12 October 2021

Everybody needs a break: APEX_WEB_SERVICE #JoelKallmanDay

When Tim Hall announced that there will be a Community blog-day in memory of Joel Kallman, I knew I wanted to participate.
For this post, I'll keep it technical (somewhat).

I'm old enough to remember what a hassle it was to call a webservice from PL/SQL and now appreciate how easy it is. So, this post is about APEX_WEB_SERVICE.
To show how easy it is to work with APEX_WEB_SERVICE and as everybody loves a holiday, I decided to combine the two.
There is a webservice which gives you public holidays (per country) which can be found at: https://date.nager.at/.

For this example I created a table which holds the date and the description of the holiday

  create table my_holidays
   (holiday date
   ,description varchar2(500)
   )
  

And the procedure to populate the table for a given year is as follows:

create or replace
procedure populate_holidays (p_year in number)
is
   --
   l_url      constant varchar2(500) := 'https://date.nager.at/api/v3/publicholidays';
   l_response blob;
   --
begin
   l_response := apex_web_service.make_rest_request_b (p_url         => l_url||'/'||to_char (p_year)||'/NL'
                                                      ,p_http_method => 'GET'
                                                      );
   insert into my_holidays
      (holiday
      ,description
      )
   select dt
         ,name
     from json_table (l_response, '$[*]'
               columns (dt date path '$.date'
                       ,name varchar2(100) path '$.name'
                       ,nested path '$.counties[*]'
                            columns (county path '$')))
   ;
end populate_holidays;

Look at the elegance of the call to APEX_WEB_SERVICE, a very straightforward call to the URL of the Public Holiday API.
An INSERT-SELECT with a JSON_TABLE completes the procedure.

Calling the procedure with

begin
   populate_holidays (p_year => 2022);
end;
/
  
yields the following result:
select *
  from my_holidays
/
01-01-22	New Year's Day
15-04-22	Good Friday
17-04-22	Easter Sunday
18-04-22	Easter Monday
27-04-22	King's Day
05-05-22	Liberation Day
26-05-22	Ascension Day
05-06-22	Pentecost
06-06-22	Whit Monday
25-12-22	Christmas Day
26-12-22	St. Stephen's Day
Never knew that the second day of Christmas (yes, we have that in The Netherlands) is called St. Stephen's Day.

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