JSON output format from SQL Server - json

Question

I posted a question about this yesterday, which was very helpfully answered by solutionist, but I now have a follow up question along the same lines.
I want to get two sets of data out from the JSON.
I have three data sets, one is the header, one is a set of customer records and the last is an error object.
The structure I am looking to try and get is:
Header
Customers
Error
but what I'm getting is:
Header
Customer, Error
Customer, Error
Now in this example, the error is null so I'm happy either with the error being omitted because it's null, or coming back as an empty object, but I want a single one, not one per customer.
This is what I currently get:
select isjson('{"APIResult":[{"ID":200,
"Status_Message":"Success",
"Developer_Message":"Customers found",
"User_Message":"Customers found",
"Return_Code":0,
"Customer":[{"ID":"A6B10FA0-85AD-422D-8A7E-07EEA541593E",
"First_Name":"Bbb",
"Paternal_Last_Name":"Bbbbb",
"Email_Address":"bbbb#example.com",
"Error":[{}]
},
{"ID":"91EE2FD6-2C40-4CFD-ABB7-2CDAE3624487",
"First_Name":"Aaaa",
"Paternal_Last_Name":"Aaaaa",
"Email_Address":"aaaaa#example.com",
"Error":[{}]
}]
}]
}')
And this is what I am trying to get:
select isjson('{"APIResult":[{"ID":200,
"Status_Message":"Success",
"Developer_Message":"Customers found",
"User_Message":"Customers found",
"Return_Code":0,
"Customer":[{"ID":"A6B10FA0-85AD-422D-8A7E-07EEA541593E",
"First_Name":"Bbb",
"Paternal_Last_Name":"Bbbbb",
"Email_Address":"bbbb#example.com"
},
{"ID":"91EE2FD6-2C40-4CFD-ABB7-2CDAE3624487",
"First_Name":"Aaaa",
"Paternal_Last_Name":"Aaaaa",
"Email_Address":"aaaaa#example.com"
}],
"Error":[{}]
}]
}')
Both are valid JSON (I have tested this this time, as you can see), but I can't work out how to get the second format.
This is the query I am running to get the output:
declare #returncode int = 0
,#VerboseMsg nvarchar(4000) = 'Customers found'
,#DisplayMsg nvarchar(4000) = 'Customers found'
CREATE TABLE #Customers (CustomerID UNIQUEIDENTIFIER DEFAULT(NEWID()), FirstName NVARCHAR(50), PaternalLastName NVARCHAR(50), EmailAddress NVARCHAR(250))
INSERT INTO #Customers (FirstName, PaternalLastName, EmailAddress)
VALUES ('Aaaa', 'Aaaa', 'aaaa#example.com'), ('Bbbb', 'Bbbb', 'bbbb#example.com')
SELECT st.APIStatus AS 'ID'
,st.StatusMessage AS 'Status_Message'
,#VerboseMsg AS 'Developer_Message'
,#DisplayMsg AS 'User_Message'
,st.ReturnCode AS 'Return_Code'
,[Customer].CustomerID AS 'ID'
,[Customer].FirstName AS 'First_Name'
,[Customer].PaternalLastName AS 'Paternal_Last_Name'
,[Customer].EmailAddress AS 'Email_Address'
,[Error].ErrorCode AS 'Error_Code'
,[Error].ErrorMsg AS 'Error_Message'
FROM (SELECT 200 AS APIStatus, 'Success' AS StatusMessage, #ReturnCode AS ReturnCode) st
LEFT JOIN (SELECT CustomerID
,FirstName
,PaternalLastName
,EmailAddress
,#ReturnCode AS ReturnCode
FROM #Customers
) As [Customer]
ON st.ReturnCode = [Customer].ReturnCode
LEFT JOIN (SELECT #ReturnCode AS ErrorCode, #DisplayMsg AS ErrorMsg WHERE #returncode != 0) AS [Error]
ON [Error].ErrorCode = st.ReturnCode
FOR JSON AUTO, ROOT('APIResult')
Is it the case that the only way I can get this output is by stitching things together myself? JSON is still quite new to me, and I am struggling to get to grips with the makeup of it.

Answer 1

In this setup I would place error code after return code and would use subqueries with JSON PATH like this:
SELECT st.APIStatus AS 'ID'
,st.StatusMessage AS 'Status_Message'
,#VerboseMsg AS 'Developer_Message'
,#DisplayMsg AS 'User_Message'
,st.ReturnCode AS 'Return_Code'
, (SELECT #ReturnCode AS ErrorCode, #DisplayMsg AS ErrorMsg FOR JSON PATH) AS [Error]
,[Customer].CustomerID AS 'ID'
,[Customer].FirstName AS 'First_Name'
,[Customer].PaternalLastName AS 'Paternal_Last_Name'
,[Customer].EmailAddress AS 'Email_Address'
FROM (SELECT 200 AS APIStatus, 'Success' AS StatusMessage, #ReturnCode AS ReturnCode) st
LEFT JOIN (SELECT CustomerID
,FirstName
,PaternalLastName
,EmailAddress
,#ReturnCode AS ReturnCode
FROM #Customers
) As [Customer]
ON st.ReturnCode = [Customer].ReturnCode -- why?
FOR JSON AUTO, ROOT('APIResult')
Note that if you don't have any record in Error it will be omitted, but you can use null for that case, also I have noticed that you used #ReturnCode twice and I don;t know if that is intentionally or mistake.