MongoDB query to test if a value is in array?

To check for a specific value, use $in. Let us first create a collection with documents −

> db.testInArray.insertOne({"ListOfNumbers":[10,56,78,90,32]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e04d42df5e889d7a519950d")
}
> db.testInArray.insertOne({"ListOfNumbers":[56,78,91,100]});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e04d588f5e889d7a519950e")
}

Following is the query to display all documents from a collection with the help of find() method −

> db.testInArray.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5e04d42df5e889d7a519950d"),
   "ListOfNumbers" : [
      10,
      56,
      78,
      90,
      32
   ]
}
{
   "_id" : ObjectId("5e04d588f5e889d7a519950e"),
   "ListOfNumbers" : [
      56,
      78,
      91,
      100
   ]
}

Here is the query to test if a value is in array −

> db.testInArray.find({ ListOfNumbers:{ "$in" : [90]} });

This will produce the following output −

{ "_id" : ObjectId("5e04d42df5e889d7a519950d"), "ListOfNumbers" : [ 10, 56, 78, 90, 32 ] }