til/mysql/get-idea-of-what-is-in-a-json-column.md

Get Idea Of What Is In A JSON Column

While digging through some data trying to reacquaint myself with the overall schema and data model, I ran into an issue selecting rows from this content_resource table. There was so much text packed in to the "body", "summary", and "description" key-value pairs of fields JSON column that a simple select * ... limit 3; was overwhelming the screen with text and table formatting characters (i.e. +------+-------).

I figured the fields JSON followed a reliable structure, at least for records of the same type. So, let's start by only grabbing the json_keys so that I can get a sense of the shape of the JSON.

select id, json_keys(fields)
from content_resource
where type = 'post'
limit 3;

+-----+-----------------------------------------------------------------------------------------------------------+
| id  | json_keys(`fields`)                                                                                       |
+-----+-----------------------------------------------------------------------------------------------------------+
|  1  | ["body", "slug", "state", "title", "summary", "postType", "visibility", "description", "originalLessonId"] |
|  2  | ["body", "slug", "state", "title", "summary", "postType", "visibility", "description", "originalLessonId"] |
|  3  | ["body", "slug", "state", "title", "summary", "postType", "visibility", "description", "originalLessonId"] |
+-----+-----------------------------------------------------------------------------------------------------------+

For the post type, I see the same keys for this sampling of rows. Now I have an idea what keys are present and can start digging in further.

My next query might look something like this:

select id, fields->'$.slug', fields->'$.title', fields->'$.state'
from content_resource
where type = 'post'
limit 3;