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MongoDB pull with positional operator?
Use $pull operator along with positional operator($) in MongoDB. Let us first create a collection with documents −
> db.pullWithPositionalOperatorDemo.insertOne(
... {
... _id: 100,
... "StudentDetails": [
... {
... "StudentId": "STU-1",
... "StudentFavouriteSubject": ["MongoDB", "Java"]
... },
... {
... "StudentId": "STU-2",
... "StudentFavouriteSubject": ["PHP", "MySQL"]
... }
... ]
... }
... );
{ "acknowledged" : true, "insertedId" : 100 }Following is the query to display all documents from a collection with the help of find() method −
> db.pullWithPositionalOperatorDemo.find().pretty();
This will produce the following output −
{
"_id" : 100,
"StudentDetails" : [
{
"StudentId" : "STU-1",
"StudentFavouriteSubject" : [
"MongoDB",
"Java"
]
},
{
"StudentId" : "STU-2",
"StudentFavouriteSubject" : [
"PHP",
"MySQL"
]
}
]
}Following is the query to perform pull with positional operator −
> db.pullWithPositionalOperatorDemo.update({
... "StudentDetails" : {
... "$elemMatch" : {
... "StudentId" : "STU-2",
... "StudentFavouriteSubject" : "MySQL"
... }
... }
... }, {
... $pull : {
... "StudentDetails.$.StudentFavouriteSubject" : "MySQL"
... }
... }, {
... multi : true
... });
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us check all documents from the above collection once again −
> db.pullWithPositionalOperatorDemo.find().pretty();
This will produce the following output −
{
"_id" : 100,
"StudentDetails" : [
{
"StudentId" : "STU-1",
"StudentFavouriteSubject" : [
"MongoDB",
"Java"
]
},
{
"StudentId" : "STU-2",
"StudentFavouriteSubject" : [
"PHP"
]
}
]
}
Updated on: 30-Jul-2019
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