Elasticsearch nested sort based on minimum values of child of child arrays - sorting

Question

I've two orders and these orders have multiple shipments and shipments have multiple products.
How can I sort the orders based on the minimum product.quantity in a shipment?
For example. When ordering ascending, orderNo = 2 should be listed first because it has a shipment that contains a product.quantity=1. (This is the minimum value among all product.quantity values. (productName doesn't matter)
{
"orders": [
{
"orderNo": "1",
"shipments": [
{
"products": [
{
"productName": "AAA",
"quantity": "2"
},
{
"productName": "AAA",
"quantity": "2"
}
]
},
{
"products": [
{
"productName": "AAA",
"quantity": "3"
},
{
"productName": "AAA",
"quantity": "6"
}
]
}
]
},
{
"orderNo": "2",
"shipments": [
{
"products": [
{
"productName": "AAA",
"quantity": "1"
},
{
"productName": "AAA",
"quantity": "6"
}
]
},
{
"products": [
{
"productName": "AAA",
"quantity": "4"
},
{
"productName": "AAA",
"quantity": "5"
}
]
}
]
}
]
}

Answer 1

Assuming that each order is a separate document, you could create an order-focused index where both shipments and products are nested fields to prevent array flattening.
The minimal index mapping could then look like:
PUT orders
{
"mappings": {
"properties": {
"shipments": {
"type": "nested",
"properties": {
"products": {
"type": "nested"
}
}
}
}
}
}
The next step is to ensure the quantity is always numeric -- not a string. When that's done, insert said docs:
POST orders/_doc
{"orderNo":"1","shipments":[{"products":[{"productName":"AAA","quantity":2},{"productName":"AAA","quantity":2}]},{"products":[{"productName":"AAA","quantity":3},{"productName":"AAA","quantity":6}]}]}
POST orders/_doc
{"orderNo":"2","shipments":[{"products":[{"productName":"AAA","quantity":1},{"productName":"AAA","quantity":6}]},{"products":[{"productName":"AAA","quantity":4},{"productName":"AAA","quantity":5}]}]}
Finally, you can use nested sorting:
POST orders/_search
{
"sort": [
{
"shipments.products.quantity": {
"nested": {
"path": "shipments.products"
},
"order": "asc"
}
}
]
}
Tip: To make the query even more useful, you could introduce sorted inner_hits to not only sort the top-level orders but also the individual products enclosed in a given order. These inner hits need a nested query so you could simply add a non-negative condition on shipments.products.quantity.
When you combine this query with the above sort and restrict the response to only relevant attributes with filter_path:
POST orders/_search?filter_path=hits.hits._id,hits.hits._source.orderNo,hits.hits.inner_hits.*.hits.hits._source
{
"_source": ["orderNo", "non_negative_quantities"],
"query": {
"nested": {
"path": "shipments.products",
"inner_hits": {
"name": "non_negative_quantities",
"sort": {
"shipments.products.quantity": "asc"
}
},
"query": {
"range": {
"shipments.products.quantity": {
"gte": 0
}
}
}
}
},
"sort": [
{
"shipments.products.quantity": {
"nested": {
"path": "shipments.products"
},
"order": "asc"
}
}
]
}
you'll end up with both sorted orders AND sorted products:
{
"hits" : {
"hits" : [
{
"_id" : "gVc0BHgBly0XYOUcZ4vd",
"_source" : {
"orderNo" : "2" <---
},
"inner_hits" : {
"non_negative_quantities" : {
"hits" : {
"hits" : [
{
"_source" : {
"quantity" : 1, <---
"productName" : "AAA"
}
},
{
"_source" : {
"quantity" : 4, <---
"productName" : "AAA"
}
},
{
"_source" : {
"quantity" : 5, <---
"productName" : "AAA"
}
}
]
}
}
}
},
{
"_id" : "gFc0BHgBly0XYOUcYosz",
"_source" : {
"orderNo" : "1"
},
"inner_hits" : {
"non_negative_quantities" : {
"hits" : {
"hits" : [
{
"_source" : {
"quantity" : 2,
"productName" : "AAA"
}
},
{
"_source" : {
"quantity" : 2,
"productName" : "AAA"
}
},
{
"_source" : {
"quantity" : 3,
"productName" : "AAA"
}
}
]
}
}
}
}
]
}
}