Mongo DB聚合多个条件 [英] Mongo db aggregation multiple conditions

问题描述

我想投影一个仅当字段在范围内时才应用导出值的集合.

I want to project a collection applying exporting a value only if a field is inside a range.

排序:

db.workouts.aggregate({
 $match: { user_id: ObjectId(".....") }
},
{
 $project: { 
        '20': { $cond: [ {$gt: [ "$avg_intensity", 20]} , '$total_volume', 0] }
    }    
 })

仅当avg_intensity在一定范围内时，我才需要获取该值.然后，我将对投影结果进行分组和求和.

I need to get the value only if the avg_intensity is inside a certain range. I will then group and sum on the projection result.

我想做的是应用$ gt和$ lt过滤器，但没有成功.

What I am trying to do is applying a $gt and $lt filter but with no much success.

db.workouts.aggregate(
{
   $match: { user_id: ObjectId("....") }
},
{
$project: { 
        '20': { $cond: [ [{$gt: [ "$avg_intensity", 20]}, {$lt: [ "$avg_intensity", 25]}] ,    '$total_volume', 0] }
    }    
 })

如何同时应用$ gt和$ lt条件?

How may I apply both $gt and $lt conditions?

推荐答案

在下合并逻辑条件 $cond 运算符，然后使用/包装条件> $and 运算符:

To combine logical conditions under a $cond operator then wrap the conditions with an $and operator:

db.workouts.aggregate([
    { "$match": { "user_id": ObjectId("....") }},
    { "$project": { 
       "20": { "$cond": [
           { "$and": [ 
               { "$gt": [ "$avg_intensity", 20 ] },
               { "$lt": [ "$avg_intensity", 25 ] }
           ]},    
           "$total_volume", 
           0
       ]}
   }}
])

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