Question:

I am using the gem <a href="https://github.com/elasticsearch/elasticsearch-rails" rel="nofollow">elasticsearch-rails</a> to retrieve data from elasticsearch in a dynamic way, meaning that the result can have none or multiple aggregations depending on users choices.

Imagine a response like this:

(...) "aggregations"=> {"agg_insignia_id"=> {"buckets"=> [{"key"=>1, "key_as_string"=>"1", "doc_count"=>32156, "agg_chain_id"=> {"buckets"=> [{"key"=>9, "key_as_string"=>"9", "doc_count"=>23079, "agg_store_id"=> {"buckets"=> [{"key"=>450, "key_as_string"=>"450", "doc_count"=>145, "agg_value"=>{"value"=>1785.13}}, {"key"=>349, "key_as_string"=>"349", "doc_count"=>143, "agg_value"=>{"value"=>1690.37}},

How can I transform that data in a tabular data? like

| insignia_id | chain_id | store_id | value | | 1 | 9 | 450 | 1785.13 | | 1 | 9 | 349 | 1690.37 | (...)

EDIT :: Being clear on the response I am looking for, two choices here: Array (simple) or Array of hashes.

<strong>Array style:</strong> [[insignia_id, chain_id, store_id, value], [1,9,450,1785.13], [1,9,349,1690.37],...]

<strong>Array of Hashes style:</strong> [{insignia_id => 1, chain_id => 9, store_id => 450, value => 1785.13}, {insignia_id => 1, chain_id => 9, store_id => 450, value => 1690.37 }]

The later is more like an activerecord style...

ok, so I came up with a solution for an array response.

Firstly added a helper for what comes ahead...

class Hash def deep_find(key, object=self, found=nil) if object.respond_to?(:key?) && object.key?(key) return object[key] elsif object.is_a? Enumerable object.find { |*a| found = deep_find(key, a.last) } return found end end end

now for the array algorithm (added in a concern):

def self.to_table_array(data, aggs, final_table = nil, row = []) final_table = [aggs.keys] if final_table.nil? hash_tree = data.deep_find(aggs.keys.first) if aggs.values.uniq.length == 1 && aggs.values.uniq == [:data] aggs.keys.each do |agg| row << data[agg]["value"] end final_table << row else hash_tree["buckets"].each_with_index do |h, index| row.pop if index > 0 aggs.shift if index == 0 row << h["key_as_string"] final_table = to_table_array(h, aggs.clone, final_table, row.clone) end end final_table end

The call for this method could be made like this:

#_fields = { "insignia_id" => :row, "chain_id" => :row, "store_id"=> :row, "value" => : data } #res.response => Elasticsearch response result = to_table_array(res.response, _fields)

There are some things quite specific to this case like you can see on this _fields variable. Also I'm assuming each aggregation has the name of the term itself. The rest is quite the same for every possible case.

A result of an array of hashes is pretty simple from here just by replacing few lines.

I put a lot of efford in this. Hope this helps someone else other than me.