Get Children nodes in json string using sql stored procedure? - json

Question

I have a JSON string passed into stored procedure as follows,
{"config": {
"site": "Internal",
"library": "test-library",
"folderHierarchy": {
"name": "folder1",
"children": {
"name": "folder2",
"children": {
"name": "folder3"
}
}
},
"meta_data": [{
"meta_text": "date-created",
"meta_value": "2020-04-17"
}, {
"meta_text": "date-modified",
"meta_value": "2020-04-17"
}]
}}
I need to get folder names inside folderHierarchy node , it can have many number or folders inside as children.
First I tried to get folderHierarchy as a JSON string and iterate through that JSON string.
DECLARE #CONFIG VARCHAR(MAX) = '{"config": {
"site": "Internal",
"library": "test-library",
"folderHierarchy": {
"name": "folder1",
"children": {
"name": "folder2",
"children": {
"name": "folder3"
}
}
},
"meta_data": [{
"meta_text": "date-created",
"meta_value": "2020-04-17"
}, {
"meta_text": "date-modified",
"meta_value": "2020-04-17"
}]
}}'
DECLARE #folderHierarchy VARCHAR(MAX);
SET #folderHierarchy = JSON_QUERY(#CONFIG, '$.config.folderHierarchy');
SELECT #folderHierarchy;
SELECT *
FROM openjson(#folderHierarchy)
WITH(
name VARCHAR(max) '$.name',
childern NVARCHAR(MAX) '$.children' AS JSON
) AS P
OUTER APPLY OPENJSON(P.childern)
WITH (name NVARCHAR(MAX) '$.name');
But this give me the first and second folder names.
Can anyone help me to get all the folder names, the main thing is I haven't control about number of child item in a folder.
I mean folder1 can have folder called folder2, and folder 2 can have folder called folder 3, and folder3 can have folder called folder4 etc.. etc..

Answer 1

You could use a Recursive CTE for this. The default settings on SQL Server will allow you to recurse up to 100 levels deep (see MAXRECUSRION)...
declare #Config nvarchar(max) =
N'{"config": {
"site": "Internal",
"library": "test-library",
"folderHierarchy": {
"name": "folder1",
"children": {
"name": "folder2",
"children": {
"name": "folder3"
}
}
},
"meta_data": [{
"meta_text": "date-created",
"meta_value": "2020-04-17"
}, {
"meta_text": "date-modified",
"meta_value": "2020-04-17"
}]
}}';
with JsonFolders as (
select
1 as level,
name,
children
from openjson(#Config, N'$.config.folderHierarchy') with (
name nvarchar(max) N'$.name',
children nvarchar(max) N'$.children' as json
)
union all
select
1 + level,
Child.name,
Child.children
from JsonFolders JF
cross apply openjson(JF.children) with (
name nvarchar(max) N'$.name',
children nvarchar(max) N'$.children' as json
) Child
)
select * from jsonFolders;