$and (aggregation)¶

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Definition
Behavior
Example

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:

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{ $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¶

Create an example inventory collection with the following documents:

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db.inventory.insertMany([
   { "_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:

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

The operation returns the following results:

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

← $allElementsTrue (aggregation) $anyElementTrue (aggregation) →