JSON schema dump command

A wrapper for jq. Dumps the schemas (as determined by jq) from a JSON document.

A jq wrapper that prints back a high-level view of the schema of a JSON document.

json_schema is a bash script that does two things:

1. List unique paths using valid jq queries that you can then use to retrieve those paths if you wish.
2. Count how many times each unique path occurs in the document.

List the unique paths in a JSON document

Each unique path in the JSON document is printed alongside a count of how many times that unique path occurs in the document.

Count how many times each unique path occurs

For each unique path, a count of occurrences is printed to the left of the path.

The path itself is shown as a valid jq expression that you can then use to access resources at paths you have identified.

Synopsis

Use it like this:

json_schema foo.json

If the contents of foo.json were the following:

{
  "a": "foo",
  "b": "bar",
  "c": [1, 2, 3, {"hello": "world"}, 4, 5],
  "d": []
}

Then that should produce output like this:

  1 .["a"]
  1 .["b"]
  1 .["c"]
  6 .["c"][]
  1 .["c"][]["hello"]
  1 .["d"]

Sample output from NASA near-Earth objects report

This is what json_schema looks like when applied to a larger JSON document.

curl -so near_earth_asteroids.json \
    https://data.nasa.gov/resource/2vr3-k9wn.json

json_schema near_earth_asteroids.json

Then the output should look like:

202 .[]
202 .[]["designation"]
202 .[]["discovery_date"]
181 .[]["h_mag"]
202 .[]["i_deg"]
202 .[]["moid_au"]
202 .[]["orbit_class"]
200 .[]["period_yr"]
202 .[]["pha"]
202 .[]["q_au_1"]
200 .[]["q_au_2"]

As you can see, json_schema presents a compact, high-level view of a document that is composed of over 200 records. For instance, it is now possible to see that the field h_mag is used much less than the other fields in the near_earth_asteroids.json document.