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Remove and update the existing record in MongoDB?
You can use only $pull operator that removes and updates the existing record in MongoDB. Let us first create a collection with documents −
> db.removeDemo.insertOne(
... {
... "UserName" : "Larry",
... "UserDetails" : [
... {
... "_id" : 101,
... "UserEmailId" : "976Larry@gmail.com",
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc7f9f88f9e6ff3eb0ce446")
}
> db.removeDemo.insertOne(
... {
... "UserName" : "Mike",
... "UserDetails" : [
... {
... "_id" : 102,
... "UserEmailId" : "Mike121@gmail.com",
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc7f9f98f9e6ff3eb0ce447")
}Following is the query to display all documents from a collection with the help of find() method −
> db.removeDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cc7f9f88f9e6ff3eb0ce446"),
"UserName" : "Larry",
"UserDetails" : [
{
"_id" : 101,
"UserEmailId" : "976Larry@gmail.com"
}
]
}
{
"_id" : ObjectId("5cc7f9f98f9e6ff3eb0ce447"),
"UserName" : "Mike",
"UserDetails" : [
{
"_id" : 102,
"UserEmailId" : "Mike121@gmail.com"
}
]
}Let us now implement the $pull query to remove and update the existing record −
> db.removeDemo.update(
... {"_id": ObjectId("5cc7f9f98f9e6ff3eb0ce447")},
... { "$pull": { "UserDetails": {"_id": 102}}}
... );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us display the documents from the collection in order to check the objects have been removed or not −
> db.removeDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cc7f9f88f9e6ff3eb0ce446"),
"UserName" : "Larry",
"UserDetails" : [
{
"_id" : 101,
"UserEmailId" : "976Larry@gmail.com"
}
]
}
{
"_id" : ObjectId("5cc7f9f98f9e6ff3eb0ce447"),
"UserName" : "Mike",
"UserDetails" : [ ]
}
Updated on: 30-Jul-2019
104 Views
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