Re: json_table(httpgetclob, nested array

Yea - Peter figured it out but didn't know what lax was. I just pointed out the documentation. I looked at the SQL json handling myself, but ended up dropping back to python. It confused me also.

-----Original Message-----
From: WEB400 [mailto:web400-bounces@xxxxxxxxxxxxxxxxxx] On Behalf Of Jon Paris
Sent: Friday, November 15, 2019 2:09 PM
To: Web Enabling the IBM i (AS/400 and iSeries) <web400@xxxxxxxxxxxxxxxxxx>
Subject: Re: [WEB400] json_table(httpgetclob, nested array

Hmmm - did I thank the wrong person - apologies if I did.

On Nov 15, 2019, at 2:18 PM, Peter Dow <petercdow@xxxxxxxxx> wrote:

Following Booth's idea of keeping my grey cells exercised, I gave this
a try. First, I had to rearrange it so I could copy paste to the
green screen (all I have available for this) and tried

SELECT * FROM json_table('
{
"wData_length":14,
"SeasOceans":[
"Adriatic Sea",
"Arctic Ocean",
"Atlantic Ocean",
"Bay of Bengal",
"Caribbean Sea"
]
}',
'$.SeasOceans[*]'
COLUMNS( SeasOceans varchar(40) )
) as jt

That got me

....+....1....+....2....+....3....+....4
SEASOCEANS
-
-
-
-
-
******** End of data ********

Which looks like it got the 5 elements of the array, but they were
null. Time to rtfm, which says in part

1. The JSON_TABLE function consists of three parts.
2. 1. The JSON object to be deconstructed.
3. 2. A path expression that generates zero or more rows from the JSON
object.
4. 3. The definition of the result columns to be returned. This
includes the column name, the result data type, and a path
expression to use to locate the column information.

Following their example, and trying a few variations, I came up with this:


SELECT * FROM json_table('
{
"wData_length":14,
"SeasOceans":[
"Adriatic Sea",
"Arctic Ocean",
"Atlantic Ocean",
"Bay of Bengal",
"Caribbean Sea"
]
}',
'lax $'
COLUMNS(
wData_length dec(3,0) PATH 'lax $.wData_length', SeasOceans
varchar(40) PATH 'lax $.SeasOceans[1]'
) as jt

which resulted in

....+....1....+....2....+....3....+....4....+....5....
WDATA_LENGTH SEASOCEANS
14 Arctic Ocean
******** End of data ********


The documentation I was reading at
https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_73/sqlp/rbafy
jsontable.htm

did not have an explanation of the "path". Reading further, I found
where it had example of an array within the json object. That got me
to

SELECT * FROM json_table('
{
"wData_length":14,
"SeasOceans":[
"Adriatic Sea",
"Arctic Ocean",
"Atlantic Ocean",
"Bay of Bengal",
"Caribbean Sea"
]
}',
'lax $.SeasOceans[*]'
COLUMNS(
SeasOceans varchar(40) PATH 'lax $')
) as jt

which returns

....+....1....+....2....+....3....+....4
SEASOCEANS
Adriatic Sea
Arctic Ocean
Atlantic Ocean
Bay of Bengal
Caribbean Sea
******** End of data ********

I still have no idea what the lax in the path means. I tried changing it to abc and it didn't complain, but it didn't select anything either.

--
*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
petercdow@xxxxxxxxx <mailto:petercdow@xxxxxxxxx> pdow@xxxxxxxxxxxxxx
<mailto:pdow@xxxxxxxxxxxxxx> /

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