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Query for documents where array size is greater than 1 in MongoDB?
You can use length to query for documents where array size is greater than 1:
db.yourCollectionName.find({$where:"this.yourArrayDocumentName.length > 1"}).pretty();To understand the above syntax, let us create a collection with some documents. The query is as follows to create a collection with documents:
>db.arrayLengthGreaterThanOne.insertOne({"StudentName":"Larry","StudentTechnicalSubje
ct":["Java","C","C++"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6d6c4c0c3d5054b766a76a")
}
>db.arrayLengthGreaterThanOne.insertOne({"StudentName":"Maxwell","StudentTechnicalSu
bject":["MongoDB"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6d6c660c3d5054b766a76b")
}
>db.arrayLengthGreaterThanOne.insertOne({"StudentName":"Maxwell","StudentTechnicalSu
bject":["MySQL","SQL Server","PL/SQL"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6d6c800c3d5054b766a76c")
}Display all documents from a collection with the help of find() method. The query is as follows:
> db.arrayLengthGreaterThanOne.find().pretty();
The following is the output:
{
"_id" : ObjectId("5c6d6c4c0c3d5054b766a76a"),
"StudentName" : "Larry",
"StudentTechnicalSubject" : [
"Java",
"C",
"C++"
]
}
{
"_id" : ObjectId("5c6d6c660c3d5054b766a76b"),
"StudentName" : "Maxwell",
"StudentTechnicalSubject" : [
"MongoDB"
]
}
{
"_id" : ObjectId("5c6d6c800c3d5054b766a76c"),
"StudentName" : "Maxwell",
"StudentTechnicalSubject" : [
"MySQL",
"SQL Server",
"PL/SQL"
]
}Here is the query for documents where array size is greater than 1. The below query will give all documents where array size is greater than 1:
> db.arrayLengthGreaterThanOne.find({$where:"this.StudentTechnicalSubject.length > 1"}).pretty();The following is the output:
{
"_id" : ObjectId("5c6d6c4c0c3d5054b766a76a"),
"StudentName" : "Larry",
"StudentTechnicalSubject" : [
"Java",
"C",
"C++"
]
}
{
"_id" : ObjectId("5c6d6c800c3d5054b766a76c"),
"StudentName" : "Maxwell",
"StudentTechnicalSubject" : [
"MySQL",
"SQL Server",
"PL/SQL"
]
}
Updated on: 30-Jul-2019
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