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Filter documents in MongoDB if all keys exist as fields?
For this, use $all, that would find documents containing all of the elements in an array like "keys". Let us first create a collection with documents −
> db.demo17.insertOne({"ListOfSubject":["MySQL","MongoDB","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e13847255d0fc6657d21f0a")
}
> db.demo17.insertOne({"ListOfSubject":["C","Python","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e13847e55d0fc6657d21f0b")
}
> db.demo17.insertOne({"ListOfSubject":["C++","MongoDB","PL/SQL"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e13849255d0fc6657d21f0c")
}Following is the query to display all documents from a collection with the help of find() method −
> db.demo17.find();
This will produce the following output −
{ "_id" : ObjectId("5e13847255d0fc6657d21f0a"), "ListOfSubject" : [ "MySQL", "MongoDB", "Java" ] }
{ "_id" : ObjectId("5e13847e55d0fc6657d21f0b"), "ListOfSubject" : [ "C", "Python", "Java" ] }
{ "_id" : ObjectId("5e13849255d0fc6657d21f0c"), "ListOfSubject" : [ "C++", "MongoDB", "PL/SQL" ] }Here is the query to filter documents if all keys exist as fields −
> db.demo17.find({"ListOfSubject": { "$all": ["C++","PL/SQL","MongoDB"] } });This will produce the following output −
{ "_id" : ObjectId("5e13849255d0fc6657d21f0c"), "ListOfSubject" : [ "C++", "MongoDB",
"PL/SQL" ] }
Updated on: 01-Apr-2020
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