mongo-doc

如何将List打平，放到set中

db.collection.aggregate([
    {$group:{
       _id: null,
       selectedTags: { $push: '$tags' }      
    }},
    {$project: {
        selectedTags: { $reduce: {
            input: "$selectedTags",
            initialValue: [],
            in: {$setUnion : ["$$value", "$$this"]}
        }}
    }}
])

[$addFields: [userIds: [$reduce: [input: '$userIdLists', initialValue: [], in: [$setUnion: ['$$value', '$$this']]]]]],

join on orgId

{$addFields:{'totalUser':[{orgId:885, num:100},{orgId:966,num:101}]}},
{$addFields:{'totalUser': {$filter:{input:'$totalUser',as:'item',cond:{$eq:['$$item.orgId','$orgId']}}}}},
{$addFields:{'totalUser': {$arrayElemAt:['$totalUser',0]}}},
{$addFields:{'totalUser': '$totalUser.num'}},