Fetch multiple documents in MongoDB query with OR condition?

To fetch multiple documents in MongoDB using OR condition, use the $or operator which performs a logical OR operation on an array of expressions and selects documents that satisfy at least one of the expressions.

Syntax

db.collection.find({
    $or: [
        { field1: value1 },
        { field2: value2 },
        { field3: value3 }
    ]
});

Sample Data

db.demo362.insertMany([
    { "ClientName": "John", "ClientProject": "School Management System" },
    { "ClientName": "David", "ClientProject": "Library Management System" },
    { "ClientName": "Mike", "ClientProject": "Event Tracker" },
    { "ClientName": "Carol", "ClientProject": "Hospital Management System" }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e56a77454a481fef8ec7a1c"),
        ObjectId("5e56a78454a481fef8ec7a1d"),
        ObjectId("5e56a7a054a481fef8ec7a1e"),
        ObjectId("5e56a7b754a481fef8ec7a1f")
    ]
}

Display all documents from the collection ?

db.demo362.find();

{ "_id": ObjectId("5e56a77454a481fef8ec7a1c"), "ClientName": "John", "ClientProject": "School Management System" }
{ "_id": ObjectId("5e56a78454a481fef8ec7a1d"), "ClientName": "David", "ClientProject": "Library Management System" }
{ "_id": ObjectId("5e56a7a054a481fef8ec7a1e"), "ClientName": "Mike", "ClientProject": "Event Tracker" }
{ "_id": ObjectId("5e56a7b754a481fef8ec7a1f"), "ClientName": "Carol", "ClientProject": "Hospital Management System" }

Example: Fetch Documents with OR Condition

Fetch documents where ClientName is "John" OR ClientProject is "Event Tracker" ?

db.demo362.find({
    $or: [
        { "ClientName": "John" },
        { "ClientProject": "Event Tracker" }
    ]
});

{ "_id": ObjectId("5e56a77454a481fef8ec7a1c"), "ClientName": "John", "ClientProject": "School Management System" }
{ "_id": ObjectId("5e56a7a054a481fef8ec7a1e"), "ClientName": "Mike", "ClientProject": "Event Tracker" }

Key Points

• The $or operator takes an array of expressions as its value.
• Documents matching any one of the conditions will be returned.
• Use $or when you need flexible matching across different fields or values.

Conclusion

The $or operator enables flexible document retrieval by matching any of the specified conditions. It's essential for queries requiring multiple alternative criteria across different fields.