databasemongodbnosqlaggregatemongo-shell
MongoDB aggregate returning an empty array
So, my problem is, that in MongoDB that .aggregate() function is not working
Heres some pictures:
You can see what a tried on the first picture
Solution
When using "$lookup", it's important that both "localField" values and "foreignField" values have the same type.
In this case, "localField" is a string and "foreignField" is an ObjectId.
It's probably best for queries to use ObjectId's for both.
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