If we consider a database of sold cars from a dealership, each represented by an object with various properties such as model, carId, and salesmanId, how can we efficiently query the total number of cars and unique car models per salesman? Let's look at an example dataset:
{
id: 'randomId',
model: 'Jetta',
carId: 'randomId',
salesmanId: 'salesmenId3'
},
{
id: 'randomId',
model: 'Civic',
carId: 'randomId',
salesmanId: 'salesmenId2'
},
{
id: 'randomId',
model: 'Civic',
carId: 'randomId',
salesmanId: 'salesmenId2'
},
{
id: 'randomId',
model: 'S200',
carId: 'randomId',
salesmanId: 'salesmenId'
},
{
id: 'randomId',
model: 'Jetta',
carId: 'randomId',
salesmanId: 'salesmenId3'
},
{
id: 'randomId',
model: 'Civic',
carId: 'randomId',
salesmanId: 'salesmenId2'
},
...
When querying for a specific salesmanId, like 'salesmenId2', we would expect a result like this:
{
salesmanId: 'salesmenId2',
totalCars: 3,
totalUniqueCars: 1
}
The initial approach to this query involves $match to filter by salesmanId, $group to group by salesmanId and calculate totalCars, and $addToSet to create a list of unique cars. However, the query as it stands currently only returns the total of unique cars. What could be missing in the query logic?