Embedded Documents in MongoDB - mongodb

Question

I'm having trouble understanding exactly how Embedded Documents are enforced in a soft schema such as MongoDB. if given a data-model like so:
User{
UserId:
Email:
Phone:
Reviews{
Rating:
Comment:
}//End reviews
}
Does this mean every User Document has only one review or that this is the format in which all reviews will be for a User?
Perhaps a more relational model of this would be the folloiwng:
User{
UserId:
Phone:
Email:
}
Reviews{
User:<UserID>
Rating:
Comment:
}
I know using references means a slower query but I don't understand how Embedded Documents would allow for multiple reviews.

Answer 1

In the case of having multiple document for the same user, MongoDB adds an unique _Id to the document every time you add a new document, so this wokrks good when you are adding multiple documents for the same user and as #wdberkeley stated, MongoDB does not enforce a schema,
"User" {
"UserId": "johndoe"
"Email": "johndoe#yahoo.com"
"Phone": "555-44444"
"Review"{
"Rating": "5"
"Comment": "this is my first comment"
}
}
"User" {
"UserId": "johndoe"
"Email": "johndoe#yahoo.com"
"Phone": "555-44444"
"Review"{
"Rating": "5"
"Comment": "this is my second comment"
}
}
"User" {
"UserId": "johndoe"
"Email": "johndoe#yahoo.com"
"Phone": "555-44444"
"Review"{
"Rating": "5"
"Comment": "this is my third comment"
}
}
In the case of one document for one user with multiple reviews, this can work fine too, can always get the document and add append reviews to it and call db.update() on the document,
"User" {
"UserId": "johndoe"
"Email": "johndoe#yahoo.com"
"Phone": "555-44444"
"Reviews"{[
{
"Rating": "5"
"Comment": "this is my first comment"
},
{
"Rating": "5"
"Comment": "this is my second comment"
},
{
"Rating": "5"
"Comment": "this is my third comment"
}
]}
}

Answer 2

Are you talking about how this is enforced in MongoDB or in an ODM like Mongoose? For MongoDB, the answer it simple: MongoDB doesn't enforce a schema. You can have all three of the following documents in a MongoDB collection:
{
"reviews" : {
"rating" : 9001,
"comment" : "nice scenery"
}
}
{
"reviews" : [
{
"rating" : [2, 4, 5],
"comment" : 19
},
{
"rating" : -845,
"comment" : "Powerful stuff"
}
]
}
{
"reviews" : "no"
}
In an ODM that enforces a schema application side, your notation is closest to something that would mean each document should have one reviews subdocument.