How to map two collections in mongodb using node js

Question

I have doubt how to map two collection in mongodb using mongoclient.I tried it but its not working.how to solve it

group_promotion collection

{ 
    "_id" : ObjectId("5cf7679a0b0bed2e7483b998"), 
    "group_name" : "Latest", 
    "products" : [ObjectId("5cecc161e8c1e73478956333"),ObjectId("5cecc161e8c1e73478956334")]  
}

product collection

{ 
    "_id" : ObjectId("5cecc161e8c1e73478956333"), 
    "product_name" : "bourbon"
},
{ 
    "_id" : ObjectId("5cecc161e8c1e73478956334"), 
    "product_name" : "bour"
}

Expected output:

{   
    "_id" : ObjectId("5cf7679a0b0bed2e7483b998"),   
    "group_name" : "Latest",   
    "products" : [{   
    "_id" : ObjectId("5cecc161e8c1e73478956333"),   
    "product_name" : "bourbon"  
    },{
   "_id" : ObjectId("5cecc161e8c1e73478956334"),   
    "product_name" : "bour"  
   }]    
}

score 3 · Accepted Answer · answered Jun 06 '19 at 04:26

3

You can run $lookup directly on products array to get expected result:

db.group_promotion.aggregate([
    {
        $lookup: {
            from: "product",
            localField: "products",
            foreignField: "_id",
            as: "products"
        }
    }
])

This will take products from an array, find corresponding documents in products collection an overwrite exisiting products array in group_production

answered Jun 06 '19 at 04:26

mickl

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@micki but I have another doubt this scenario can you please see group promotional collection and product collection. – Hari Smith Jun 06 '19 at 04:47
@HariSmith have you opened another question ? – mickl Jun 06 '19 at 04:48
@micki no I have changed my question can you please see for group promotional collection and product collection this scenario how to acheive mapping two collections – Hari Smith Jun 06 '19 at 04:50
@micki sorry I wrong edit data .I will correct and updated it.can you please tell me this scenerio how to achieve it. – Hari Smith Jun 06 '19 at 05:17
@HariSmith just try the same query, it should work work one to many relationship as well – mickl Jun 06 '19 at 05:17
@micki ok thanks for u comment .I wll tried it – Hari Smith Jun 06 '19 at 05:18
1

@micki thanks for your solution this its working fine. – Hari Smith Jun 06 '19 at 05:52

How to map two collections in mongodb using node js

1 Answers1