Let say we have a collection transactions which contains some document and documents contain payments which is array of objects.
Now my task is to get the unique types in payments array of every document.
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{
'id':'74656345'
'payments':[
{
'amount': 200,
'type': 'Debit Card'
},
{
'name': 300,
'type': 'Internet Banking'
},
{
'name': 300,
'type': 'Credit Card'
}
],
},
{
'id':'9783475'
'payments':[
{
'amount': 200,
'type': 'Debit Card'
},
{
'name': 300,
'type': 'Internet Banking'
},
{
'name': 300,
'type': 'UPI'
}
],
}
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Expected Result: Debit Card, Internet Banking, Credit Card, UPI
which is unique values of payment types in transctions collection and the MongoDB query for that is given below:
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db.transctions.aggregate(
{'$unwind':'$payments'},
{"$group" : {"_id": "$payments.type"}}
)
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Here we first unwind the data so that every payments array can be converted to objects and then we are grouping the type of payments document in transctions collection. ...