Aggregations on an array in a nested query - elasticsearch

Question

I am trying to query for all Users that have at least one color in common with a particular User and I have been able to do that however I am unable to figure out how to aggregate my results so that I can get a the user along with the colors that they have in common.
Part of my document for a sample user is as follows:
{
// ... other fields
"colors" : [
{
"id" : 1,
"name" : "Green"
},
{
"id" : 7,
"name" : "Blue"
}
]
}
This is my query for getting the colors in common with another User that has the colors Red, Orange and Green:
{
"query": {
"nested": {
"path": "colors",
"scoreMode": "sum",
"query": {
"function_score": {
"filter": {
"terms": {
"colors.name": [
"Red","Orange","Green"
]
}
},
"functions": [
// Functions here for custom scoring
]
}
}
}
}
}
How can I aggregate the Users with the colors in common?

Answer 1

You need to use nested aggregation, then apply filter aggregation for colors and finally use top hits to get the matching colors. I am using source filtering to get only color value
This is the query
{
"size": 0,
"query": {
"nested": {
"path": "colors",
"query": {
"terms": {
"colors.color": [
"green",
"red"
]
}
}
}
},
"aggs": {
"user": {
"terms": { <----get users with unique name or user_id
"field": "name",
"size": 10
},
"aggs": {
"nested_color_path": { <---go inside nested documents
"nested": {
"path": "colors"
},
"aggs": {
"match_color": {
"filter": { <--- use the filter to match for colors
"terms": {
"colors.color": [
"green",
"red"
]
}
},
"aggs": {
"get_match_color": { <--- use this to get matched color
"top_hits": {
"size": 10,
"_source": {
"include": "name"
}
}
}
}
}
}
}
}
}
}
}

Answer 2

You have to use nested aggregations to achieve this. See the query below:
POST <index>/<type>/_search
{
"query": {
"nested": {
"path": "colors",
"query": {
"terms": {
"colors.name": [
"Red",
"Orange",
"Green"
]
}
}
}
},
"aggs": {
"users_with_common_colors": {
"terms": {
"field": "user_id",
"size": 0,
"order": {
"color_distribution>common": "desc" <-- This will sort the users in descending order of number of common colors
}
},
"aggs": {
"color_distribution": {
"nested": {
"path": "colors"
},
"aggs": {
"common": {
"filter": {
"terms": {
"colors.name": [
"Red",
"Orange",
"Green"
]
}
},
"aggs": {
"colors": {
"terms": {
"field": "colors.name",
"size": 0
}
}
}
}
}
}
}
}
}
}