According
to MongoDb docs, $cond "evaluates a Boolean expression to return one of
the two specified return expressions".
Syntax:
{$cond: { if: <expression>,
then: <true>,
else: <false>
}
}
OR
{$cond: [<expression>,
<true>, <false>] }
Example
for MongoDb if else statement
db.customers.aggregate(
[{
$project:
{
C_Id: 1,
C_Type:
{
$cond: {
if: { $gte: [ "$C_Id", "IT
"]
},
then: "N_Customer",
else: "VIP_Customer"
}
}
}
}]
)
For more detail, go to