mongoDB聚合查询中$unwind为什么拆分的不彻底

2025-05-08 06:02:22
推荐回答(2个)
回答1:

mongodb中使用aggregate可以返回数组字段数组的指定索引的元素参考语句: {$match:{'duid':15}}, {$project:{duid:1,"default":1}}, {$unwind:"$default.styles"}, {$match:{'default.styles.status':1}}, {$group:{_id:"$_id","defaults":{$push:"$default.styles"}}} 解释: 1:过滤数据{$match:{'duid':15}} 2:获取想要的列{$project:{duid:1,"default":1}} 3:获取展开后数组字段{$unwind:"$default.styles"} 4:条件查询数组元素{$match:{'default.styles.status':1}} 5:分组后保存结果{$group:{_id:"$_id","defaults":{$push:"$default.styles"}}}

回答2:

mongodb中使用aggregate可以返回数组字段数组的指定索引的元素参考语句: {$match:{'duid':15}}, {$project:{duid:1,"default":1}}, {$unwind:"$default.styles"}, {$match:{'default.styles.status':1}}, {$group:{_id:"$_id","defaults":{$push:"$default.styles"}}} 解释: 1:过滤数据{$match:{'duid':15}} 2:获取想要的列{$project:{duid:1,"default":1}} 3:获取展开后数组字段{$unwind:"$default.styles"} 4:条件查询数组元素{$match:{'default.styles.status':1}} 5:分组后保存结果{$group:{_id:"$_id","defaults":{$push:"$default.styles"}}}
mongodb中使用aggregate可以返回数组字段数组的指定索引的元素参考语句: {$match:{'duid':15}}, {$project:{duid:1,"default":1}}, {$unwind:"$default.styles"}, {$match:{'default.styles.status':1}}, {$group:{_id:"$_id","defaults":{$push:"$default.styles"}}} 解释: 1:过滤数据{$match:{'duid':15}} 2:获取想要的列{$project:{duid:1,"default":1}} 3:获取展开后数组字段{$unwind:"$default.styles"} 4:条件查询数组元素{$match:{'default.styles.status':1}} 5:分组后保存结果{$group:{_id:"$_id","defaults":{$push:"$default.styles"}}}