Description:
Each customer object includes a name field.
A line object is comprised of the following fields:
inLine- an array of customerscurrentCustomer- a customer objectprocessed- an array of customers
The 'line' collection stores documents representing line objects.
Issue at Hand:
I am working on implementing a process that includes the following steps:
- Add
currentCustomerto theprocessedarray - Assign the 1st element in
inLinetocurrentCustomer - Remove the 1st element from
inLine
Ensuring atomicity is crucial as the new value depends on the previous state of another field.
Approaches Tried:
Initial Attempt
db.collection('line').findOneAndUpdate({
_id: new ObjectId(lineId),
}, {
$set: {
currentCustomer: '$inLine.0',
},
$pop: {
inLine: -1,
},
$push: {
processed: '$currentCustomer',
},
});
However, the result was assigning strings like "$inLine.0" and "$currentCustomer" instead of actual values.
Aggregation Method
db.collection('line').findOneAndUpdate({
_id: new ObjectId(lineId),
}, [{
$set: {
currentCustomer: '$inLine.0',
},
$pop: {
inLine: -1,
},
$push: {
processed: '$currentCustomer',
},
}]);
This approach resulted in an error stating that a pipeline stage must contain exactly one field.
Multi-stage Aggregation Strategy
db.collection('line').findOneAndUpdate({
_id: new ObjectId(lineId),
}, [{
$set: {
currentCustomer: '$inLine.0',
},
}, {
$pop: {
inLine: -1,
},
}, {
$push: {
processed: '$currentCustomer',
},
}]);
Unfortunately, using $pop and $push led to errors of unrecognized pipeline stage names.
Efforts to solely utilize $set stages were unsuccessful and resulted in complex code that still did not resolve the issue.