我尝试遵循许多线程来解决此问题，但是我无法提出解决方案，也许是因为我是MongoDB的新手。
无论如何，我有2个名为product和product_review的集合，我想在MongoDB中使用Map / Reduce函数将product_review集合中的注释合并到products集合中。公用字段是“名称”。换句话说，我要合并名称下的所有注释，而不必为每个注释重复“名称”字段。
db.products.insertOne( { name : "iPhone 5", Price : 600, company : "Apple"})
db.products.insertOne( { name : "Galaxy Note9", Price : 900, company : "samsung"})
db.products.insertOne( { name : "LG V40 ThinQ", Price : 800, company : “LG”})
db.products.insertOne( { name : “Watch”, Price : 400, company : "Apple"})
db.products.insertOne( { name : "iPhone 7”, Price : 900, company : "Apple"})
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//product_review Collection
db.product_review.insertOne( { name : "Watch", comment: " Great Product")
db.product_review.insertOne( { name : "Watch", comment: " AMAZING”)
db.product_review.insertOne( { name : "iPhone 7", comment: " Not bad”)
db.product_review.insertOne( { name : "iPhone 7", comment: " Expeinsive”)
db.product_review.insertOne( { name : "Galaxy Note9", comment: " Great Product")
db.product_review.insertOne( { name : "Galaxy Note9", comment: " Great Product")
// end of product_review collection.
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The output that I am looking for is as the following. One Name and or many comments without repeating the name with each comment
{name: “Galaxy Note9”, Price: 900, company: “Samsung”, comment: " Great Product”, comment: " Good”, comment: " I like it”}
我应该提一下，我花了4个小时来遵循此代码，但这是行不通的！