MongoDB update $pull operator is not removing item from array

Question

I have a collection in MongoDB. And want to remove an item from array.

My "users" collection is an array of objects.

When I type:

db.users.find({"tasks.task_id" : "h58sjIdj3jJZ"}).pretty()

in mongo shell, I get this result:

{
  "_id" : ObjectId("5955b45b7a4bf40544019359"),
  "profile" : {
    "name" : "Morning bay",
    "email" : "[email protected]",
    "phone" : "+1-641-155-88-84",
    "description" : "Lorem ipsum dolor sit amet, consectetur adipisicing elit"
  },
  "tasks" : [
    {
      "task_id" : "h58sjIdj3jJY",
      "time" : "11:15 AM",
      "date" : "07/01/2017",
      "description" : "Make 1st call to John White"
    },
    {
      "task_id" : "h58sjIdj3jJZ",
      "time" : "14:30 PM",
      "date" : "07/09/2017",
      "description" : "Send certificate and make Another call to J.White"
    }
  ],
  "progress" : [
    {
      "isActive" : "",
      "description" : ""
    }
  ]
}

So, every item in my collection looks like this. And it's ok.

But now I want to remove one item from "tasks" array in one of users items.

I type:

db.users.update({}, {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}});

an get this result:

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

I read documentation and examples in it look similar, so I don't understand where is an error.

Can you add { multi:true } as 3rd argument of your update ? db.users.update({}, {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}}, { multi:true } ); — Julien TASSIN
– Julien TASSIN, Commented Jul 3, 2017 at 18:44

djaszczurowski · Accepted Answer · 2017-07-03 18:45:20Z

2

you're using {} in update search query what by default means find any document, and then you're modifying its tasks list {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}}.

So, probably another document is being modified (which may or may not contain task of id h58sjIdj3jJZ but in that case its irrelevant whether it has it or not)

You have 2 options: use:

db.users.update({}, {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}}, { multi: true });

what eventually touches every document in db,

OR

make search query more specific (provide id or look for item with task_id in tasks)

db.users.update({ "tasks.task_id": "h58sjIdj3jJZ"}, {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}});

answered Jul 3, 2017 at 18:45

djaszczurowski

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1 Comment

alexfrize Over a year ago

Yes! I used db.users.update({ "tasks.task_id": "h58sjIdj3jJZ"}, {$pull : {"tasks" : {"task_id" : "h58sjIdj3jJZ"}}}) and it helped! Thank you!

Mathias Rodriguez · Accepted Answer · 2017-07-03 18:43:25Z

0

I tested it on a MongoDB Terminal Online and your query correctly pulled the document.

Here is the output.

Are you experiencing this issue with the shell or using an ODM (like Mongoose)?

answered Jul 3, 2017 at 18:43

Mathias Rodriguez

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1 Comment

alexfrize Over a year ago

I use MongoJS instead of Mongoose. And yes, there is the same issue. It doesn't remove an item from tasks array.

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