How to parse JSON array string by using mssql? - json

Question

I've had created the function ParseJson below :
create function ParseJson(
#json nvarchar(max))
returns #tempTable table (topKey nvarchar(max), [Key] nvarchar(max), [Value] nvarchar(max))
as
begin
insert
#tempTable
select
x.[key] topKey
, y.[key]
, y.[value]
from openjson(#json) x
cross apply openjson(x.[value]) y
return
end
-- execute
select * from ParseJson(#json)
I defined a variable #json which is not an array string :
set #json =
N'{
"Chapter":
{
"Section":"1.1"
, "Title":"Hello world."
}
}'
Then I execute the query I will get the result :
If I reset the variable #json which is an array string :
declare #json nvarchar(max)
set #json =
N'{
"Chapter":[
{
"Section":"1.1"
, "Title":"Hello world."
}
,
{
"Section":"1.2"
, "Title":"Be happy."
}
]
}'
Then I execute the query I will get the result :
I hope I can get the result below :
I don't know the result that I expectation is reasonable?
How can I adjust the function to meet the expectation?

Answer 1

If I understand your question correctly, next statement is one possible approach to get your results. It's an example that shows how to get array keys and values (I've added additional Something key). What you need is one additional CROSS APPLY.
DECLARE #json nvarchar(max)
SET #json =
N'{
"Chapter":[
{
"Section":"1.1",
"Title":"Hello world.",
"Something":"Something value"
}
,
{
"Section":"1.2",
"Title":"Be happy."
}
]
}'
SELECT
x.[key] topKey,
z.[key],
z.[value]
FROM OPENJSON(#json) x
CROSS APPLY (SELECT * FROM OPENJSON(x.[value])) y
CROSS APPLY (SELECT * FROM OPENJSON(y.[value])) z
Output:
topKey key value
Chapter Section 1.1
Chapter Title Hello world.
Chapter Something Something value
Chapter Section 1.2
Chapter Title Be happy.
Update:
If your JSON has different types of nested objects, approach will be different:
DECLARE #json nvarchar(max)
set #json = N'{
"Chapter": [
{
"Section":"1.1",
"Title":"Hello world.",
"Something":"Something value"
},
{
"Section":"1.2",
"Title":"Be happy."
}
],
"Author": { "name":"Annie" , "sex":"Female" }
}'
SELECT
x.[key] topKey,
z.[key] [Key],
z.[value] AS [Value]
FROM OPENJSON(#json) x
CROSS APPLY (SELECT * FROM OPENJSON(x.[value])) y
CROSS APPLY (SELECT * FROM OPENJSON(y.[value])) z
WHERE y.[type] = 5
UNION ALL
SELECT
x.[key] topKey,
y.[key] [Key],
y.[value] AS [Value]
FROM OPENJSON(#json) x
CROSS APPLY (SELECT * FROM OPENJSON(x.[value])) y
WHERE y.[type] <> 5
Output:
topKey Key Value
Chapter Section 1.1
Chapter Title Hello world.
Chapter Something Something value
Chapter Section 1.2
Chapter Title Be happy.
Author name Annie
Author sex Female