Mongo 3.6的汇总问题 [英] Aggregation issue with Mongo 3.6

问题描述

我正在使用聚合函数，连接3.4 mongodb时没有任何问题.

I was using the aggregate function without any problem connecting a 3.4 mongodb.

当我更改为3.6 db时，

When I change to a 3.6 db,

我已收到消息:除"explain"参数的聚合值外，"cursor"选项是必需的.

对不起，如果它已经发布.我找不到任何解决办法

Sorry if it's already posted. I am unable to find any solutions

推荐答案

在mongo 3.6中，使用聚合时发生了一些变化，必须使用游标，除非您包含了explain选项，否则必须指定游标选项.我遇到了和您一样的错误.现在，您必须像这样

In mongo 3.6 there has been changes while using aggregate you have to use cursor, unless you include the explain option, you must specify the cursor option. I faced same error as you were facing. Now you have to do it like

this.aggregate( [
        { $unwind : "$tags" },
        {$group: {_id: '$tags', count: { $sum: 1} }},
        {$sort: { count: 1 }}
            ] ).cursor({}).exec();

现在，您可以使用游标方法cursor.toArray()返回包含游标中所有文档的数组.从聚合返回的游标仅支持对评估的游标(例如cursor.toArray())进行操作的游标方法，要了解更多游标方法，可以单击

Now you can use cursor method cursor.toArray() to return an array that contains all the documents from a cursor. Cursors returned from aggregation only supports cursor methods that operate on evaluated cursors like cursor.toArray(), to know about more cursor methods you can click here and get further.

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