Flatten nested JSON using jq

Question

I'd like to flatten a nested json object, e.g. {"a":{"b":1}} to {"a.b":1} in order to digest it in solr.

I have 11 TB of json files which are both nested and contains dots in field names, meaning not elasticsearch (dots) nor solr (nested without the _childDocument_ notation) can digest it as is.

The other solutions would be to replace dots in the field names with underscores and push it to elasticsearch, but I have far better experience with solr therefore I prefer the flatten solution (unless solr can digest those nested jsons as is??).

I will prefer elasticsearch only if the digestion process will take far less time than solr, because my priority is digesting as fast as I can (thus I chose jq instead of scripting it in python).

Kindly help.

EDIT:

I think the pair of examples 3&4 solves this for me: https://lucidworks.com/blog/2014/08/12/indexing-custom-json-data/

I'll try soon.

Answer 1

You can also use the following jq command to flatten nested JSON objects in this manner:

[leaf_paths as $path | {"key": $path | join("."), "value": getpath($path)}] | from_entries

The way it works is: leaf_paths returns a stream of arrays which represent the paths on the given JSON document at which "leaf elements" appear, that is, elements which do not have child elements, such as numbers, strings and booleans. We pipe that stream into objects with key and value properties, where key contains the elements of the path array as a string joined by dots and value contains the element at that path. Finally, we put the entire thing in an array and run from_entries on it, which transforms an array of {key, value} objects into an object containing those key-value pairs.