如何在Meteor服务器端做mongo组

Question

在meteor mongoshell上我可以使用db.collection.group,但是从Meteor.methods我可以,因为Meteor不支持它.

我怎么能写一个类似于以下方法的方法:

db.orders.group({
  keyf: function(doc) {return {year:doc.createdAt.toISOString().substring(0, 4)}},
  initial: {months:{}},
  reduce: function(order, result) {
    var month = order.createdAt.getMonth()+1,
        date = order.createdAt.getDate();

    month = result.months[month] || (result.months[month] = {});
    date = month[date] || (month[date] = []);
    date.push(order);
  },
  cond: {$and: [{createdAt: {$gt: new Date("2015-01-01")}, createdAt: {$lt: new Date("2015-12-31")}}]}
})

期望结果是按月分组的对象组,然后按月内的日期分组.

PS orders,是一个非常大的集合,我真的想在数据库中进行分组.

---

在1.0.4中关于rawCollection()的信息后,我尝试了这个:

  collection = Orders.rawCollection();
  params = {
    keyf: function(doc) {return {year:doc.createdAt.toISOString().substring(0, 4)}},
    initial: {months:{}},
    reduce: function(order, result) {
      var month = order.createdAt.getMonth()+1,
          date = order.createdAt.getDate();

      month = result.months[month] || (result.months[month] = {});
      date = month[date] || (month[date] = []);
      date.push(order);
    },
    cond: {$and: [{createdAt: {$gt: new Date("2015-01-01")}, createdAt: {$lt: new Date("2015-12-31")}}]}
  };
  Meteor.wrapAsync(collection.group, collection)(params);

我越来越:

W20150327-13:26:24.924(2)? (STDERR) /Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/connection/base.js:246
W20150327-13:26:24.924(2)? (STDERR)         throw message;      
W20150327-13:26:24.924(2)? (STDERR)               ^
W20150327-13:26:24.929(2)? (STDERR) TypeError: undefined is not a function
W20150327-13:26:24.929(2)? (STDERR)     at /Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/collection/aggregation.js:229:22
W20150327-13:26:24.931(2)? (STDERR)     at /Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1191:22
W20150327-13:26:24.931(2)? (STDERR)     at /Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1903:9
W20150327-13:26:24.931(2)? (STDERR)     at [object Object].Base._callHandler (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/connection/base.js:453:41)
W20150327-13:26:24.932(2)? (STDERR)     at /Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1758:29
W20150327-13:26:24.932(2)? (STDERR)     at [object Object].Connection.write (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/connection/connection.js:272:16)
W20150327-13:26:24.932(2)? (STDERR)     at __executeQueryCommand (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1752:16)
W20150327-13:26:24.932(2)? (STDERR)     at Db._executeQueryCommand (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1902:7)
W20150327-13:26:24.933(2)? (STDERR)     at Db.command (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/db.js:1183:8)
W20150327-13:26:24.933(2)? (STDERR)     at Collection.group (/Users/jaro/.meteor/packages/mongo/.1.1.0.1jqg8g6++os+web.browser+web.cordova/npm/node_modules/mongodb/lib/mongodb/collection/aggregation.js:228:13)
=> Exited with code: 8

Answer 1

截至Meteor v1.0.4:

通过new rawCollection和rawDatabasemethods on提供对npm Mongo驱动程序中的集合和数据库对象的直接访问Mongo.Collection

因此,您可以调用collection.rawCollection()以获取基础集合对象:

var rawCollection = Orders.rawCollection();

这rawCollection有一个方法group,它等同group于MongoDB shell中的方法.但是,底层节点API是异步的,因此您需要以某种方式将其转换为同步函数.我们不能Meteor.wrapAsync直接使用因为group获取不是主要回调的函数参数,所以我们将使用包装器来解决这个问题:

function ordersGroup(/* arguments */) {
    var args = _.toArray(arguments);
    return Meteor.wrapAsync(function (callback) {
        rawCollection.group.apply(rawCollection, args.concat([callback]));
    })();
}

在你的方法中,你可以ordersGroup像db.orders.group在Mongo shell中一样调用.但是,参数是分开传递的,而不是在对象中传递:

ordersGroup(keys, condition, initial, reduce[, finalize[, command[, options]]])

有关更多信息,请参阅此文档(尽管请注意,callback应该省略该参数,因为我们的异步包装会处理这个问题).

所以你必须单独传递它们:

var result = ordersGroup(
    // keys
    function(doc) {
        return { year: doc.createdAt.toISOString().substring(0, 4) };
    },

    // condition
    {createdAt: {$lt: new Date("2015-12-31"), $gt: new Date("2015-01-01")}},

    // initial
    {months: {}},

    // reduce
    function(order, result) {
        var month = order.createdAt.getMonth()+1,
            date = order.createdAt.getDate();

        month = result.months[month] || (result.months[month] = {});
        date = month[date] || (month[date] = []);
        date.push(order);
    }
);

当然,这仅适用于服务器,因此请确保您的方法仅在服务器代码中(最好在server子目录中,或在内部if (Meteor.isServer)).