For this year's Australian Oracle User Group conference I decided to consolidate some of my favourite things to do with 3 of my favourite APEX features.
I considered this a bit of a 'lazy' decision, as it didn't really require any new research - but I think sometimes that can produce some good content, since I'm consolidating years of experience into a session.
It did give me a little leverage for one of my Kscope19 abstract submissions - another concept I've been working on for some time now regarding the management of multiple applications acting as one.
Some of my favourite features? I covered Dynamic Actions, of course, plus some use cases for Build Options, and the REQUEST value. Why? Well, check it out.
One thing I learned from this session is to concentrate on the group in the room. I was asked to record my session, which I was happy to do, but I wasn't mic'd up, so I had to spend my time behind the podium so the laptop mic would record my voice. I prefer to move about & show my enthusiasm, but a colleague said I ended up spending too much time looking at my laptop instead of the people in the room.
And in the end, the recording didn't even work!
Connor suggested a better idea would probably be a phone/camera on a tripod. Lesson learned.
I aim to create a few blog posts out of this session, so some of the ideas can be consumed as such, so stay tuned.
Thursday, 6 December 2018
Thursday, 1 November 2018
Lazy Loading Menu Count
I've been using the lazy loading concept demonstrated in Maxime's post quite a lot recently, I'd love to see this as a declarative feature one day.
I also wondered if I could apply this concept to the badge count in the side menu - not slow the page load by a longer running query that populates the count.
Turns out it wasn't that hard, particularly since I already had the jQuery I needed from a previous requirement.
We first need to add a unique class to the link definition, so we can identify the menu item that needs updating.
The label contains the substitution string reference to an application item called LAZY_MENU, that is just computed to zero on each page load.
Surrounded by square brackets, this turns it into the count badge.
Add a dynamic action that executes PL/SQL on Page Load, probably to the global page, though this demo only fires when on page 15.
The demo populates the item based on a query that counts how many columns in my schema, plus a random number, so we can see it change each time.
A subsequent JavaScript action is where the real action is at
A more complete solution may also update LAZY_MENU application item, ready to have reasonably fresh information for the next page load.
Or we could make our queries faster ;p
I also wondered if I could apply this concept to the badge count in the side menu - not slow the page load by a longer running query that populates the count.
Turns out it wasn't that hard, particularly since I already had the jQuery I needed from a previous requirement.
We first need to add a unique class to the link definition, so we can identify the menu item that needs updating.
The label contains the substitution string reference to an application item called LAZY_MENU, that is just computed to zero on each page load.
Surrounded by square brackets, this turns it into the count badge.
Add a dynamic action that executes PL/SQL on Page Load, probably to the global page, though this demo only fires when on page 15.
The demo populates the item based on a query that counts how many columns in my schema, plus a random number, so we can see it change each time.
A subsequent JavaScript action is where the real action is at
$('#t_TreeNav span.lazy-menu')
.closest('div.a-TreeView-content')
.find('span.a-TreeView-badge')
.text($v('P15_COUNT'));
The selector identifies the menu item based on the lazy-menu class entered in the link definition, then traverses the tree to locate the relevant badge, which is then updated to the page item.A more complete solution may also update LAZY_MENU application item, ready to have reasonably fresh information for the next page load.
Or we could make our queries faster ;p
Thursday, 11 October 2018
ODC Appreciation Day : APEX Workspace Activity Logs
Everything gets a special day these days, and thanks to Tim Hall's encouragement, you can enjoy a vibrant display of appreciation for what the Oracle Developer Community embraces about the technology they use daily.
The first year I talked about Dynamic Actions.
Last year I missed the boat - too busy preparing for some holidays.
This year I'd like to lay down my love for a supply of data every APEX developer has access to: apex_workspace_activity_log.
Yup, I'm talking about a log table.
It's enabled in your Oracle APEX applications by default, and inserts a record in a log table every time APEX renders a page, or a dynamic action interacting with the database thanks to a PL/SQL or Refresh action.
Every time a user opens a page, you know when, who, what, why, and how long it took to generate.
We can combine this information to produce a wealth of information. Oracle provides some out of the box under Administration -> Monitor Activity.
I think the first report worth noting is By Weighted Page Performance.
This report multiplies how many times certain pages were loaded by how long it took to load, so ordering gives weight to those pages consuming overall time. Here I've also highlighted the Median column, since that too can be an indicator. A higher average that maintains a low median can indicate outliers, while a raised median really should be looked at.
Fundamentally, we're asking - should I choose to tune a 3 second page that runs once a day, or tune a 1 second page that runs thousands of times a day?
I've taken this information to produce a range of drillable reports, starting with a beautiful OracleJET chart. This starts by day - guess where the weekend is?
Another favourite of mine plots performance over time, allowing me to target specific pages.
It all reminds me of the first time I remember implementing such a practice in Oracle Forms. We had a pre-form trigger that would log who opened which Form when.
Using this information, we could communicate with the business about how often how many people really are using those 'super important' Forms.
Now APEX gives me this information out-of-the-box, and also tells me how long it spent working on each result. Awesome!
It's proof.
Proof that a user has (or hasn't) opened a particular page.
Proof that the application 'isn't running slow', well, the database is certainly ok.
Proof that people are in fact using your application.
From 5.x it also logs the Request value, allowing more granularity than ever before. With this I can do things like measure how often a page 3 is opened from page 1 vs page 2. Where are users clicking to navigate?
So thank you, Oracle APEX team, for continuing to baking such a resourceful feature into the product.
I use it every day.
#ThanksODC
Further reading:
- Start reading related documentation here.
- Martin shows us how to get started with archiving this data. It is possible to change the interval between the background table switching.
- Jeff offers an example showing recent users of APEX.
- I removed outliers in this post.
- I pasted a few other SQL examples in this forum question.
The first year I talked about Dynamic Actions.
Last year I missed the boat - too busy preparing for some holidays.
This year I'd like to lay down my love for a supply of data every APEX developer has access to: apex_workspace_activity_log.
Yup, I'm talking about a log table.
It's enabled in your Oracle APEX applications by default, and inserts a record in a log table every time APEX renders a page, or a dynamic action interacting with the database thanks to a PL/SQL or Refresh action.
Every time a user opens a page, you know when, who, what, why, and how long it took to generate.
select apex_user as who ,application_id||':'||page_id as what ,view_date as when ,elapsed_time as how_long ,page_view_type as why ,request_value as more_why from apex_workspace_activity_log where application_id >= 4000 and apex_user != 'nobody'
 |
| How APEX Builder dashboard knows who's been the busiest developer |
We can combine this information to produce a wealth of information. Oracle provides some out of the box under Administration -> Monitor Activity.
I think the first report worth noting is By Weighted Page Performance.
 |
| Packaged Reports |
This report multiplies how many times certain pages were loaded by how long it took to load, so ordering gives weight to those pages consuming overall time. Here I've also highlighted the Median column, since that too can be an indicator. A higher average that maintains a low median can indicate outliers, while a raised median really should be looked at.
 |
| Weighted Page Performance |
Fundamentally, we're asking - should I choose to tune a 3 second page that runs once a day, or tune a 1 second page that runs thousands of times a day?
I've taken this information to produce a range of drillable reports, starting with a beautiful OracleJET chart. This starts by day - guess where the weekend is?
 |
| OracleJET Plots Pretty Popular Page Performance |
Another favourite of mine plots performance over time, allowing me to target specific pages.
It all reminds me of the first time I remember implementing such a practice in Oracle Forms. We had a pre-form trigger that would log who opened which Form when.
Using this information, we could communicate with the business about how often how many people really are using those 'super important' Forms.
Now APEX gives me this information out-of-the-box, and also tells me how long it spent working on each result. Awesome!
It's proof.
Proof that a user has (or hasn't) opened a particular page.
Proof that the application 'isn't running slow', well, the database is certainly ok.
Proof that people are in fact using your application.
From 5.x it also logs the Request value, allowing more granularity than ever before. With this I can do things like measure how often a page 3 is opened from page 1 vs page 2. Where are users clicking to navigate?
So thank you, Oracle APEX team, for continuing to baking such a resourceful feature into the product.
I use it every day.
#ThanksODC
Further reading:
- Start reading related documentation here.
- Martin shows us how to get started with archiving this data. It is possible to change the interval between the background table switching.
- Jeff offers an example showing recent users of APEX.
- I removed outliers in this post.
- I pasted a few other SQL examples in this forum question.
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.
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)
I thought I'd run down some components within the Forms IDE, and add some commentary.
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.
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.
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
Many of your initial problems will probably relate to forgetting to submit/return these values.
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.
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
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.
You can include your own JavaScript and CSS in several ways, mostly via the page 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.
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.
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.
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.
I think a comparison for grouping objects in APEX might be item plugins, possibly project specific.
Or maybe blueprints.
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.
The APEX team have implemented them within the Page Designer - my favourite is the duplicate option.
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.
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.
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.
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.
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.
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.
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.
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).
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
APEX for Forms Developers - Kscope presentation
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 |
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 |
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
APEX for Forms Developers - Kscope presentation
Wednesday, 19 September 2018
Remove duplicate from APEX collection
One of my favourite SQL analytic functions is
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.
For my test case I simulate adding a few entries in my collection, varying a date column slightly.
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.
In this case, seq_id 1, 5 & 6 represent the records I want to trim from the list.
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).
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
We can fold the analytical query into a PL/SQL loop and remove the duplicates from my collection.
Where the resulting collection is minus the older duplicate.
Of course, this is not limited to APEX collections, but it gave me a chance to play with more toys.
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 |
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.
The client-side condition evaluates the presence of the
The dynamic action then shows/hides the region, depending on the result of the JavaScript expression:
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:
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.
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 == 1The 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".
To be selective, it's always handy to add a static ID to the region.
Now we're ready to create an After Refresh Dynamic Action on the region, executing the following JavaScript, also firing on initialisation
It will relabel region title with the amount of
The final result looks like this:
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+')');
Edit - Trent offered a more declarative example.
Relatively simple, but effective.
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 |
Relatively simple, but effective.
Subscribe to:
Posts (Atom)