I have 2 collections say, Collection-1, and Collection-2.
Collection-1
{
"_id" : 1,
"myArray" : [ { Key : "KeyVal", price:40 } ]
}
Collection-2
{
"_id" : 1,
"myArray" : [ { Key : "KeyVal", quantity:20 } ]
}
What I am trying is i would like to multiply price and quantity from collection-1 and 2.
To do this, I am joining both the collections using $lookup.
I could able to $unwind the Collection-1 to get the key. The Question is How do I get the Key (foreign Key) from the collection 2?
Am I making fundamental mistakes? Suggestions please. Also please share the link if related question is already asked .
Note: The most important concern is i can't change the collection structure. otherwise i could have make the key as _id and i can proceed further.
