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$and (aggregation)

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Definition

$and

Evaluates one or more expressions and returns true if all of the expressions are true or if evoked with no argument expressions. Otherwise, $and returns false.

$and has the following syntax:

{ $and: [ <expression1>, <expression2>, ... ] }

For more information on expressions, see Expressions.

Behavior

$and uses short-circuit logic: the operation stops evaluation after encountering the first false expression.

In addition to the false boolean value, $and evaluates as false the following: null, 0, and undefined values. The $and evaluates all other values as true, including non-zero numeric values and arrays.

Example   Result
{ $and: [ 1, "green" ] }   true
{ $and: [ ] }   true
{ $and: [ [ null ], [ false ], [ 0 ] ] }   true
{ $and: [ null, true ] }   false
{ $and: [ 0, true ] }   false

Example

Consider an inventory collection with the following documents:

{ "_id" : 1, "item" : "abc1", description: "product 1", qty: 300 }
{ "_id" : 2, "item" : "abc2", description: "product 2", qty: 200 }
{ "_id" : 3, "item" : "xyz1", description: "product 3", qty: 250 }
{ "_id" : 4, "item" : "VWZ1", description: "product 4", qty: 300 }
{ "_id" : 5, "item" : "VWZ2", description: "product 5", qty: 180 }

The following operation uses the $and operator to determine if qty is greater than 100 and less than 250:

db.inventory.aggregate(
   [
     {
       $project:
          {
            item: 1,
            qty: 1,
            result: { $and: [ { $gt: [ "$qty", 100 ] }, { $lt: [ "$qty", 250 ] } ] }
          }
     }
   ]
)

The operation returns the following results:

{ "_id" : 1, "item" : "abc1", "result" : false }
{ "_id" : 2, "item" : "abc2", "result" : true }
{ "_id" : 3, "item" : "xyz1", "result" : false }
{ "_id" : 4, "item" : "VWZ1", "result" : false }
{ "_id" : 5, "item" : "VWZ2", "result" : true }