JOIN two indexes using ElasticSearch Node.js client

[sadiki-dev (sadiki)]

I have two indexes (two collections) , products index and reviews index. The two is linked by productId. The structure of both are :

// products.json
[
    {
        "id": 1,
        "name": "IPhone 11",
        "quantity_stock": 100,
        "description": "description of IPhone 11",
        "manufacturing": {
            "id": 416665497,
            "entreprise": "Apple",
            "country": "USA",
            "address": {
                "zipCode": "10000",
                "state": "New York",
                "street": "Johny 10"
            }
        }
    },
    {
        "id": 2,
        "name": "Samsung 10",
        "quantity_stock": 130,
        "description": "description of Samsung 10",
        "manufacturing": {
            "id": 4545465497,
            "entreprise": "Samsung",
            "country": "Koea",
            "address": {
                "zipCode": "20000",
                "state": "Tokyo",
                "street": "yong ki 645"
            }
        }
    },
    {
        "id": 3,
        "name": "Redmi Note 10",
        "quantity_stock": 80,
        "description": "description of Redmi Note 10",
        "manufacturing": {
            "id": 4545465497,
            "entreprise": "Samsung",
            "country": "China",
            "address": {
                "zipCode": "14000",
                "state": "Pekin",
                "street": "yong ki 10"
            }
        }
    }
]

// reviews.json
[
    {
        "id": 1,
        "rating": 8,
        "productId": 1,
        "comment": "It's an excelent product"
    },
    {
        "id": 2,
        "rating": 1,
        "productId": 1,
        "comment": "It's a bad product"
    },
    {
        "id": 3,
        "rating": 6,
        "productId": 2,
        "comment": "It's a good product"
    }
]

I want to join the two indexes (products and reviews) to have all products linked with their own reviews.

// 👉 Input for One product
{
        "id": 1,
        "name": "IPhone 11",
        "quantity_stock": 100,
        "description": "description of IPhone 11",
        "manufacturing": {
            "id": 416665497,
            "entreprise": "Apple",
            "country": "USA",
            "address": {
                "zipCode": "10000",
                "state": "New York",
                "street": "Johny 10"
            }
        }
    }

// 👉 Desired Output :
{
        "id": 1,
        "name": "IPhone 11",
        "quantity_stock": 100,
        "description": "description of IPhone 11",
        "manufacturing": {
            "id": 416665497,
            "entreprise": "Apple",
            "country": "USA",
            "address": {
                "zipCode": "10000",
                "state": "New York",
                "street": "Johny 10"
            }
        },
// Add This 👇
        "reviews": [
            {
                "id": 1,
                "rating": 8,
                "productId": 1,
                "comment": "It's an excelent product"
            },
            {
                "id": 2,
                "rating": 1,
                "productId": 1,
                "comment": "It's a bad product"
            }
        ]
    }

How I can do a join between two indexes, something like $lookup in MongoDB ?
Please who has any idea or reference to solve this issue.

Kind regards.

[warkolm (Mark Walkom)]

You cannot do this with an Elasticsearch query. You will need to manage the two queries and merging in your code.