The document discusses various methods for generating JSON from SQL queries in Oracle APEX applications. It compares manually concatenating strings, using the apex_util.json_from_* procedures, the PL/JSON library, the APEX_JSON API package, and Oracle REST Data Services (ORDS). The APEX_JSON package is recommended for most cases as it supports generation and parsing, can be used standalone, has a light footprint, and makes conversion from XML easy. Using a templating engine like Handlebars.js with JSON is also presented as a way to dynamically render HTML from database queries.

2. Speed Up Your APEX Apps with JSON
and Handlebars
Marko Gorički
BiLog

3. About BiLog
• small IT company focused on consulting and business solution development
(using Oracle technologies)
• big APEX company ≈ 25 APEX developers
• our APEX products:
HRMb - HR management software
www.bilog.hr

4. About Me
• started with Oracle Forms and Reports
• working 8 years with APEX
• APEX related blog - apexbyg.blogspot.com
• @mgoricki

5. It depends
There are only five questions about the database:
• The answer to the first three questions is “use bind variables.”
• The answer to the fourth question is “do not use bind variables.”
• The answer to the fifth question is “it depends”.
If you know those answers, you can answer any question about the database!
– Tom Kyte
• In APEX: “it depends”

6. Content

8. JSON
• JavaScript Object Notation – lightweight data interchange format that consists
of name-value pairs
• key features:
• easy to read and write
• easy to generate and parse
• language independent
• subset of JavaScript notation

9. JSON format
• {“name”: value, “name”: value…}
• key elements
• Name
• Value
• Object (unordered collection)
• Array (ordered collection)
Name/key/attribute
Value
Object
Array

10. Value
• string - double quotes(“”), backslash escapes ()
• number - decimal notation (possibly signed and possibly including a decimal
exponent)
• no date data type
• null different to SQL null

11. Object
• unordered set of name/value pairs
• begins and ends with brace - {…}
• name/string/attribute/key followed by colon
• separated by comma

12. Array
• ordered collection of values
• begins and ends with brackets - […]
• separated by comma

13. *Please, don’t use this in your CV !! 

14. JSON vs XML
JSON XML
Predefined data types
Typless or based on XML Schema or document type
definition (DTD)
Structured data Structured and semi-structured data
Data-centric Data or document-centric
Data representation language Document markup and data representation language

16. Generate JSON
• prior to APEX 5:
• by manually concatenating strings
• apex_util.json_from_*
• PL/JSON

17. Generate JSON
• with APEX 5 - APEX_JSON API package

18. Generate JSON
• Other solutions
• Oracle REST Data Services (ORDS)
• node.js

19. SQL source
• why short column alias (x, a, b and c)?
• JSON size:
• 500 rows - 29.1KB vs 43.3KB
• less readable vs ≈30% smaller size

20. SQL source
With short aliasWithout alias

21. Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

22. Manually by concatenating
strings
• using sys.htp package
• CONS:
• hard to maintain and develop
• manually escape values
• manually define value types
• easy to make mistakes
• no parsing
• PROS
• customizable
• it can be fast

23. Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

24. Using apex_util.json_from*
• procedures: *_sql, *_array, *_items, *_string
• CONS:
• “not documented”
• no null, true and false values
• hard to create nested JSON objects
• no parsing
• security issue: passing string into json_from_sql
• PROS:
• simple and easy to develop
• auto escaping
• recognizes some value types (number)
• available before APEX 5

25. Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

26. PL/JSON
• open source library (2009.)
• DB types: JSON (object) and JSON_LIST (array)
• CONS
• complex
• lack of real documentation
• performance issues
• PROS
• can be stored in DB
• parsing
• supports all value types
• open source
• available before APEX 5

27. Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

28. APEX_JSON API
• PROS:
• native
• generating and parsing
• can be used as standalone (CLOB)
• light footprint
• easy conversion from/to xmltype
• CONS:
• only in APEX 5.0+

29. APEX_JSON API
• Simple JSON Array
apex_json.open_array;
for emp in (select *
from emp
where deptno = p_deptno)
loop
apex_json.write(emp.ename);
end loop;
apex_json.close_array;

30. Nested JSON object - with cursor
declare
cur_dept sys_refcursor;
begin
open cur_dept for
select d.dname
, d.loc
, cursor (select e.ename
, e.job
, e.sal
, (select m.ename from emp m where m.empno = e.mgr) manager
, decode(e.comm, null, 'false', 'true') as hasCommision
from emp e
where d.deptno = e.deptno) as emps
from dept d
where d.deptno = nvl(p_deptno, d.deptno);
apex_json.open_object;
apex_json.write('DEPTS',cur_dept);
apex_json.close_object;
end;

32. Parsing simple JSON object
declare
v_json_object varchar2(100) := '{"dname":"ACCOUNTING","loc":"NEW YORK"}';
begin
apex_json.parse(v_json_object);
dbms_output.put_line(
apex_json.get_varchar2('dname')
);
end;

33. Parsing nested JSON object
declare
v_json_object clob := ‘{…}’;
begin
apex_json.parse(v_json_object);
dbms_output.put_line(
apex_json.get_varchar2('DEPTS[1].EMPS[2].ENAME')
);
dbms_output.put_line(
apex_json.get_varchar2(p_path => 'DEPTS[%d].EMPS[%d].ENAME’
, p0 => 1
, p1 => 2)
);
end;

34. Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

35. Oracle REST Data Services (ORDS)
• easy to develop modern REST interfaces
• ways to use it:
• APEX GUI
• SQL Developer (auto-rest)
• PL/SQL API
• Simple Oracle Document Access (SODA) API over REST
• URL format:
• protocol://host:port/ords-name/apex-workspace-name/uri-template/bind-value
• https://apex.oracle.com/pls/apex/mgoricki/dept/10

36. ORDS Demo

37. Oracle Rest Data Services (ORDS)
• CONS
• little slower
• you need ORDS
• PROS
• declarative and simple
• many options
• easy to create nested JSON objects

38. Best method?
• It depends! 

39. 657.80
1574.00
287.00
332.80
254.70
0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00 1800.00
ORDS
PL/JSON
apex_json
apex_util.json_from_sql
Manually
Average execution time (ms)

40. 29.90
29.30
29.30
29.30
29.30
29.00 29.10 29.20 29.30 29.40 29.50 29.60 29.70 29.80 29.90 30.00
ORDS
PL/JSON
apex_json
apex_util.json_from_sql
Manually
Average JSON size (KB)

42. JSON and Oracle12c
• native support from 12.1.0.2
• store JSON data (with VARCHAR2, CLOB or BLOB data types), index,
query…
• parse JSON data with SQL

43. JSON and Oracle12c
• storing JSON data
create table my_json(
json_col clob
);
alter table my_json add constraint valid_json
check (json_col is json);
insert into my_json
values ('{"dname":"ACCOUNTING","loc":"NEW YORK"}');

44. JSON and Oracle12c
• parsing JSON data
SQL> select json.json_col.dname from my_json json;
DNAME
---------
ACCOUNTING

45. Using JSON
• APEX use it (IR, Page designer)
• New APEX 5.1 grid
• Oracle JET
• fetch asynchronously data with AJAX
• communicate with Web services (REST API - Twitter, Flickr, Google
Apps)
• easy to use with JavaScript

47. Old HTML way
HTTP Request
HTML page
Client / Browser Server / DB

48. AJAX partial page
AJAX Request
HTML part
Client / Browser Server / DB

49. Client side templates
AJAX Request
JSON
HTML Template
Client / Browser Server / DB

50. • light weighted JavaScript templating engine (Mustache.js,
AngularJS, Backbone.js, Ember.js, Marko.js…) used for client-side
data binding
• subset of Mustache.js + minimal logic
• works by expanding tags in a template using values provided by
JSON object
• tags can be replaced with value, nothing or series of values
Handlebars.js

51. Handlebars.js
Example

52. Handlebars.js templates
• tags start and end with double braces (mustaches) {{…}}
• two simple types of tags:
• variables - basic tag type
{{title}}
• sections/block expressions - render block of text one or more times
{{#posts}}…{{/posts}}

55. In APEX
• Add JS library
• Create template item

56. • Define HTML object where to put result
• Fetch JSON and run render function
In APEX
Example

57. Classic report example

58. 578.80
657.80
1574.00
287.00
332.80
254.70
0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00 1800.00
Report region
ORDS
PL/JSON
apex_json
apex_util.json_from_sql
Manually
Average execution time (ms)

59. 122.00
29.90
29.30
29.30
29.30
29.30
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00
Report region
ORDS
PL/JSON
apex_json
apex_util.json_from_sql
Manually
Average JSON size (KB)

60. Real-life example
Generation time: 2 minutes
Response time: 2.3 MB
Only first 700 rows

61. Real-life example
Generation time: 2.9s vs 2 minutes
Response time: 500KB vs 2.3 MB
All 2422 rows vs 700 rows

62. Q&A