Thursday, 27 September 2018

Oracle Forms to APEX IDE Transition

If you would like a good high level run-down on why Oracle APEX is a great choice to modernise Oracle Forms, have a read of this.

After listening in on the AskTom Office Hours on this topic (make sure you also read the chat transcript), I had a few ideas for posts to help Forms developers transition to APEX, before my Forms knowledge gets too stale!

If you put the Forms & APEX IDEs together, it's not hard to see they're sown from the same cloth, so to speak.

Oracle Forms

Navigator on the left, properties on the right, layout editor in them middle. All with similar behaviours (link to my videos from a while back)

Oracle APEX 5.1, with custom skin
I thought I'd run down some components within the Forms IDE, and add some commentary.

Before you begin...


The key thing to remember when transitioning from Forms to APEX is ... empty the cup.

Web behaviour changes some UX fundamentals, but it's an environment in which you should already be rather fluent. So forget about how you build applications in Forms, and think about how you want your website to behave.

Render vs Process


Forms renders the Form to the pixel from compiled source files, and you can show/hide elements on the canvas upon certain triggers firing.

A user visiting a URL in APEX will have their HTML page dynamically generated by PL/SQL, with a variety of conditions on components that decide if they're included in the render.

After the page is delivered to the browser, Dynamic Actions then respond to events that may happen on the page before the next page submit, which allows validation and processing of all the values on the page, or a page redirect, which just opens the target, leaving page data behind.

Render, Interaction, or Page Process?

The behavioural difference to remember is that the database knows nothing about the values on the web page until you either
1) submit the page (Processing)
2) execute a PL/SQL dynamic action that submits page items to session state

PL/SQL Dynamic Action

Many of your initial problems will probably relate to forgetting to submit/return these values.

Object Navigator Components


Triggers

Straight into a topic with conceptually different behaviours between Forms & APEX. Triggers in Forms drove pretty much everything. You're responding to some event that user has manifested in some way, often driven by moving the cursor.

In a stateful environment, this behaviour is fine, and made Forms powerful. In the web environment, these triggers don't have much of a 1-to-1 translation, but the main analog here might be Dynamic Actions.

Many APEX pages might handle processing when you submit the page, so you may have validations, computations, and processes that fire, based on flexible conditions.

Interactive pages may have dynamic actions that respond to specific clicks, but not submit or refresh the entire page, just some of it. This reduces network traffic, and enables clever user experiences.

Alerts

Half your messages may come the process that fires when you submit the page, to be shown on the subsequent page.

For instance, you could set the value of a common item P0_RESULT within your process, and display it as the success message using the &ITEM. substitution syntax.

Page Process


For Dynamic Actions interacting with the database, you may want to display the same style message.
Check out this example from Martin using the Supplied API.

Or for dialog behaviour where you control button naming, you might consider using a plugin such as Alertify or Pretius Enhanced Notifications.

Alertify Dynamic Action instance

Attached Libraries

APEX takes care of the JavaScript and CSS libraries that support the Universal Theme, which supports all the components you need for flexible, dynamic applications.

You can include your own JavaScript and CSS in several ways, mostly via the page attributes.

Page CSS attributes

You can choose to add inline code, reference files that exist either in the database as a BLOB (#APP_IMAGES#), or sitting on the middle tier, typically served by ORDS, perhaps sitting on a Web Logic Server, prefixing the file location with #IMAGE_PREFIX#.

If you use a decent amount of custom JavaScript, you may wish to consider APEX Nitro.

Data Blocks

As a Forms developer, I remember spending a lot of time managing details of the data block, and they generally either broke up the page into chunks of data, or held buttons & hidden items.

In APEX, you could say similar things about Regions. Each page is broken up into a bunch of regions, which could come in many forms. Check out the Component Templates available in the Universal Theme.

You can even construct master-detail relationships in APEX. There are no Relations to define, but relationship properties are set within the Region attributes.

Editors

I don't recall using Editors much in Forms, but if you want to handle large objects of the character variety, then you might consider the OraOpenSource plugin.

Events

I don't remember using Events, but I believe they allow die-hard Forms developers to extend their application with JavaBeans.

If there is something that APEX doesn't do out of the box, it will probably be worth looking to see if anyone has built a plugin for APEX to do so. Some of these are absolute crackers. Once I did a session on consuming plugins.

LOVs

I think the Record Group element is manifested as an LOV definition now, that can be shared in a number of places.

An LOV in APEX is more coupled with the Item type. A radio group works well with a small handful of values, Select Lists for middle sized sets, and perhaps the Select2 or I really like the Modal LOV plugin for larger sets to be dynamically queried, while still mastering the keyboard entry.
Or you might even define your own modal page to fetch a value.
There is a native Popup LOV, but I don't like it.

Object Groups

Object Groups and Property Classes in Forms are little more vague than the rest, since this was the sort of thing that would be set up once in a blue moon, utilised many times.

I think a comparison for grouping objects in APEX might be item plugins, possibly project specific.

Or maybe blueprints.

Parameters

Page Items are populated between pages to pass information to the next page, such as the selected record in a report.

Declarative Page Target


Larger forms with a number of items are generally submitted as a whole, where the page process handles the data, and branches to the next page.

These values can be protected from URL tampering by session state security, at item, page, and application levels, often by default.

Popup Menus

I've seen explorations of contextual popup menus here, and here.

The APEX team have implemented them within the Page Designer - my favourite is the duplicate option.

Program Units

When I used Forms, the general mantra was to keep code out of item/block level events, and manage packaged procedure calls from within program units.

But we've all seen Forms written with a spectrum of best practices applied. This is where many of the performance problems could lie, especially poorly used post-query triggers.

For Forms to APEX migration projects, this is probably where most of your gold lies - all the business rules you want to keep. Depending on how well the application is written, you might get to re-use a lot of it, but in my experience, few Forms projects used SmartDB concepts.

If you're aiming for a certain % of re-use, don't aim too high. The code in here can be good guide for the developer in refactoring behaviour, but the APEX page(s) could end up looking and behaviour different to what you had in Forms, if only because you're now in a browser. Thought it could be because you've reviewed the business process since the Form was written 2 decades ago, or you've replaced a lot of the keystrokes with button taps.

Property Classes

Property Classes in Forms allowed the developer to utilise common attributes among each instance of a component.

In APEX we can define User Interface Defaults in the data dictionary, so that each time items or reports are created for specific tables or columns, the same features are applied by default.

As for the style of the application, classes could be applied to components that carry a particular look & feel. The Universal Theme has a default skin that can be reconfigured declaratively.

Record Groups

Record groups where just the SQL component of the LOV.

Head to an application's Shared Components, then locate LOVs. They can be dynamically driven by a SQL query, or be statically defined. Static definition allows a variety of conditions to be applied to each entry.

These LOVs can then be associated with Items such as Radio Groups & Select Lists, or with a column in a report, to translate a code to a label.

Reports

Reporting in APEX is a deep rabbit hole. Conceptually, all your reporting can now be inline - live.
Your power users can be given Interactive Reports with a number of runtime manipulation options.
Oracle JET charts can respond to clicks, allowing drill down functionality, in whatever way you want.

Or you could go down the yellow brick road and choose a tool to dynamically generate PDF documents, Excel spreadsheets, Word files etc.

Visual Attributes

Template Options seem to be a fair comparison here, where common group of settings can be tailored to each instance of a component.

Windows

Application workflow differs between Forms and APEX due to the nature of their environments.

In APEX most interactions happen within the browser window, within an inline modal (just a special looking page region), within a page modal. From APEX 5.x this became native and easy, allowing modals to have validations and branches, just like standard pages.

Menus

Forms had specific menu files, controlled by database roles, and there had to be no active users to be able to update the .mmx file.

The menu in APEX can either be across the top, or down the left side. These menus can be statically defined, or dynamically driven, even by the meta-data that is apex_application_pages view. (my link)

Static navigation entries could be controlled by authorisation schemes, or custom conditions.
Dynamic menus can have security tables integrated within the SQL.

There are a few list templates that follow the same data structure, just rendered in different ways.

There is a smaller Navigation Bar at the top right, typically starting with the login/logout buttons.

Canvas

Forms is WYSIWYG, I'm sorry for your loss. An APEX page needs to be rendered in a variety of devices sizes, so items go where the responsive templates tell them to go. You can impact this using the grid layout, but it can take a little while to get the hang of it. Showing the columns helps, particularly with item layout.

Show Layout Columns
APEX also includes a palette of components ready to drag onto the layout editor, which I primarily use to check if items/regions are set to Start New Row or not.

Properties

The Page Designer introduced in APEX 5.0 is rather reminiscent of Oracle Forms, particularly with regard to the ability to edit multiple components at once, only intersecting attributes, and obscuring heterogenous values.

As with Forms, finding the right property can be tricky, or even being aware of its existence.

I highly recommend you take note of the inline help associated with each attribute. I'm sure this content improves with every version, even without inline feedback (hint hint).

Inline Attribute Help

Let me know if you think I've forgotten something vital here, or misaligned features.

Here are some other links on the topic of Forms transition to APEX:

When Forms to APEX Projects get thorny - Rodrigo also responding to the AskTom session
Oracle Forms Migration - Some recent thoughts (that need some revision)
APEX 5 Page Designer walkthrough - my prezi session looking specifically at the Page Designer IDE.
AskTom Checklist
Office Hours Q&A

Wednesday, 19 September 2018

Remove duplicate from APEX collection

One of my favourite SQL analytic functions is row_number(), and I've used it in the past to identify, then remove duplicates.

In this case, I have an APEX collection that represents a session based view history of products/people/events, or whatever your users might be browsing.

I've created an option to consolidate that view history, and remove any record you might have opened more than once.

Collections are a little hard to play with outside of APEX, so I use the create session procedure in the OraOpenSource libraries to simulate an APEX session within SQL Developer.

exec oos_util_apex.create_session(120,'WESLEYS')

For my test case I simulate adding a few entries in my collection, varying a date column slightly.
begin
apex_collection.create_or_truncate_collection('TEST');
apex_collection.add_member('TEST', 'Scott',  p_d001 => sysdate - 5);
apex_collection.add_member('TEST', 'Dmitri', p_d001 => sysdate - 2);
apex_collection.add_member('TEST', 'Lino',   p_d001 => sysdate - 4);
apex_collection.add_member('TEST', 'Scott',  p_d001 => sysdate - 3);
apex_collection.add_member('TEST', 'Joel',   p_d001 => sysdate - 2);
apex_collection.add_member('TEST', 'Sabine', p_d001 => sysdate - 4);
apex_collection.add_member('TEST', 'Penny',  p_d001 => sysdate - 5);
apex_collection.add_member('TEST', 'Scott',  p_d001 => sysdate - 6);
apex_collection.add_member('TEST', 'Jackie', p_d001 => sysdate - 3);
apex_collection.add_member('TEST', 'Joel',   p_d001 => sysdate - 1);
end;
/

Here is a query that will use an analytical function to add a computed column that identifies the most recent entry for any name, and assign it a 1. Any subsequent entries for that name will get a 2, 3, 4 etc.
select seq_id, c001 name
  ,row_number() over 
    (partition by c001 -- look for duplicates in this set of columns
     order by d001 desc -- put records I want to keep first
     ) rn
     ,d001 dt
from apex_collections
where collection_name = 'TEST'
order by name;

In this case, seq_id 1, 5 & 6 represent the records I want to trim from the list.

Duplicate entries highlighted

Turn the query into an in-line view to filter out any records where the row_number() is not 1, as we are not allowed to have window functions in the where clause (ORA-30483).
select seq_id, rn from
 (select seq_id, row_number() over (partition by c001 order by d001 desc) rn
  from apex_collections
  where collection_name = 'TEST'
) where rn != 1;

    SEQ_ID         RN
---------- ----------
         6          2
         1          2
         5          3

Reverse the order by, and I'll keep the first entry instead.
Got more columns that signify uniqueness? Expand the partition by clause.

A standard aggregate query would be able to identify the names of those duplicates, plus how many you have, but no set of records with the unique identifiers to remove. Using min(seq_id) would be insufficient once you more than two entries.
select count(*), c001 name, min(seq_id)
from apex_collections
where collection_name = 'TEST'
group by c001
having count(*) > 1

  C NAME        MN
--- ---------- ---
  2 Joel         6
  3 Scott        1

We can fold the analytical query into a PL/SQL loop and remove the duplicates from my collection.
begin
  << remove_duplicates >>
  for r_rec in (
    select seq_id, rn from
     (select seq_id, row_number() over (partition by c001 order by d001 desc) rn
      from apex_collections
      where collection_name = 'TEST'
    ) where rn != 1
  ) loop
    APEX_COLLECTION.DELETE_MEMBER
      (p_collection_name =>  'TEST'
      ,p_seq             => r_rec.seq_id);
  end loop remove_duplicates;
end anon;
/

Where the resulting collection is minus the older duplicate.
SEQ_ID     NAME        RN DT        
---------- ---------- --- ----------
         2 Dmitri       1 2018-09-16
         9 Jackie       1 2018-09-15
        10 Joel         1 2018-09-17
         3 Lino         1 2018-09-14
         8 Penny        1 2018-09-13
         7 Sabine       1 2018-09-14
         4 Scott        1 2018-09-15

Of course, this is not limited to APEX collections, but it gave me a chance to play with more toys.

Monday, 17 September 2018

Hide region if no data found

I have a diagnostic page where I hide classic report regions that aren't relevant - ie, have no data returned.

Here I create a dynamic action that executes After Refresh of the relevant region.

Dynamic Action definition

The client-side condition evaluates the presence of the .nodatafound class within a classic report, which is present only when no records are returned.

Inspect element of region with no records

The dynamic action then shows/hides the region, depending on the result of the JavaScript expression:
$(this.triggeringElement).find('.nodatafound').length == 1

The triggering element is the region, so find the class within that region, count the result set, and compare to value 1.


Instead of the region itself, this could relate to other components only relevant when records are returned.

As Maxime pointed out in the comments, here I was focussing on classic report regions. The relevant classes you may be looking for include:

  • Classic Report (versatile): nodatafound
  • Interactive Report (IR): a-IRR-noDataMsg
  • Interactive Grid (IG): a-GV-noDataMsg

This can mean there is no need for a server-side condition to test for existence.

With this dynamic action, the region could re-appear upon refresh with results, making the page more interactive without requiring full page submission.

Friday, 14 September 2018

Add record count to collapsed region

I have a diagnostics page where I wanted to display how many records are in a collapsible region's title.

The following is a simple solution, but will only work properly if all records are displayed, and no pagination is used.
Otherwise, check this past post for alternative methods to get the number of rows in a region.

Pick a column in the region and add a class. I chose "cnt".

Column attribute

To be selective, it's always handy to add a static ID to the region.

This is not an 'advanced' feature

Now we're ready to create an After Refresh Dynamic Action on the region, executing the following JavaScript, also firing on initialisation

$('#p99_share .t-Region-title').text('Sharing ('+$('#p99_share .cnt').length+')');

It will relabel region title with the amount of .cnt classes it could find in the region.

The final result looks like this:

Collapsible region with modified title

An alternative that skips the need for a static region ID would be

$(this.trigginerElement).find('.t-Region-title')
   .text('Sharing ('+$(this.trigginerElement).find('.cnt').length+')');

After Refresh Dynamic Action
Edit - Trent offered a more declarative example.

Relatively simple, but effective.


Monday, 10 September 2018

Enhancing the APEX Error Handling Function with Logger

Many, many moons ago, I created an error handling function for Oracle APEX, just like the original sample provided by Patrick Wolf for the 4.1 error handling feature. You'll probably find a strong correlation between the two events.

OK, now what?
We normally see this if an exception was propagated within a PL/SQL Dynamic Action.
In this case I thought it was time for a little upgrade.

I noticed the sample code, now part of the APEX_ERROR documentation, suggested including a reference ID, perhaps from some logging package.
Conveniently, we use such a package, a popular one among the PL/SQL community called Logger.


I glanced through the package specification, and for a moment I thought it was missing a function that returned the new log ID.

I found a procedure with an OUT parameter instead, so here I log some contextual information about the error.
logger_user.logger.ins_logger_logs(
    p_unit_name => 'error_handler' ,
    p_scope => 'apx_util.error_handler' ,
    p_logger_level => logger.g_error,
    p_extra => p_error.component.name
              ||'~'||p_error.component.type
              ||'~'||p_error.message,
    p_text => 'apx_util.error_handler()',
    p_call_stack => dbms_utility.format_call_stack,
    p_line_no => null,
    po_id => l_reference_id
);
Now the user has some context to report. I figured the wording could be softened a little, too ;p

Standard error message, with reference

So if we were to execute the following SQL, we could see further details.
select time_stamp, module, client_identifier, extra
from logger_user.logger_logs
where id = 12292314;
The log message prior to this ID may also help to provide clues as to the problem.

SQL results, slightly redacted

I also wanted to add some convenience to the developer, so I added this same information to the error popup, but only when an active session is also present within the App Builder (or some special privilege present).

Immediate context for the developer

This is toggled by checking a built in substitution string (or my application item). I note this built-in was only documented from 18.1, but I believe it has been present for a while. It's certainly returns a value in 5.1.
l_result.message := 'We had a problem completing this request. '||
    'Please contact IT Support'||
    ' for further investigation. Reference: '||l_reference_id
    ||case when v('F_SEC_DEV') = 'Y' -- anyone with privilege
    -- or has builder open (from oos_util_apex.is_developer)
    or coalesce(apex_application.g_edit_cookie_session_id
               ,v('APP_BUILDER_SESSION')) is not null then
      ' Dev only: '||p_error.component.name
      ||' ~ '||p_error.component.type
      ||' ~ '||p_error.message
    end;
This brightened the day of some of my colleagues.

Wednesday, 5 September 2018

Client Side Dynamic Actions using jQuery Selectors

Consider a data entry page where it might be nice to capitalise the first letter of a person's name, for a number of fields.


I understand I may be anglicising a problem that contains minutia, but focus instead on the thought processes and options we have available using Dynamic Actions.

Let's say we want to create a dynamic action that responds to change on any of those name fields, then runs some JavaScript to apply sentence-case to the name value, before the user submits the page.

We can do this declaratively just using the mouse, APEX will construct a comma delimited list for you as you select page items from the list.

Declarative item selection

But that's not the only way we can nominate components on a web page. The example above might create a selector for those items that is a comma delimited list of IDs.

$('P18_FIRST_NAME,#P18_MIDDLE_NAME,#P18_LAST_NAME');

When we have a look at the underlying HTML defined for these items using Inspect Element, the selector would locate these fields based on the id="P18_FIRST_NAME"

Inspect Element to see underlying details of page components


Alternatively, we could use classes. This is how web developers of any ilk build their web pages. They make up a string that means something to them, then associate some behaviour with it.
You don't need to "define" a class anywhere, but it pays to ensure it's unique, and follows a standard.

In our case, if we could add a class to each item, then we would only need to list one class in the dynamic action.
In some circumstances, this style of coupling behaviour could be more advantageous.

To make "initcap" appear as a class, as shown in the item as highlighted above, add the string to the 'CSS Classes' in the Advanced section of the item properties.


APEX Page Builder makes this task quicker, thanks to behaviour inspired by Oracle Forms - well, some of us ex-Forms programmers will recognise it as such.

If you select multiple items, you can change some properties in bulk.


Over in the properties, we can modify CSS Classes attribute for all three items at once.

Multi-item select in Page Designer

Note the 'Value Placeholder' attribute - this is different for each field, so the delta symbol is shown with the attribute value blued-out. I love this concept.

So back on the dynamic action, we can change the 'Selection Type' to jQuery Selector, and reference the class with the relevant syntax - prefixed with a full-stop, as opposed to the hashtag for IDs.

.initcap

Dynamic action, only when item value all lower case

We also didn't want this behaviour to apply only when all the letters are still lower-case. If the user wants to enter "von Braun", I won't overwrite their particular usage.

So note the client-side condition, emphasis on the 'client'. Most conditions on APEX components are server-side, which generally means they are evaluated during page render - do we or do we not include this button/region/item? Dynamic actions have client side conditions to decide whether to apply the True actions, or the False actions.

$(this.triggeringElement).val().toLowerCase() == $(this.triggeringElement).val()

Here I've referred to the item being triggered using this.triggeringElement, mentioned in the inline help for this particular attribute. Wrapping that expression with $().val() gives me the item value, or I could have used apex.item().getValue. jQuery built in .toLowerCase() does what you would hopefully infer.

As with all things programming, there are many ways to cook an egg, and this goes for setting the value. Here I've define a Set Value action that uses a JavaScript Expression, as there is no need for a round trip to the database server.

True Action - apply change to item value

This expression uses a function I found on Stack Overflow that I was happy with

toProperCase($(this.triggeringElement).val())

I placed in an application level JavaScript file, included via User Interface attributes of the application.
// Turn mcdonald into McDonald
// only run/apply if current string lowercase
// $(this.triggeringElement).val().toLowerCase() == $(this.triggeringElement).val()
function toProperCase(s)
{
  return s.toLowerCase().replace( /\b((m)(a?c))?(\w)/g,
          function($1, $2, $3, $4, $5) { if($2){return $3.toUpperCase()+$4+$5.toUpperCase();} return $1.toUpperCase(); });
}
Most of the JavaScript usage I have in my applications these days tend to be one line, or is some form of expression, so commonly used there is only a small handful.

Don't let a little JavaScript scare you away from enabling useful interactivity for the end user. Dynamic actions do most of the work for you :p