Nested JSON in MySQL with filtering - mysql

Question

Here's the JSON that I have in the MySQL table:
{
"qmSubsegmentFlags": [
{
"text": "Accuracy",
"id": 1,
"children": [
{
"text": "Mistranslation",
"id": 2,
"children": [
{
"text": "Terminology",
"id": 3
}
]
},
{
"text": "Omission",
"id": 4
},
{
"text": "Addition",
"id": 5
},
{
"text": "Untranslated",
"id": 6
}
]
}
]
}
So you see, id's and text can be in different levels. I only have the value of the id and have to get the text for this with SQL. Below a JSON path that works for the first level, but not for all levels. Neither does it work in MySQL, since MySQL only supports limited filtering.
$.qmSubsegmentFlags[?(#.id==1)].text
A little SQL that goes into the right direction, but also does not solve the issue.
SELECT JSON_EXTRACT(t.qmSubsegmentFlags, '$.qmSubsegmentFlags[*].text') AS lqa FROM translate5.LEK_task AS t where id = 3719;
I used to be a programmer, but after 4 years of project management, my skills are dead. But I need a proof of concept until monday. Any help would be great!

Answer 1

Here's a solution tested on MySQL 8.0.32.
WITH RECURSIVE tree AS (
SELECT j.id, j.text, j.children
FROM LEK_task CROSS JOIN JSON_TABLE(
JSON_EXTRACT(qmSubsegmentFlags, '$.qmSubsegmentFlags'),
'$[*]' COLUMNS (
text TEXT PATH '$.text',
id INT PATH '$.id',
children JSON PATH '$.children'
)
) AS j
WHERE LEK_task.id = 3719
UNION ALL
SELECT j.id, j.text, j.children
FROM tree CROSS JOIN JSON_TABLE(
children,
'$[*]' COLUMNS(
text TEXT PATH '$.text',
id INT PATH '$.id',
children JSON PATH '$.children'
)
) AS j
)
SELECT id, text FROM tree;
Result:
+------+----------------+
| id | text |
+------+----------------+
| 1 | Accuracy |
| 2 | Mistranslation |
| 4 | Omission |
| 5 | Addition |
| 6 | Untranslated |
| 3 | Terminology |
+------+----------------+
You can add a WHERE id = 1 to the last line of the query to get the row for a specific id.