Mongo 数组查询计数

Question

Sample Collection

[
 {
  products: [
   {name: 'apple'}, {name: 'mango'}, {name: 'orange'}
  ]
},
 {
  products: [
   {name: 'banna'}, {name: 'grapes'}, {name: 'orange'}
  ]
}
]

I want a query to know if which document contains atleast 2 of my searched products

for example..

collection.find({ products: {$in: ['apple', 'mango', 'durian', 'avocado', 'orange']} })

but this only checks if it contains one of those products. I wanna know if a certain documents containls atleast 2 of the product im searching

Answer 1

You can either add some code so manipulate the query structure or you have to use an aggregation pipeline.

Option 1 (recommended), use the aggregation pipeline with $filter :

let fruits = ['apple', 'mango', 'durian', 'avocado', 'orange'];
collection.aggregate([
    {
        $match: {
            "products.name": {$in: fruits}
        }
    },
    {
        $project: {
            good_products_size: {
                $size: {
                    $filter: {
                        input: "$products",
                        as: "product",
                        cond: {$in: ["$$product.name", fruits]}
                    }
                }
            }
        }
    },
    {
        $match: {
            good_products_size: {$gt: 1}
        }
    }
]);

Option 2 (less recommended imo), generate all possible pairs from the fruits array and use $all :

let fruits = ['apple', 'mango', 'durian', 'avocado', 'orange'];
let queryOrConds = [];

for (let i = 0; i < fruits.length - 1; i++) {
    for (let j = i; j < fruits.length - 1; j++) {
        queryOrConds.push({"products.name": {$all: [fruits[i], fruits[j]]}})
    }
}
collection.find({ $or: queryOrConds })