if amount < 0
, then 0 - amount else
{ $project: {
amount: {
$cond: [
{ $lt: ['$amount', 0] },
{ $subtract: [0, '$amount'] },
'$amount'
]
}}}
if amount < 0
, then 0 - amount else
{ $project: {
amount: {
$cond: [
{ $lt: ['$amount', 0] },
{ $subtract: [0, '$amount'] },
'$amount'
]
}}}