How to generate nested nth level JSON object in T-SQL? - json

Question

I have below data
against below query
declare #t table
(
Id int identity,
name varchar(50),
rootid int,
level int
);
insert into #t(name, rootid, level)
values
('Home', 0, 0)
,('Transaction', 0, 0)
, ('Settings', 0, 0)
,('Purchase Request', 2, 1)
,('Purchase Order', 2, 1)
,('Inventory', 2, 1)
,('Payment Advice', 2, 1)
,('Setup', 3, 1)
,('Budget', 3, 1)
,('CRC', 3, 1)
,('Create PR', 4, 3);
select * from #t;
Desire output:
[{
"Id": 1,
"name": "Home",
"rootid": 0,
"level": 0
}, {
"Id": 2,
"name": "Transaction",
"rootid": 0,
"level": 0,
"children": [{
"Id": 4,
"name": "Purchase Request",
"rootid": 2,
"level": 1,
"children": [{
"Id": 11,
"name": "Create PR",
"rootid": 4,
"level": 3
}]
}, {
"Id": 5,
"name": "Purchase Order",
"rootid": 2,
"level": 1
}, {
"Id": 6,
"name": "Inventory",
"rootid": 2,
"level": 1
}, {
"Id": 7,
"name": "Payment Advice",
"rootid": 2,
"level": 1
}]
}, {
"Id": 3,
"name": "Settings",
"rootid": 0,
"level": 0,
"children": [{
"Id": 8,
"name": "Setup",
"rootid": 3,
"level": 1
}, {
"Id": 9,
"name": "Budget",
"rootid": 3,
"level": 1
}, {
"Id": 10,
"name": "CRC",
"rootid": 3,
"level": 1
}]
}]
Also Tried #Iptr answer:
;WITH result (id, name, rootId, parent, Level) AS
(
SELECT id,
name,
RootId,
Id as Parent,
0 as Level
FROM #t
WHERE RootId= 0
UNION ALL
SELECT t.id,
t.Name,
t.RootId,
r.Parent,
r.Level + 1
FROM #t t
INNER JOIN result r ON r.id = t.RootId
)
SELECT t.*, json_query(nullif(c.children, '[{}]')) as children
FROM #t as t
outer apply (
select
(
select r.*
from result as r
where r.parent = t.Id
and r.level > 0
order by r.id
for json auto
) as children
) as c
where t.level = 0
order by t.Level
for json auto;
Output
[{
"Id": 1,
"name": "Home",
"rootid": 0,
"level": 0
}, {
"Id": 2,
"name": "Transaction",
"rootid": 0,
"level": 0,
"children": [{
"id": 4,
"name": "Purchase Request",
"rootId": 2,
"parent": 2,
"Level": 1
}, {
"id": 5,
"name": "Purchase Order",
"rootId": 2,
"parent": 2,
"Level": 1
}, {
"id": 6,
"name": "Inventory",
"rootId": 2,
"parent": 2,
"Level": 1
}, {
"id": 7,
"name": "Payment Advice",
"rootId": 2,
"parent": 2,
"Level": 1
}, {
"id": 11,
"name": "Create PR",
"rootId": 4,
"parent": 2,
"Level": 2
}]
}, {
"Id": 3,
"name": "Settings",
"rootid": 0,
"level": 0,
"children": [{
"id": 8,
"name": "Setup",
"rootId": 3,
"parent": 3,
"Level": 1
}, {
"id": 9,
"name": "Budget",
"rootId": 3,
"parent": 3,
"Level": 1
}, {
"id": 10,
"name": "CRC",
"rootId": 3,
"parent": 3,
"Level": 1
}]
}]
Above query is not returning nth json child objects, let say if I have nth level of menu items, Parent have multiple Childs and Childs have multiple Childs like treeview.
Tried #Naveen Arora answer:
select ID,name,'' as id,'' as name from Navigations where id not in (select rootid from Navigations) and rootid=0
union
select B.id,B.name,A.id,A.name from Navigations A join Navigations B on A.rootid=B.id
FOR JSON AUTO;
But output
[{
"ID": 1,
"name": "Home",
"id": 0,
"name": ""
}, {
"ID": 2,
"name": "Transaction",
"id": 4,
"name": "Create PR"
}, {
"ID": 2,
"name": "Transaction",
"id": 5,
"name": "Generate PO"
}, {
"ID": 2,
"name": "Transaction",
"id": 6,
"name": "Create Receipt"
}, {
"ID": 2,
"name": "Transaction",
"id": 7,
"name": "Create Issue Request"
}, {
"ID": 2,
"name": "Transaction",
"id": 8,
"name": "Create Issue Note"
}, {
"ID": 2,
"name": "Transaction",
"id": 9,
"name": "Approve Payment Advice"
}, {
"ID": 3,
"name": "Settings",
"id": 11,
"name": "Navigation Management"
}, {
"ID": 11,
"name": "Navigation Management",
"id": 12,
"name": "Navigation & Form Mapping"
}]
Above output it's not include Childs node. Like in Settings I have Navigation Management -> Navigation & Form Mapping

Answer 1

If the sql server version is 2016 or newer than 2016 then you can use FOR JSON PATH.
Assuming that results are stored in test table. This is just to give you an idea how you can do this, may not give you the exact output but you can change it as per your requirement.
SELECT
t.Id AS 'Id',
t.Name AS 'Name',
children = (
SELECT A.id,A.name from test A join test B on A.rootid=B.id
FOR JSON PATH
)
FROM Test t
FOR JSON PATH;
And if it is older than 2016 then you may refer this.

Answer 2

declare #t table
(
Id int identity,
name varchar(50),
rootid int,
level int
);
insert into #t(name, rootid, level)
values
('Home', 0, 0),('Transaction', 0, 0), ('Settings', 0, 0),
('Create PR', 2, 1), ('Generate PO', 2, 1), ('Create Receipt', 2, 1), ('Create Issue Request', 2, 1), ('Create Issue Note', 2, 1), ('Approve Payment Advice', 2, 1),
('Navigation Management', 3, 1), ('Navigation & Form Mapping', 3, 1);
select * from #t;
;WITH result (id, name, rootId, parent, Level) AS
(
SELECT id,
name,
RootId,
Id as Parent,
0 as Level
FROM #t
WHERE RootId= 0
UNION ALL
SELECT t.id,
t.Name,
t.RootId,
r.Parent,
r.Level + 1
FROM #t t
INNER JOIN result r ON r.id = t.RootId
)
SELECT t.*, json_query(nullif(c.children, '[{}]')) as children
FROM #t as t
outer apply (
select
(
select r.*
from result as r
where r.parent = t.Id
and r.level > 0
order by r.id
for json auto
) as children
) as c
where t.level = 0
order by t.Level
for json auto;
SELECT t.*, json_query(nullif(c.children, '[{}]')) as children
FROM #t as t
outer apply (
select
(
select r.*
from #t as r
where r.rootid = t.Id
and r.level > 0
order by r.id
for json auto
) as children
) as c
where t.level = 0
order by t.Level
for json auto;

Answer 3

My apology for late posting my answer. But I really appreciate the efforts of #Iptr and #NaveenArora answer on my post. After I do some brain storming on my case I've finally found the way to do it.
Create this function:
create function [dbo].[fnUDFCreateJSON](#currentId int)
returns varchar(max)
begin
declare #json nvarchar(max)
IF #currentId <> 0
BEGIN
set #json =
(
select [ID], [Name], CSSClass, RouteURL, json_query(dbo.fnUDFCreateJSON([ID])) as SubNavigation
from dbo.Navigations
where RootId = #currentId
for json auto
);
END
ELSE
BEGIN
set #json =
(
select [ID], [Name], CSSClass, RouteURL, '' as SubNavigation from dbo.Navigations where RootId = 0
for json auto
);
END
return #json
end
and call it by using stored procedure:
CREATE PROCEDURE [dbo].[spGetStartupNavigations]
AS
BEGIN
SELECT
(SELECT
ID, Name, CSSClass, RouteURL,
JSON_QUERY (dbo.fnUDFCreateJSON(ID)) AS SubNavigation
FROM
dbo.Navigations
WHERE
RootId = 0
FOR JSON AUTO) AS Navigation
END
That's it.