Count the number of elements in a MongoDB array using a

Question

Count the number of elements in a MongoDB array using a

Sample Collection

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

I am looking for a query that can determine which document contains at least two of the searched products.

For example..

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

The current query only checks if it contains one of those products. I want to identify documents that have at least two of the searched products in them.

javascript mongodb

Answer 1

Answer №1

To modify the query structure, you can add specific code or utilize an aggregation pipeline.

For Option 1 (recommended), implement 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}
        }
    }
]);

Alternatively, for Option 2 (less recommended in my opinion), you can generate all possible pairs from the fruits array and utilize $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 })

Answer 2

To modify the query structure, you can add specific code or utilize an aggregation pipeline.

For Option 1 (recommended), implement 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}
        }
    }
]);

Alternatively, for Option 2 (less recommended in my opinion), you can generate all possible pairs from the fruits array and utilize $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 })

Count the number of elements in a MongoDB array using a

Answer №1

Similar questions

I am struggling to add a list from these nested functions in Express, but for some reason, the items are not being properly

utilizing loop to incorporate javascript callback

"JavaScript/TypeScript: The Importance of Defining Object Return Types

Retrieving a file stored in MongoDB through GridFS using JavaScript in Node.js

Reveal the functions of one module to another module

Is it possible to create multiple inputs by clicking the div multiple times?

Facing difficulty in uploading image to local server using Froala editor

Developing node.js scripts for configuring an app via the command line interface

Having trouble sending a JavaScript variable to PHP using Ajax

Using Javascript to dynamically add form fields based on the selection made in a combo box

Picture navigation tool

Trouble connecting to MySQL database using Sequelize in Node.js

Modify the href link before submitting the request

Node.js express version 4.13.3 is experiencing an issue where the serveStatic method is not properly serving mp3 or

Tips for aligning an element with another element's position

Transform the MongoDB data in the aggregation pipeline following the $addToSet stage: one set will serve as the keys, while the other set

Hovering over a Raphael animation - What's preventing it from functioning?

Retrieve all elements from an array using jQuery

Google Sheets - Create a randomized list of numerical values (specified quantity) within a certain range (set numbers) that collectively equal a specific total

The error message "Uncaught SyntaxError: Unexpected number" indicates a problem with