XML parse issue from a json field - snowflake-cloud-data-platform

Question

I have a json column with an XML field I am trying to parse
{
"guid": "ba410633-d191-deab-fe63-23f732c517aa",
"id": 1847510,
"request":<?xml version='1.0' encoding='UTF-8'?><ConnectRequest xmlns='http://www.acme.com/NetConnect' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://www.acme.com/API'><EAI>QWE</EAI><DBHost>TEST</DBHost><ReferenceId>aa</ReferenceId><Request xmlns='http://www.acme.com' version='1.0'><Products><PreciseIDServer><XMLVersion>5.0</XMLVersion><Subscriber><Preamble>ABC</Preamble><OpInitials>BCD</OpInitials><SubCode>2436170</SubCode></Subscriber></PreciseIDServer></Products></Request></ConnectRequest>"
}
XML field is like this
<?xml version='1.0' encoding='UTF-8'?>
<ConnectRequest xmlns='http://www.acme.com/NetConnect' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://www.acme.com/API'>
<EAI>QWE</EAI>
<DBHost>TEST</DBHost>
<ReferenceId>aa</ReferenceId>
<Request xmlns='http://www.acme.com' version='1.0'>
<Products>
<PreciseIDServer>
<XMLVersion>5.0</XMLVersion>
<Subscriber>
<Preamble>ABC</Preamble>
<OpInitials>BCD</OpInitials>
<SubCode>2436170</SubCode>
</Subscriber>
</PreciseIDServer>
</Products>
</Request>
</ConnectRequest>
I have tried the following but no luck, it returns null all the time
select xmlget(request, 'DBHost'):"$" as DBHost
from (select json_field:request::variant request from table)
Is it a datatype issue? I was able to parse another column from a table which has a variant column with xml data using the same xmlget.

Answer 1

with
XML(DBHOST, PRODUCTS, PRECISEIDSERVER, SUBCODE) as
(
select get(xmlget(parse_xml(json_field:request::string), 'DBHost'), '$')::string as DBHOST,
get(xmlget(parse_xml(json_field:request::string), 'Request'), '$')::string as PRODUCTS,
get(xmlget(parse_xml(PRODUCTS::string), 'PreciseIDServer'), '$')::string as PreciseIDServer,
get(xmlget(parse_json(PreciseIDServer)[1], 'SubCode'), '$')::int as SourceCode
from MY_TABLE
)
select DBHOST, SUBCODE from XML;
XMLGET would work that way on a variant column that contains only XML. In this case, the XML is not the variant. The JSON is the variant and the XML is one of the properties. It needs to be treated as a string property, and then manipulated as XML. To do that you need to convert it from a JSON property using ::string. You then need to use PARSE_XML to convert the string into a variant. Finally, you can use xmlget on the variant resulting from PARSE_XML and use GET with the final parameter of $ to indicate that you just want the value, not the begin and end tags too. The final ::string converts that final result into a string so that it doesn't get wrapped in double quotes.
One note - there's a missing close tag in the sample xml that fails when using the PARSE_XML function. I added the close tag for testing. The XML must be valid in order to convert from a string to an XML variant.
Edit: Updated to a CTE to add parsing for SubCode. To get at an XML node that's nested a few layers deep, a good approach is taking it step by step in columns with a CTE to select only the ones you want.