Jeff Kemp

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Oracle Database: Get it Right
Updated: 4 hours 34 min ago

IRs with Subscriptions that might not work

Thu, 2017-02-23 20:31

If you have an Interactive Report with the Subscription feature enabled, users can “subscribe” to the report, getting a daily email with the results of the report. Unfortunately, however, this feature doesn’t work as expected if it relies on session state – e.g. if the query uses bind variables based on page items to filter the records. In this case, the subscription will run the query with a default session state – Apex doesn’t remember what the page item values were when the user subscribed to the report.

This is a query I used to quickly pick out all the Interactive Reports that have the Subscription feature enabled but which might rely on session state to work – i.e. it relies on items submitted from the page, refers to a bind variable or to a system context:

select workspace, application_id, application_name,
page_id, region_name, page_items_to_submit
from apex_application_page_ir
where show_notify = 'Yes'
and (page_items_to_submit is not null
or regexp_like(sql_query,':[A-Z]','i')
or regexp_like(sql_query,'SYS_CONTEXT','i')

For these reports, I reviewed them and where appropriate, turned off the Subscription feature. Note that this query is not perfect and might give some false positives and negatives.

Filed under: Oracle

Quick Pick in Apex Report

Mon, 2017-01-30 02:08

I have an Interactive Report that includes some editable columns, and the users wanted to include some “quick picks” on these columns to make it easy to copy data from a previous period. The user can choose to type in a new value, or click the “quick pick” to quickly data-enter the suggested value.


Normally, a simple page item can have a quick pick by setting the Show Quick Picks attribute on the item. This is not, however, available as an option when generating Apex items in a report.

To do this, I added code like the following to my report query:

         ,p_rows => 1
         ,p_cols => 30
         ,p_item_id => 'f05_'||to_char(rownum,'fm00000'))
       || case when x.prev_ytd_comments is not null
          then '<a href="javascript:$(''#'
            || 'f05_' || to_char(rownum,'fm00000')
            || ''').val('
            || apex_escape.js_literal(x.prev_ytd_comments)
            || ').trigger(''change'')">'
            || apex_escape.html(x.prev_ytd_comments)
            || '</a>'
       as edit_ytd_comments
FROM my_report_view x;

This results in the following HTML code being generated:


In the report definition, the EDIT_YTD_COMMENTS column has Escape Special Characters set to No. This runs a real risk of adding a XSS attack vector to your application, so be very careful to escape any user-entered data (such as prev_ytd_comments in the example above) before allowing it to be included. In this case, the user-entered data is rendered as the link text (so is escaped using APEX_ESCAPE.html) and also within some javascript (so is escaped using APEX_ESCAPE.js_literal).

So, if the data includes any characters that conflict with html or javascript, it is neatly escaped:


And it is shown on screen as expected, and clicking the link copies the data correctly into the item:


This technique should, of course, work with most of the different item types you can generate with APEX_ITEM.

Recommended further reading:

Filed under: APEX Tagged: apex-5.0, javascript, tips-&-tricks

Powerless Javascript

Thu, 2017-01-19 19:37

I was writing a small javascript function, part of which needed to evaluate 10 to the power of a parameter – I couldn’t remember what the exponentiation operator is in javascript so as usually I hit F12 and typed the following into the console:



Wrote and tested the code, checked in to source control. Job done.

A few days later we deployed a new release that included dozens of bug fixes into UAT for testing. Soon after a tester showed me a screen where a lot of stuff wasn’t looking right, and things that had been working for a long time was not working at all.

Developer: “It works fine on my machine.”

After some playing around on their browser I noted that it seemed half of the javascript code I’d written was not running at all. A look at their browser console revealed two things:

  1. they are using Internet Explorer 11
  2. a compilation error was accusing the line with the ** operator

The error meant that all javascript following that point in the file was never executed, causing the strange behaviour experienced by the testers.

A bit of googling revealed that the ** operator was only added to javascript relatively recently and was supported by Chrome 52 and Edge browser but not IE. So I quickly rewrote it to use Math.pow(n,m) and applied a quick patch to UAT to get things back on track.

I think there’s a lesson there somewhere. Probably, the lesson is something like “if you try drive-by javascript coding, you’re gonna have a bad time.”

Filed under: APEX Tagged: exponentiation, javascript, lesson-learned

Target=_Blank for Cards report template

Sat, 2016-12-24 02:20

cardsreport.PNGI wanted to use the “Cards” report template for a small report which lists file attachments. When the user clicks on one of the cards, the file should download and open in a new tab/window. Unfortunately, the Cards report template does not include a placeholder for extra attributes for the anchor tag, so it won’t let me add “target=_blank” like I would normally.

One solution is to edit the Cards template to add the extra placeholder; however, this means breaking the subscription from the universal theme.

As a workaround for this I’ve added a small bit of javascript to add the attribute after page load, and whenever the region is refreshed.

  • Set report static ID, e.g. “mycardsreport”
  • Add Dynamic Action:
    • Event = After Refresh
    • Selection Type = Region
    • Region = (the region)
  • Add True Action: Execute JavaScript Code
    • Code = $("#mycardsreport a.t-Card-wrap").attr("target","_blank"); (replace the report static ID in the selector)
    • Fire On Page Load = Yes

Note: this code affects all cards in the chosen report.

Filed under: APEX Tagged: APEX, javascript, jQuery, tips-&-tricks

Report Link: Save before Navigation

Sun, 2016-10-30 23:46

“We always click ‘Apply Changes’, then we click the button we actually wanted” – a user

Typically an Apex report with an “Open” or “Edit” icon will simply do an immediate navigation to the target page, passing the ID of the record to edit. When the user clicks this link, the page is not submitted and the user is instead redirected.

It’s easy to quickly build large and complex applications in Apex but it’s also very easy to build something that confuses and disorients your users. They only need one instance when something doesn’t work how they expected it to, and they will lose trust in your application.

For example: if most buttons save their changes, but one button doesn’t, they might not notice straight away, and then wonder what happened to their work. If you’re lucky, they will raise a defect notice and you can fix it. More likely (and worse), they’ll decide it’s their fault, and begrudgingly accept slow and unnecessary extra steps as part of the process.

You can improve this situation by taking care to ensure that everything works the way your users expect. For most buttons in an Apex page, this is easy and straightforward: just make sure the buttons submit the page. The only buttons that should do a redirect are those that a user should expect will NOT save the changes – e.g. a “Cancel” button.

For the example of an icon in a report region, it’s not so straightforward. The page might include some editable items (e.g. a page for editing a “header” record) – and if the user doesn’t Save their changes before clicking the report link their changes will be lost on navigation.

To solve this problem you can make the edit links first submit the page before navigating. The way I do this is as follows (in this example, the report query is on the “emp” table:

    1. Add a hidden item P1_EDIT_ID to the page
      • Set Value Protected to No
    2. Add something like this to the report query (without the newlines):
         set:{''P1_EDIT_ID'':''' || emp.rec_id || '''}
        })' AS edit_link
      • Set this new column to Hidden Column
    3. Modify the edit link Target:
      • Type = URL
      • URL = #EDIT_LINK#
    4. Add a Branch at point “After Processing”
      • Set the Target to the page to navigate to
      • Set the item for the record ID to &P1_EDIT_ID.
      • Set the Condition to the following PL/SQL Expression:
      • Make sure the branch is evaluated before any other branches (at least, any others that might respond to this request)
    5. Modify any existing Processing so that the request SAVE_EDIT_ROW will cause any changes on the page to be saved.

You can, of course, choose different item names and request names if needed (just update it in the code you entered earlier). For example, to make it work with the default Apex DML process you might need to use a request like “APPLY_CHANGES_EDIT_ROW”.

Now, when the user makes some changes to the form, then clicks one of the record Edit links, the page will first be submitted before navigating to the child row.

Adding buttons to Apex pages is easy. Making sure every last one of them does exactly what the user expects, nothing more, and nothing less, is the tricky part!

Filed under: Oracle Tagged: tips-&-tricks

Enhancement Request for SQL Developer for users of Logger

Mon, 2016-10-24 07:57

Juergen Schuster, who has been enthusiastically trying OraOpenSource Logger, raised an idea for the debug/instrumentation library requesting the addition of a standard synonym “l” for the package. The motive behind this request was to allow our PL/SQL code to remain easy to read, in spite of all the calls to logger sprinkled throughout that are needed for effective debugging and instrumentation.

In the judgement of some (myself included) the addition of the synonym to the standard package would run the risk of causing clashes on some people’s systems; and ensuring that Logger is installable on all systems “out of the box” should, I think, take precedence.

However, the readability of code is still an issue; so it was with that in mind that I suggested that perhaps an enhancement of our favourite development IDE would go a long way to improving the situation.

Therefore, I have raised the following enhancement request at the SQL Developer Exchange:

Logger: show/hide or dim (highlight) debug/instrumentation code

“The oracle open source Logger instrumentation library is gaining popularity and it would be great to build some specific support for it into SQL Developer, whether as a plugin or builtin. To enhance code readability, it would be helpful for PL/SQL developers to be able to hide/show, or dim (e.g. grey highlight) any code calling their preferred debug/instrumentation library (e.g. Logger).

“One way I expect this might work is that the Code Editor would be given a configurable list of oracle object identifiers (e.g. “logger”, “logger_logs”); any PL/SQL declarations or lines of code containing references to these objects would be greyed out, or be able to be rolled up (with something like the +/- gutter buttons).”

Mockup #1 (alternative syntax highlighting option):


Mockup #2 (identifier slugs in header bar to show/hide, with icons in the gutter showing where lines have been hidden):


“Gold-plated” Option: add an option to the SQL Editor’s right-click context menu – on any identifier, select “Hide all lines with reference to this” and it adds the identifier to the list of things that are hidden!

If you like the idea (or at least agree with the motive behind it) please vote for it.

Filed under: Tools Tagged: enhancement, Logger, oracle-sql-developer

Restriction when column default is sequence.nextval

Mon, 2016-10-03 04:39

Oracle 12c introduced the ability to specify sequence.nextval as the default on a column, which is really nice – including the fact that it eliminates one of your excuses why you don’t decommission those old triggers.

Unfortunately it doesn’t work as you might expect if you use an INSERT ALL statement; it evaluates the default expression once per statement, instead of once per row.

Test case:

create sequence test_seq;

create table test_tab
( id number default test_seq.nextval primary key
, dummy varchar2(100) not null );

insert into test_tab (dummy) values ('xyz');

1 row inserted.

insert all
into test_tab (dummy) values ('abc')
into test_tab (dummy) values ('def')
select null from dual;

Error report -
SQL Error: ORA-00001: unique constraint
(SCOTT.SYS_C00123456) violated

A minor issue, usually, but something to be aware of – especially if you’re not in the habit of declaring your unique constraints to the database!

create sequence test_seq;

create table test_stupid_tab
( id number default test_seq.nextval
, dummy varchar2(100) not null );

insert into test_tab (dummy) values ('xyz');

1 row inserted.

insert all
into test_tab (dummy) values ('abc')
into test_tab (dummy) values ('def')
select null from dual;

2 rows inserted.

select * from test_tab;

i dummy
= =====
1 xyz
2 abc
2 def

Filed under: Oracle Tagged: gotcha, oracle12c, SQL

Must See: AUSOUG Connect 2016 Perth

Tue, 2016-09-06 00:49


If you can get yourself to Perth in November, you must try to get to AUSOUG Connect. Here is my “Must See” list based on the current program (subject to change):

Monday 7 Nov

Tuesday 8 Nov

Lots of Apex goodies, a new (to me, at least) database IDE, plus plenty of solid Oracle database content – there’ll probably be a few conflicts leading to some decisions to make on the day.

I’m looking forward to a long-awaited return of the AUSOUG conference series – I hope to see you all there.

Filed under: AUSOUG Tagged: AUSOUG

Send SMS, MMS and Voice messages from Oracle PL/SQL

Wed, 2016-08-17 02:31

testing receipt of sms and mms

If you need to send almost any message to almost any phone from your Oracle database, and you want to use straight PL/SQL, you may want to consider using my Clicksend API.

  • SMS (Short Message Service)
  • MMS (Multimedia Message Service)
  • Text to Voice

I have released the first beta version of my Oracle PL/SQL API for Clicksend. Read the installation instructions, API reference and download the release from here:

Sending an SMS is as simple as adding this anywhere in your code:

    (p_sender  => 'Mr Tester'
    ,p_mobile  => '+61411111111'
    ,p_message => 'Hi, message sent at '
     || to_char(systimestamp,'DD/MM/YYYY HH24:MI:SS.FF')

All you need to do is signup for a Clicksend account. You’ll only be charged for messages actually sent, but they do require you to pay in advance – e.g. $20 gets you about 300 messages (Australian numbers). You can get test settings so that you can try it out for free.

I’ve been using Clicksend for years now, and have been satisfied with their service and the speed and reliability of getting messages to people’s mobiles. When I encountered any issues, a chat with their support quickly resolved them, and they were quick to offer free credits when things weren’t working out as expected.

If you want to send a photo to someone’s phone via MMS (although I’m not sure what the use-case for this might be), you need to first upload the image somewhere online, because the API only accepts a URL. In my case, I would use the Amazon S3 API from the Alexandria PL/SQL Library, then pass the generated URL to the clicksend API. There is a file upload feature that ClickSend provides, I plan to add an API call to take advantage of this which will make this seamless – and provide some file conversion capabilities as well.

    (p_sender  => 'Mr Tester'
    ,p_mobile  => '+61411111111'
    ,p_subject => 'testing mms'
    ,p_message => 'testing '
     || to_char(systimestamp,'DD/MM/YYYY HH24:MI:SS.FF')
    ,p_media_file_url =>

You can send a voice message to someone (e.g. if they don’t have a mobile phone) using the Text to Voice API.

    (p_phone_no     => '+61411111111'
    ,p_message      => 'Hello. This message was sent on '
     || to_char(sysdate,'fmDay DD Month YYYY '
                || '"at" HH:MI am, SS "seconds"')
     || '. Have a nice day.'
    ,p_voice_lang   => 'en-gb' -- British English
    ,p_voice_gender => 'male'
    ,p_schedule_dt  => sysdate + interval '2' minute

You have to tell the API what language the message is in. For a number of languages, you can specify the accent/dialect (e.g. American English, British English, or Aussie) and gender (male or female). You can see the full list here.

All calls to the send_sms, send_mms and send_voice procedures use Oracle AQ to make the messages transactional. It’s up to you to either COMMIT or ROLLBACK, which determines whether the message is actually sent or not. All messages go into a single queue.

You can have a message be scheduled at a particular point in time by setting the p_schedule_dt parameter.

The default installation creates a job that runs every 5 minutes to push the queue. You can also call push_queue directly in your code after calling a send_xxx procedure. This creates a job to push the queue as well, so it won’t interfere with your transaction.

All messages get logged in a table, clicksend_msg_log. The log includes a column clicksend_cost which allows you to monitor your costs. To check your account balance, call get_credit_balance.

Please try it out if you can and let me know of any issues or suggestions for improvement.

Filed under: Oracle, PL/SQL Tagged: Clicksend, PL/SQL

File Upload Improvements in Apex 5.1

Sun, 2016-07-31 22:28

Warning: this is based on the Apex 5.1 Early Adopter and details may change.


The standard File Upload item type is getting a nice little upgrade in Apex 5.1. By simply changing attributes on the item, you can allow users to select multiple files (from a single directory) at the same time.

In addition, you can now restrict the type of file they may choose, according to the MIME type of the file, e.g. image/jpg. This file type restriction can use a wildcard, e.g. image/*, and can have multiple patterns separated by commas, e.g. image/png,application/pdf.


Normally, to access the file that was uploaded you would query APEX_APPLICATION_TEMP_FILES with a predicate like name = :P1_FILE_ITEM. If multiple files are allowed, however, the item will be set to a comma-delimited list of names, so the suggested code to get the files is:

  arr apex_global.vc_arr2;
  arr := apex_util.string_to_table(:P1_MULTIPLE_FILES);
  for i in 1..arr.count loop
    select t.whatever
    into   your_variable
    from   apex_application_temp_files t
    where = arr(i);
  end loop;

You can play with a simple demo here: (login as demo / demodemo).

If you want to support drag-and-drop, image copy&paste, load large files asynchronously, or restrict the maximum file size that may be uploaded, you will probably want to consider a plugin instead, like Daniel Hochleitner’s DropZone.

Filed under: APEX Tagged: APEX, apex-5.1

Interactive Grids (Apex 5.1 EA) and TAPIs

Wed, 2016-06-29 22:37

DISCLAIMER: this article is based on Early Adopter 1.


I’ve finally got back to looking at my reference TAPI Apex application. I’ve greatly simplified it (e.g. removed the dependency on Logger, much as I wanted to keep it) and included one dependency (CSV_UTIL_PKG) to make it much simpler to install and try. The notice about compilation errors still applies: it is provided for information/entertainment purposes only and is not intended to be a fully working system. The online demo for Apex 5.0 has been updated accordingly.

I next turned my attention to Apex 5.1 Early Adopter, in which the most exciting feature is the all-new Interactive Grid which may replace IRs and tabular forms. I have installed my reference TAPI Apex application, everything still works fine without changes.

I wanted my sample application to include both the old Tabular Forms as well as the new Interactive Grid, so I started by making copies of some of my old “Grid Edit” (tabular form) pages. You will find these under the “Venues” and “Event Types” menus in the sample application. I then converted the tabular form regions to Interactive Grids, and after some fiddling have found that I need to make a small change to my Apex API to suit them. The code I wrote for the tabular forms doesn’t work for IGs; in fact, the new code is simpler, e.g.:

PROCEDURE apply_ig (rv IN VENUES$TAPI.rvtype) IS
  r VENUES$TAPI.rowtype;
    r := VENUES$TAPI.ins (rv => rv);
    sv('VENUE_ID', r.venue_id);
    r := VENUES$TAPI.upd (rv => rv);
    VENUES$TAPI.del (rv => rv);
END apply_ig;

You may notice a few things here:

(1) APEX$ROW_STATUS for inserted rows is ‘I’ instead of ‘C’; also, it is set to ‘D’ (unlike under tabular forms, where it isn’t set for deleted rows).

(2) After inserting a new record, the session state for the Primary Key column(s) must be set if the insert might have set them – including if the “Primary Key” in the region is ROWID. Otherwise, Apex 5.1 raises No Data Found when it tries to retrieve the new row.

(3) I did not have to make any changes to my TAPI at all :)

Here’s the example from my Event Types table, which doesn’t have a surrogate key, so we use ROWID instead:

  r EVENT_TYPES$TAPI.rowtype;
    r := EVENT_TYPES$TAPI.ins (rv => rv);
    sv('ROWID', r.p_rowid);
    r := EVENT_TYPES$TAPI.upd (rv => rv);
    EVENT_TYPES$TAPI.del (rv => rv);
END apply_ig;

Converting Tabular Form to Interactive Grid

The steps needed to convert a Tabular Form based on my Apex API / TAPI system are relatively straightforward, and only needed a small change to my Apex API.

  1. Select the Tabular Form region
  2. Change Type from “Tabular Form [Legacy]” to “Interactive Grid”
  3. Delete any Region Buttons that were associated with the Tabular form, such as CANCEL, MULTI_ROW_DELETE, SUBMIT, ADD
  4. Set the Page attribute Advanced > Reload on Submit = “Only for Success”
  5. Under region Attributes, set Edit > Enabled to “Yes”
  6. Set Edit > Lost Update Type = “Row Version Column”
  7. Set Edit > Row Version Column = “VERSION_ID”
  8. Set Edit > Add Row If Empty = “No”
  9. If your query already included ROWID, you will need to remove this (as the IG includes the ROWID automatically).
  10. If the table has a Surrogate Key, set the following attributes on the surrogate key column:
    Identification > Type = “Hidden”
    Source > Primary Key = “Yes”
  11. Also, if the table has a Surrogate Key, delete the generated ROWID column. Otherwise, leave it (it will be treated as the Primary Key by both the Interactive Grid as well as the TAPI).
  12. Set any columns Type = “Hidden” where appropriate (e.g. for Surrogate Key columns and VERSION_ID).
  13. Under Validating, create a Validation:
    Editable Region = (your interactive grid region)
    Type = “PL/SQL Function (returning Error Text)”
    PL/SQL = (copy the suggested code from the generated Apex API package) e.g.

        RETURN VENUES$TAPI.val (rv =>
            (venue_id     => :VENUE_ID
            ,name         => :NAME
            ,map_position => :MAP_POSITION
            ,version_id   => :VERSION_ID
  14. Under Processing, edit the automatically generated “Save Interactive Grid Data” process:
    Target Type = PL/SQL Code
    PL/SQL = (copy the suggested code from the generated Apex API package) e.g.

        VENUES$APEX.apply_ig (rv =>
            (venue_id     => :VENUE_ID
            ,name         => :NAME
            ,map_position => :MAP_POSITION
            ,version_id   => :VERSION_ID

I like how the new Interactive Grid provides all the extra knobs and dials needed to interface cleanly with an existing TAPI implementation. For example, you can control whether it will attempt to Lock each Row for editing – and even allows you to supply Custom PL/SQL to implement the locking. Note that the lock is still only taken when the page is submitted (unlike Oracle Forms, which locks the record as soon as the user starts editing it) – which is why we need to prevent lost updates:

Preventing Lost Updates

The Interactive Grid allows the developer to choose the type of Lost Update protection (Row Values or Row Version Column). The help text for this attribute should be required reading for any database developer. In my case, I might choose to turn this off (by setting Prevent Lost Updates = “No” in the Save Interactive Grid Data process) since my TAPI already does this; in my testing, however, it didn’t hurt to include it.

Other little bits and pieces

I found it interesting that the converted Interactive Grid includes some extra columns automatically: APEX$ROW_SELECTOR (Type = Row Selector), APEX$ROW_ACTION (Type = Actions Menu), and ROWID. These give greater control over what gets included, and you can delete these if they are not required.

Another little gem is the new Column attribute Heading > Alternative Label: “Enter the alternative label to use in dialogs and in the Single Row View. Use an alternative label when the heading contains extra formatting, such as HTML tags, which do not display properly.”.


If you’d like to play with a working version of the reference application, it’s here (at least, until the EA is refreshed) (login as demo / demo):

I’ve checked in an export of this application to the bitbucket repository (f9674_ea1.sql).

Filed under: APEX Tagged: APEX, apex-5.1, interactive-grid, TAPI

Monitoring AWS Costs

Tue, 2016-06-21 00:38

I’ve been running my Apex sites on Amazon EC2 for many years now, and I’ve gone through a number of infrastructure upgrades and price changes over time. I have some alerts set up, e.g. if a server starts getting very busy or if my estimated charges go over a threshold. Today I got an alert saying my estimated monthly bill will be over $100 which is unusual.

One of the most useful reports in AWS is the Instance Usage Reports (found under Dashboard > Reports > EC2 Instance Usage Report). I tell it to report Cost, grouped by Instance Type, which gives me the following:


As you can see, my daily cost was about $1.58 per day, and this shot up on the 16th (note: these rates are for the Sydney region). I was running Oracle on an m1.medium SUSE Linux instance until June 16, when I upgraded it to an m3.medium instance. I have a Reserved Instance (RI) for m1.medium, but not for m3.medium, which is why the cost has shot up. That RI will expire soon; I will purchase an m3.medium RI which will bring the cost of that instance back down to about $1 per day. Until I do that, I will be charged the “On Demand” rate of $4.63 per day.

I’m also running two t2.nano Amazon Linux instances as my frontend Apache servers. Even though they are the smallest available instance type (nano), they barely register over 1% CPU most of the time. I’ve moved all the DNS entries across to one of those nano instances now, so I will soon decommission one which will save me a few extra dollars per month.

As an Apex developer, outsourcing the hardware-related worries to AWS has been the best decision I’ve made. I’ve only suffered a couple of significant outages to date, and in both instances all my servers were still running without issue when connectivity was restored. I can spin up new instances whenever I want, e.g. to test upgrades (you might notice from the graph that I did a test upgrade on an m3.medium instance on June 14).

In case you’re wondering, the total time I needed to take down my Apex instance, take a snapshot, spin up the new instance, and swap the IP address across to it, was about 30 minutes. And that included about 10 minutes lost because I accidentally picked an incorrect option at one point. Not only that, but my upgrade also included changing from magnetic disk to SSD, which seems a bit faster. Overall I’m pretty happy with all that.

Filed under: Oracle

Checkbox Item check / uncheck all

Tue, 2016-06-14 04:00

If you have an ordinary checkbox item based on a list of values, here is a function which will set all the values to checked or unchecked:

function checkboxSetAll (item,checked) {
  $("#"+item+" input[type=checkbox]").attr('checked',checked);

For example:

checkboxSetAll("P1_ITEM", true); //select all
checkboxSetAll("P1_ITEM", false); //select none

It works this way because a checkbox item based on a LOV is generated as a set of checkbox input items within a fieldset.

Note: If it’s a checkbox column in a report, you can use this trick instead: Select All / Unselect All Checkbox in Interactive Report Header

Filed under: APEX Tagged: APEX, javascript, jQuery, tips-&-tricks

Unique constraint WWV_FLOW_WORKSHEET_RPTS_UK violated

Thu, 2016-05-12 19:31

If your Apex application import log shows something like this:

...PAGE 73: Transaction Lines Report
ERROR at line 1:
ORA-00001: unique constraint (APEX_040200.WWV_FLOW_WORKSHEET_RPTS_UK)
ORA-06512: at "APEX_040200.WWV_FLOW_API", line 16271
ORA-06512: at line 6

(this is on an Apex 4.2.4 instance)

This is due to a Saved Report on an Interactive Report that was included in the export, which conflicts with a different Saved Report in the target instance. The log will, conveniently, tell you which page the IR is on.

The solution for this problem is simple – either:

(a) Export the application with Export Public Interactive Reports and Export Private Interactive Reports set to No;
(b) Delete the Saved Report(s) from the instance you’re exporting from.

You can find all Saved Reports in an instance by running a query like this:

select workspace
where application_user not in ('APXWS_DEFAULT'

You can delete Saved Reports from the Application Builder by going to the page with the Interactive Report, right-click on the IR and choose Edit Saved Reports, then select the report(s) and click Delete Checked.

Filed under: APEX Tagged: APEX, problem-solved

Email made Easier

Mon, 2016-04-18 21:51

an e-mail letter that has a @ sign on itSending emails from the Oracle database can be both simply deceptively braindead easy, and confoundingly perplexingly awful at the same time. Easy, because all you have to do is call one of the supplied mail packages to send an email:

  (sender     => ''
  ,recipients => ''
  ,subject    => 'Test Subject'
  ,message    => 'Test Message');
  (p_from => ''
  ,p_to   => ''
  ,p_subj => 'Test Subject'
  ,p_body => 'Test Message'

If you want more control over your emails you can use UTL_SMTP instead; this is what I’ve been using for the past few years because I like feeling in control (doesn’t everyone?).

If you just don’t trust these high-level abstractions you can use UTL_TCP and interact directly with the mail server. I don’t know, maybe your mail server does some weird stuff that isn’t supported by the standard packages.

Let’s make up a checklist of features supported out of the box (i.e. without requiring you to write non-trivial code) and see how they stack up:

APEX_MAIL UTL_MAIL UTL_SMTP UTL_TCP Attachments Yes Yes No* No* Asynchronous Yes No No No Rate limited Yes No No No Anti-Spam No* No* No* No* SSL/TLS Yes No No* No* Authentication Yes No No* No*

Features marked “No*”: these are not natively supported by the API, but generic API routines for sending arbitrary data (including RAW) can be used to build these features, if you’re really keen or you can google the code to copy-and-paste.

(Note: of course, you can add the Asynchronous and Rate limiting features to any of the UTL_* packages by writing your own code.)


Calls to the API to send an email do not attempt to connect to the mail server in the same session, but record the email to be sent soon after in a separate session.

This provides two benefits:

  1. It allows emails to be transactional – if the calling transaction is rolled back, the email will not be sent; and
  2. It ensures the client process doesn’t have to wait until the mail server responds, which might be slow in times of peak load.

Sending an email within an organisation is easy; internal mail servers don’t usually filter out internal emails as spam. Sending an email across the internet at large is fraught with difficulties, which can rear their ugly heads months or years after going live. One day your server tries to send 100 emails to the same recipient in error, and all of a sudden your IP is blocked as a spammer and NO emails get sent, with no warning.

For the last two years I’ve been battling this problem, because my site allows my clients to broadcast messages to their customers and partners via email and SMS. The SMS side worked fine, but emails frequently went AWOL and occasionally the whole site would get spam blocked. Most emails to hotmail went into a black hole and I was always having to apologise to anyone complaining about not getting their emails – “You’re not using a hotmail address by any chance? ah, that’s the problem then – sorry about that. Do you have any other email address we can use?”

I added some rate-limiting code to ensure that my server trickled the emails out. My server was sending about 2,000 to 3,000 per month, but sometimes these were sent in short spikes rather than spread out over the month. My rate-limiting meant a broadcast to 200 people could take several hours to complete, which didn’t seem to bother anyone; and this stopped the “too many emails sent within the same hour” errors from the mail server (I was using my ISP’s mail server).

I managed to improve the situation a little by implementing SPF (Sender Policy Framework). But still, lots of emails went missing, or at least directly into people’s spam folders.

I looked into DKIM as well, but after a few hours reading I threw that into the “too hard basket”. I decided that I’d much prefer to outsource all this worry and frustration to someone with more expertise and experience.

Searching for an Email Gateway

I’ve been hosting my site on Amazon EC2 for a long time now with great results and low cost, and I’ve also been using Amazon S3 for hosting large files and user-uploaded content. Amazon also provides an Email Gateway solution called SES which seemed like a logical next step. This service gives 62,000 messages per month for free (when sent from an EC2 instance) and you just get charged small amounts for the data transfer (something like 12c per GB).

I started trying to build a PL/SQL API to Amazon SES but got stuck trying to authenticate using Amazon’s complicated scheme. Just to make life interesting they use a different encryption algorithm for SES than they do for S3 (for which I already had code from the Alexandria PL/SQL library). It was difficult because their examples all assumed you’ve installed the Amazon SDK.

It always rejected anything I sent, and gave no clues as to what I might be doing wrong. In the end I decided that what I was doing wrong was trying to work this low-level stuff out myself instead of reusing a solution that someone else has already worked out. A good developer is a lazy developer, so they say. So I decided to see what other email gateways are out there.

I looked at a few, but their costs were prohibitive for my teeny tiny business as they assumed I am a big marketing company sending 100,000s of emails per month and would be happy to pay $100’s in monthly subscriptions. I wanted a low-cost, pay-per-use transactional email service that would take care of the DKIM mail signing for me.


In the end, I stumbled upon Mailgun, a service provided by Rackspace. Their service takes care of the DKIM signing for me, do automated rate limiting (with dynamic ramp up and ramp down), it includes 10,000 free emails per month, and extra emails are charged at very low amounts per email with no monthly subscription requirement.

Other benefits I noticed was that it allows my server to send emails by two methods: (1) RESTful API and (2) SMTP. The SMTP interface meant that I was very quickly able to use the service simply by pointing my existing Apex mail settings and my custom UTL_SMTP solution directly to the Mailgun SMTP endpoint, and it worked out of the box. Immediately virtually all our emails were getting sent, even to hotmail addresses. I was able to remove my rate limiting code. Other bonuses were that I now had much better visibility of failed emails – the Mailgun online interface provides access to a detailed log including bounces, spam blocks and other problems. So far I’ve been using it for a few weeks, and of 2,410 emails attempted, 98.55% were delivered, and 1.45% dropped. The emails that were dropped were mainly due to incorrect email addresses in my system, deliberately “bad” test emails I’ve tried, or problems on the target mail servers. One email was blocked by someone’s server which was running SpamAssassin. So overall I’ve been blown away by how well this is running.

Once I had my immediate problem solved, I decided to have a closer look at the RESTful API. This provides a few intriguing features not supported by the SMTP interface, such as sending an email to multiple recipients with substitution strings in the message, and each recipient only sees their own name in the “To” field. My previous solution for this involved sending many emails; the API means that I can send the request to Mailgun just once, and Mailgun will send out all the individual emails.

Another little bonus is that Mailgun’s API also includes a souped-up email address validator. This validator doesn’t just check email addresses according to basic email address formatting, it also checks the MX records on the target domain to determine whether it’s likely to accept emails. For some domains (such as and I noticed that it even does some level of checking of the user name portion of the email address. It’s still not absolutely perfect, but it’s better than other email validation routines I’ve seen.

Note: Mailgun supports maximum message size of 25MB.

Email Validation Plugin

Mailgun also provide a jQuery plugin for their email address validator which means you can validate user-entered email addresses on the client before they even hit your server. To take advantage of this in Oracle Apex I created the Mailgun Email Validator Dynamic Plugin that you can use and adapt if you want.


If you follow me on twitter you are probably already aware that I’ve started building a PL/SQL API to make the Mailgun RESTful API accessible to Oracle developers. You can try it out for yourself by downloading from here if you want. The WIKI on Github has detailed installation instructions (it’s a little involved) and an API reference.

So far, the API supports the following Mailgun features:

  • Email validation – does the same thing as the jQuery-based plugin, but on the server
  • Send email


  (p_from_email => ''
  ,p_to_email   => ''
  ,p_subject    => 'Test Subject'
  ,p_message    => 'Test Message'

The API Reference has a lot more detailed examples.

My implementation of the Send Email API so far supports the following features:

MAILGUN_PKG Attachments Yes Asynchronous Yes Rate limited Yes* Anti-Spam Yes* SSL/TLS Yes, required Authentication Yes

Features marked “Yes*”: these are provided by the Mailgun service by default, they are not specific to this PL/SQL API.

I’m planning to add more features to the API as-and-when I have a use for them, or if someone asks me very nicely to build them. I’ll be pleased if you fork the project from Github and I welcome your pull requests to merge improvements in. I recommend reading through the Mailgun API Documentation for feature ideas.

If you use either of these in your project, please let me know as I’d love to hear about your experience with it.

This article was not solicited nor paid for by Mailgun. I just liked the service so I wanted to blog about it.

UPDATE 26/4/2016: release 0.4 now uses Oracle AQ to enable asynchronous calls.

Filed under: APEX, PL/SQL Tagged: APEX, email, PL/SQL, plug-ins, SMTP

Declarative Tabular Form dynamic totals

Mon, 2016-04-04 22:55

A common Apex project is to take a customer’s existing spreadsheet-based solution and convert it more-or-less as is into Apex. I’ve got one going at the moment, a budgeting solution where users need to enter their budget requests. They currently enter their requests into an XLS template file which generates subtotals and totals for them.

To do this in Apex I’m going to use a tabular form, and to do the subtotals I’ll use jQuery in a way not too dissimilar to that I described earlier.

Here is a mockup of the screen so far:


There are column totals that need to be added up and updated dynamically (indicated by the green arrows) as well as subtotals within each row (indicated by the red arrows).

I started by looking at the generated items, getting their ids (e.g. “f09_0001” etc) and writing the jQuery code to detect changes, add them up, and put the totals in the relevant items. I then started repeating this code for each column, and thought “hmmm”.

There were two problems with this approach that I could foresee:

  1. The generated ids in a tabular form can change if the structure of the query changes  – e.g. what was f08 + f09 => f10 might change to f09 + f10 => f11
  2. I was aware of another form that I would need to build, with a similar structure except that there will be two sets of “Jan-Jun” + “Jul-Dec” columns, each with their own subtotal.

I wanted a more declarative solution, so that the heavy lifting will be done in one set of generic javascript functions, and I simply need to put attributes in the relevant columns to activate them. This is how I’ve approached this:

  • Create the tabular form as usual (mine is based on an Apex Collection) and remove the standard DML processes, replaced with my own that calls APEX_COLLECTION instead.
  • Create a standard report that generates the total items by calling APEX_ITEM.text, with p_attributes=>'data-total="x"' (with a different “x” for each column, e.g. year1).
  • Set the Static ID on the tabular form region (e.g. tabularform).
  • Set Element Attributes on the Jan-Jun column to data-cell="year1" data-col="year1_jan_jun", similarly for the Jul_Dec column.
  • Set Element Attributes on all the Year columns in the tabular form to data-col="yearx", where x is 1..5.
  • Set Element Attributes on the total for the first year to data-subtotal="year1".

The following is the query for the totals report region:

select APEX_ITEM.text(1, TO_CHAR(SUM(year1_jan_jun),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year1_jan_jun"') as year1_jan_jun
      ,APEX_ITEM.text(2, TO_CHAR(SUM(year1_jul_dec),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year1_jul_dec"') as year1_jul_dec
      ,APEX_ITEM.text(3, TO_CHAR(SUM(year1_total),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year1"') as year1_total
      ,APEX_ITEM.text(4, TO_CHAR(SUM(year2_total),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year2"') as year2_total
      ,APEX_ITEM.text(5, TO_CHAR(SUM(year3_total),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year3"') as year3_total
      ,APEX_ITEM.text(6, TO_CHAR(SUM(year4_total),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year4"') as year4_total
      ,APEX_ITEM.text(7, TO_CHAR(SUM(year5_total),'FM999G999G999G999G990D00'), p_size=>10, p_maxlength=>2000,
       p_attributes=>'disabled=true class="edit_money" data-total="year5"') as year5_total
from budget_collection_vw

So, to summarise: all the data-cell items get totalled to the data-subtotal item in the same row; and all the data-col items get totalled to the data-total item below the tabular form.

To do all the hard work, I’ve added the following code to my page’s Function and Global Variable Declaration:

function getSum (qry) {
  //get the sum over all items matching the given jQuery search criterion
  var t = 0;
  $(qry).each(function() {
    t += parseFloat($(this).val().replace(/,/g,''))||0;
  return t;

function updateSubTotal (item) {
  // update a row-level subtotal
  // the items to add up are identified by data-cell="x"
  // the item to show the total is identified by data-subtotal="x"
  var cell = $(item).data("cell") //get the data-cell attribute
     ,rn = $(item).prop("id").split("_")[1]
     ,t = getSum("input[data-cell='"+cell+"'][id$='_"+rn+"']");

  // we need to temporarily enable then disable the subtotal
  // item in order for the change event to fire

function updateTotal (item) {
  // update a column total
  var col = $(item).data("col") //get the data-col attribute
     ,t = getSum("input[data-col='"+col+"']");


The updateSubTotal and updateTotal functions may get moved to my global javascript file later.

I put this in Execute when Page Loads:

$("#tabularform").on("change", "input[data-cell]", function(){
$("#tabularform").on("change", "input[data-col]", function(){

In case you’re wondering, I’m re-using the formatMoney function here.

There’s a number of things happening here. On page load, we add a listener for changes to any input item that has a data-cell attribute; this calls updateSubTotal, which detects the row number for the triggering item, adds up all the values for any input item that has the same data-cell value; and puts the total in the input item with a matching data-subtotal attribute.

We also have a listener for changes to any item with a data-col class; when these are changed, updateTotal adds up any item with the same attribute, and puts the total in an item with attribute data-total.

The jQuery selector [id$='_"+rn+"'] makes sure that the row-level code only finds items ending with the given row number (i.e. '*_0001').

The benefit of this declarative approach is that it is much easier to re-use and adapt.

EDIT: fixed the change trigger so that I don’t need to call updateTotal from updateSubTotal.

Filed under: APEX Tagged: APEX, jQuery, tips-&-tricks