如何过滤重复和空文档，以及使用JavaScript订购MongoDB集合？

获取MongoDB集合中的所有数据非常简单。您只需使用集合实例名称并调用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();
        }
    });
}

但是我的收藏有一些重复的数据和一些空记录。我如何过滤掉这些？我还想按两个字段排序。我的收藏结构和写作目的如下：

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），它们将按以下顺序返回：

Helena      Montana     1984    1984
San Andreas California  1984    1987

（反之亦然）

那么，我如何过滤掉空的和冗余的文档，并按指定的字段对文档进行排序呢

更新 考虑到答案不返回任何数据的问题可能是“city”字段应该是“Tsu city”，而“state”字段应该是“Tsu state”，我尝试了以下方法：

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

…但它仍然不返回任何数据

更新2 当我在控制台中输入此命令时：

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

我得到：

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)

模板帮助程序中的异常：错误：不一致的运算符：{“$exists”：true，“ne”：“”} 在http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1269:15 at功能。每个功能。每个功能(http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22) 在等位面对象上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1263:5) 在compileValueSelector上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1459:14) 在http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1439:9 at功能。每个功能。每个功能(http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22) 在CompiledDocumentSelector上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1422:5) 在u.extend.\u编译器选择器(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1399:12) 在新的Minimongo Matcher(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1342:27) 在新的LocalCollection.Cursor(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:144:20) XHR已完成加载：获取“http://localhost:3000/sockjs/info?cb=8zcc5akr4u". 返回TimeAndSpace.find( {sort:{tsu yearin:1，tsu yearout:1}} ); 未捕获的SyntaxError:非法返回语句 在Object.InjectedScript.\u evaluateOn（：905:140） 在Object.InjectedScript.\u evaluateAndWrap（：838:34） 在Object.InjectedScript.evaluate（：694:21） 找到时间和空间( {ts_市：{$exists:true，ne:'}，ts_州：{$exists:true，ne:'}， {sort:{tsu yearin:1，tsu yearout:1}} ); 未捕获错误：运算符不一致：{“$exists”：true，“ne”：“”} 在http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1269:15 at功能。每个功能。每个功能(http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22) 在等位面对象上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1263:5) 在compileValueSelector上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1459:14) 在http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1439:9 at功能。每个功能。每个功能(http://localhost:3000/packages/underscore.js?0a80a8623e1b40b5df5a05582f288ddd586eaa18:164:22) 在CompiledDocumentSelector上(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1422:5) 在u.extend.\u编译器选择器(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1399:12) 在新的Minimongo Matcher(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:1342:27) 在新的LocalCollection.Cursor(http://localhost:3000/packages/minimongo.js?af9eb9d7447544ca9b839a3dcf7ed2da2209b56c:144:20)

---

让我们先看简单的，消除空白和排序：

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

---

另一方面，重复数据消除可能最好由cron作业来处理，该作业会查找您所关心的重复类型并删除有问题的文档。在查询过程中，这实际上是不可能的，在呈现过程中，这将是一个PIA。

我在排序行中添加了第二个“}”，以使其“编译”（并在上面添加了这一点），但现在它什么也不返回…抱歉，忘记了城市和州键上的前缀。我在控制台中添加了err msgs来更新2。是的，在“ne”前面加“$”就可以了-谢谢！