w4_1_MongoosePopulation

Mongoose Population
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MongoDB and Relations
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-> NoSQL databases like MongoDB do not explicitly support relations like the sql databases;
-> All documents are normally expected to be self-contained;
-> However you can store references to other documents within a documnet by using ObjectIds.
-> Mongoose does not have joins;

Mongoose Population
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-> Population is the process of automatically replacing specified paths within a document with documnets from
another collection;
-> This is where the cross-reference with ObjectIds helps;

Populating the Documents
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Dishes.find({})
.populate('comments.postedBy') //postedBy is the field the comments sub-document and mongoose extracts it 
//before it sends information back to the user;
.exec(function(err, dish) {
if(err) throw err;
 res.json(dish);
});
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