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Remove array elements from MongoDB collection using update() and $pull

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Release: 2023-09-13 16:45:09
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使用 update() 和 $pull 从 MongoDB 集合中删除数组元素

Let us first create a collection containing documents -

> db.removingAnArrayElementDemo.insertOne({"UserMessage":["Hi","Hello","Bye"]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cef97bdef71edecf6a1f6a4")
}
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Display all the documents in the collection with the help of find() method -

> db.removingAnArrayElementDemo.find().pretty();
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Output

{
   "_id" : ObjectId("5cef97bdef71edecf6a1f6a4"),
   "UserMessage" : [
      "Hi",
      "Hello",
      "Bye"
   ]
}
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The following is the query to delete array elements from MongoDB -

> db.removingAnArrayElementDemo.update(
   {_id:ObjectId("5cef97bdef71edecf6a1f6a4")},
   { "$pull": { "UserMessage": "Hello" } }
);
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
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Let’s check the document again:

> db.removingAnArrayElementDemo.find().pretty();
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Output

{
   .
   "_id" : ObjectId("5cef97bdef71edecf6a1f6a4"),
   "UserMessage" : [
      "Hi",
      "Bye"
   ]
}
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source:tutorialspoint.com
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