"Exploring the depths of MongoDB: Unraveling multiple criteria search

Question

"Exploring the depths of MongoDB: Unraveling multiple criteria search

I have a diverse collection of food entries like this

foods{
{ 
  name: 'rice'
  type: 'Brazilian'
},
{
  name: 'meat'
  type: 'Spanish'
}
,
{
  name: 'Cake'
  type: 'Brazilian'
}

How can I retrieve a specific number of foods for each type in MongoDB? For instance, I want to get a collection (array) of 4 foods for each type.

[
    [
        {
            name: 'rice'
            type: 'Brazilian'
        },
        {
            name: 'meat'
            type: 'Brazilian'
        }       
        {
            name: 'pizza'
            type: 'Brazilian'
        },
        {
            name: 'bread'
            type: 'Brazilian'
        }
    ],

    [
        {
            name: 'beans'
            type: 'spanish'
        },
        {
            name: 'fish'
            type: 'spanish'
        }       
        {
            name: 'chocolare'
            type: 'spanish'
        },
        {
            name: 'ham'
            type: 'spanish'
        }
    ]

]

javascript json mongodb

Answer 1

Answer №1

To achieve the desired outcome, utilize aggregation techniques. Within your aggregation pipeline, the $group operator plays a central role in shaping the result by grouping documents from the input collection based on the type key. Subsequently, you can employ an accumulator operator like $push to construct an array. Consider the following example:

var pipeline = [
    {
        "$group": {
            "_id": "$type",
            "items": {
                "$push": { "name": "$name", "type": "$type" }
            }
        }
    }
]

var result = db.products.aggregate(pipeline).map(function (item){ return item.items });
printjson(result);

Answer 2

To achieve the desired outcome, utilize aggregation techniques. Within your aggregation pipeline, the $group operator plays a central role in shaping the result by grouping documents from the input collection based on the type key. Subsequently, you can employ an accumulator operator like $push to construct an array. Consider the following example:

var pipeline = [
    {
        "$group": {
            "_id": "$type",
            "items": {
                "$push": { "name": "$name", "type": "$type" }
            }
        }
    }
]

var result = db.products.aggregate(pipeline).map(function (item){ return item.items });
printjson(result);

"Exploring the depths of MongoDB: Unraveling multiple criteria search

Answer №1

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