$ pull mongodb没有删除项目

Question

I have a collection:

//the json.
{
"ItemsToDelete" : [ 
        {
            "placeId" : "ChIJIQBpAG2ahYAR_6128GcTUEo",
            "users" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }, 
        {
            "placeId" : "ChIJIQBpAG2ahYAR_6128GcTUEo",
            "users" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }, 
        {
            "placeId" : "ChIJIQBpAG2ahYAR_6128GcTUEo",
            "users" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }
    ]
}  


{
"ItemsToRemove" : [ 
        {
            "ChIJIQBpAG2ahYAR_6128GcTUEo" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }, 
        {
            "ChIJIQBpAG2ahYAR_6128GcTUEo" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }, 
        {
            "ChIJIQBpAG2ahYAR_6128GcTUEo" : [ 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15"), 
                ObjectId("547e4650f3fb0a022110af15")
            ]
        }
    ]
}

I then run this mongo shell query to pull an item off the array and delete:

db.users.update({"_id":ObjectId("54e664c4e7c3b4d3b5413e39")},{$pull:{ItemsToDelete : {placeId:"ChIJIQBpAG2ahYAR_6128GcTUE"}}},{ multi: true })

The array remains unmodified. Any thoughts why this is failing to $pull?

I have tried 'ItemsToDelete.placeId' but that errors out with: error I receive when doing “ItemsToDelete.placeId” => ‘cannot use the part (ItemsToDelete of ItemsToDelete.placeId) to traverse the element’

Answer 1

You query doesn't pull any item because you are missing o in placeId value.

> db.users.update(
    {"_id":ObjectId("54e664c4e7c3b4d3b5413e39")},
    {$pull:{ItemsToDelete : {placeId:"ChIJIQBpAG2ahYAR_6128GcTUE"}}},
                                                                ^
    { multi: true }
  )

Should be

> db.users.update(
    {"_id":ObjectId("54e664c4e7c3b4d3b5413e39")},
    {$pull:{ItemsToDelete : {placeId:"ChIJIQBpAG2ahYAR_6128GcTUEo"}}},
    { multi: true }
  )

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.users.find().pretty()
{ "_id" : ObjectId("54eac8d51a0c74438c9dea10"), "ItemsToDelete" : [ ] }