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Check for existing documents/embedded documents in MongoDB
To check for existing documents/embedded documents, use $exists in MongoDB. Let us create a collection with documents −
> db.demo322.insertOne(
... {'id':1001,
... 'details':[{'Score':10000,Name:"Bob"},
... {'Score':98000,Name:"Sam"}
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e5113e2f8647eb59e56206c")
}
> db.demo322.insertOne(
... {'id':10002,
... 'details':[{'Score':9000},
... {'Score':91000}
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e5113faf8647eb59e56206d")
}Display all documents from a collection with the help of find() method −
> db.demo322.find();
This will produce the following output −
{
"_id" : ObjectId("5e5113e2f8647eb59e56206c"), "id" : 1001, "details" : [
{ "Score" : 10000, "Name" : "Bob" }, { "Score" : 98000, "Name" : "Sam" }
]
}
{
"_id" : ObjectId("5e5113faf8647eb59e56206d"), "id" : 10002, "details" : [
{ "Score" : 9000 }, { "Score" : 91000 }
]
}Following is the query to check for existing documents/embedded documents −
> db.demo322.find({"details.Name":{$exists:true}}).count() > 0;This will produce the following output −
True
Updated on: 02-Apr-2020
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