mongo聚合查询在golang与mgo驱动程序 [英] mongo aggregation query in golang with mgo driver

问题描述

我在mongodb中有以下查询 -

I have the following query in mongodb -

db.devices.aggregate({
$match: {userId: "v73TuQqZykbxFXsWo", state: true}},
{
  $project: {
    userId: 1,
    categorySlug: 1,
    weight: { 
      $cond: [ 
        {"$or": [  
          {$eq: ["$categorySlug", "air_fryer"] }, 
          {$eq: ["$categorySlug", "iron"] } 
        ] }, 
      0, 1] } 
    } },  
    {$sort: {weight: 1}},
    { $limit : 10 }
);

我正尝试使用mgo驱动程序在golang中编写此代码，但无法绕过我的头这是所有！

I'm trying to write this in golang using the mgo driver but not able to wrap my head around this at all!

如何将此转换为golang mgo查询？

How do I translate this to a golang mgo query?

推荐答案

文档上的例子足以开始使用。但是，如果您对golang不熟悉， $ cond 部分可能会有点棘手。请参阅下面的示例代码：

The examples on the docs would be sufficient to get started. However, if you are not familiar with golang, the $cond part could be a bit tricky. See below example code:

    collection := session.DB("dbName").C("devices")

    stage_match := bson.M{"$match":bson.M{"userId":"v73TuQqZykbxFXsWo", "state": true}}

    condition_weight := []interface{}{bson.M{"$or": []bson.M{
                       bson.M{"$eq": []string{"$categorySlug", "air_fryer"}},
                       bson.M{"$eq": []string{"$categorySlug", "iron"}},
    }}, 0, 1}

    stage_project:= bson.M{"$project": bson.M{"userId":1, "categorySlug":1, "weight": condition_weight}}

    stage_sort := bson.M{"$sort": bson.M{"weight":1}}

    stage_limit := bson.M{"$limit": 10}

    pipe := collection.Pipe([]bson.M{stage_match, stage_project, stage_sort, stage_limit})

另请参阅 mgo：type Pipe

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