city: {$exists: true, ne: ""}, ts_state: {$exists: true, ne: ""}},
  {sort: {ts_yearin: 1, ts_yearout: 1}}
);

我明白了：

Exception in template helper: Error: Inconsistent operator: {"$exists":true,"ne":""}
    at http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1269:15
    at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22)
    at isOperatorObject (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1263:5)
    at compileValueSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1459:14)
    at http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1439:9
    at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22)
    at compileDocumentSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1422:5)
    at _.extend._compileSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1399:12)
    at new Minimongo.Matcher (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1342:27)
    at new LocalCollection.Cursor (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:144:20)
XHR finished loading: GET "http://localhost:3000/sockjs/info?cb=8zcc5akr4u".
return TimeAndSpace.find(
  {sort: {ts_yearin: 1, ts_yearout: 1}}
);
Uncaught SyntaxError: Illegal return statement
    at Object.InjectedScript._evaluateOn (<anonymous>:905:140)
    at Object.InjectedScript._evaluateAndWrap (<anonymous>:838:34)
    at Object.InjectedScript.evaluate (<anonymous>:694:21)
TimeAndSpace.find(
  {ts_city: {$exists: true, ne: ""}, ts_state: {$exists: true, ne: ""}},
  {sort: {ts_yearin: 1, ts_yearout: 1}}
);
Uncaught Error: Inconsistent operator: {"$exists":true,"ne":""}
    at http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1269:15
    at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22)
    at isOperatorObject (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1263:5)
    at compileValueSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1459:14)
    at http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1439:9
    at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22)
    at compileDocumentSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1422:5)
    at _.extend._compileSelector (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1399:12)
    at new Minimongo.Matcher (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1342:27)
    at new LocalCollection.Cursor (http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:144:20)

Answer 1

让我们先看简单的，消除空格和排序：

return TimeAndSpace.find(
  {ts_city: {$exists: true, $ne: ""}, ts_state: {$exists: true, $ne: ""}},
  {sort: {ts_yearin: 1, ts_yearout: 1}}
);

另一方面，重复数据删除可能最好由 cron 作业来处理，该作业查找您关注的重复数据类型并删除有问题的文档。在查询期间这实际上是不可能的，在渲染期间它会是一个 PIA。