Extract value from double escaped JSON column in SQL - sql

Question

I have ports_list table with ports column below:
ports
intended_output
"[{\"id\":193,\"name\":\"PORT C\"}]"
PORT C
"[{\"id\":204,\"name\":\"PORT D\"}]"
PORT D
"[{\"id\":45,\"name\":\"PORT I\"},{\"id\":193,\"name\":\"PORT C\"},{\"id\":204,\"name\":\"PORT D\"},{\"id\":271,\"name\":\"PORT G\"}]"
PORT I, PORT C, PORT D, PORT G
I use this method and somehow managed to get result when there is only single port value in a row unfortunately it is unable to cater for multiple port values in a row:
select ports,
REPLACE( substring(ports, CHARINDEX('"name\":\', ports, 1)+10, LEN(ports)-10),
'\"}]"',
''
)
from ports_list
ports
output
"[{\"id\":193,\"name\":\"PORT C\"}]"
PORT C
"[{\"id\":204,\"name\":\"PORT D\"}]"
PORT D
"[{\"id\":45,\"name\":\"PORT I\"},{\"id\":193,\"name\":\"PORT C\"},{\"id\":204,\"name\":\"PORT D\"},{\"id\":271,\"name\":\"PORT G\"}]"
PORT I"},{"id":193,"name":"PORT C"},{"id":204,"name":"PORT D"},{"id":271,"name":"PORT G"}]"
Can someone help me to get the intended output as per the first table?

Answer 1

Your ports column is a double-escaped JSON, in other words, it contains a JSON-escaped string that represents a JSON object.
So we just need to get it back into regular JSON to query it. Let's stuff it into a [] JSON array, then pass it to JSON_VALUE:
select ports,
STRING_AGG(j.name, ', ')
from ports_list
outer apply OPENJSON(JSON_VALUE('[' + ports + ']', '$[0]'))
with (name nvarchar(100) '$.name') as j
group by ports;

Answer 2

You created a soluntion to resolve only when exists one port.
The function CharIndex is returning the first ocorrency of '"name":' always and the function SUBSTRING always return the string minus the ten last characters.
A form to resolve the problem is creating the user function to return all ocorrency of port.
try create the function below
CREATE FUNCTION uf_findPorts
(
#string nvarchar(max)
)
RETURNS nvarchar(MAX)
AS
BEGIN
DECLARE
#length INT ,
#aux INT ,
#return NVARCHAR(MAX)
SET #length = LEN(#string)
SET #aux = 1
SET #return = ''
WHILE(CHARINDEX('"name\":\', #string,#aux) != 0)
BEGIN
SET #return = #return + ' ' + REPLACE( substring(#string,
CHARINDEX('"name\":\', #string,#aux)+10,
6),
'\"}]"',
''
)
SET #string = SUBSTRING(#string,CHARINDEX('"name\":\', #string,#aux) + 6,LEN(#string) )
END
RETURN #return
END
GO
To Test:
select ports,dbo.uf_findPorts(ports)
from ports_list
SELECT dbo.uf_findPorts('[{\"id\":45,\"name\":\"PORT I\"},{\"id\":193,\"name\":\"PORT C\"},{\"id\":204,\"name\":\"PORT D\"},{\"id\":271,\"name\":\"PORT G\"}]')
SELECT dbo.uf_findPorts('"[{\"id\":193,\"name\":\"PORT C\"}]"')
OBS: If exists any error of write you can corret me

Answer 3

Thanks to those who tried to help.
Posting my solution here if anyone stumbled into similar problem in the future:
select ports = replace(replace(replace(dbo.fnRemovePatternFromString(dbo.fnRemovePatternFromString(dbo.fnRemovePatternFromString(dbo.fnRemovePatternFromString(ports,'%[\"{}]%',1),'%name:%',5),'%id:%',3),'%[0-9]%',1),'[,',''),',,',','),']','')
from ports_list