Deleting a field with $unset operation it just converting it to a null value

Question

I'm trying to delete some fields on my mongodb database but instead the fields are just getting mutated to a null value and that's an issue because when fetching data im using loops and they get broken passing true null value ... for deleting data i'm using the following :

 User.updateOne({_id : user._id } ,{ $unset :{ "days.0.tasks.0" = "" })

what i'm getting :

Is there a way to delete entirely the objects inside the tasks array?

@FelDev as you can see on the picture yeah – user121548789 Aug 23 '19 at 16:16 — user121548789, Aug 23 '19 at 16:16

score 0 · Accepted Answer · edited Aug 23 '19 at 21:48

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$unset is not working as you'd expect it because you are using it on an element inside an array. Removing the element at position 0 means shifting all other elements in the array. To prevent messing with those other elements, $unset is setting the element at position 0 to null.

MongoDB docs

I suggest using the $pull operator to delete specific elements from an array or use $pop for the first / last items .

OR :

you can get the user tasks array and splice it then push it back using $set operator.

edited Aug 23 '19 at 21:48

user121548789

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answered Aug 23 '19 at 16:33

Félix Paradis

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Thank you but $pop removes only the first or last element of an array i need to delete a specific item on the array – user121548789 Aug 23 '19 at 16:37
How about $pull then? – Félix Paradis Aug 23 '19 at 16:38
$pull requires you to specify a condition, though. – Félix Paradis Aug 23 '19 at 16:39
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Else I think you'll find what you're looking for here: https://stackoverflow.com/questions/4588303/in-mongodb-how-do-you-remove-an-array-element-by-its-index – Félix Paradis Aug 23 '19 at 16:41
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hey i actually figured out a way from the answer that you mentioned and some personal efforts ...i will edit your answer so i can accept it – user121548789 Aug 23 '19 at 17:54

Deleting a field with $unset operation it just converting it to a null value

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