Dynamic Charts

Whenever you need to create a chart with multiple series, you will go there and hardcode those series, creating an almost identical SQL for each one of them. As long as your values remain the same, that will be ok. But what if they change? Actualy, the solution is pretty simple - you need to create a PL/SQL Block to return all the series in one SQL. This example in my Demo Application shows how to write such a Function.



If you replace the column and table names, you can use the same function for all of your charts with multiple series.

Enjoy.

Tabular Form - Checkbox for Setting values to 'Y' or 'N'

This is also one of frequently asked question in the Apex Forum:

http://forums.oracle.com/forums/thread.jspa?threadID=493243

http://forums.oracle.com/forums/thread.jspa?threadID=714172

Using a checkbox for deleting rows is fine, but how do you use it if you want to flag the records and have a value updated depending on the checkbox status (valid/invalid, yes/no)?

It was Patrick Wolf who initially helped me to understand how a checkbox array works. He also created an example (on the fly) to show this can be managed. However, this example was based on a standard tabular form and it couldn't be reporoduced by many interested visitors of my Demo Application. Since this question has been repeated several times in the last couple of weeks, I decided to create a new example, which is based on a manual tabular form.



So, if you have a similar requirement, which is there in many cases, you may want to have a look here:

http://apex.oracle.com/pls/otn/f?p=31517:219

Validation with Ajax

As soon as you need to do some date or number validations using javascript, you will notice how cumbersome that attempt could be. Just recently, I had to programm an application which needed some date and number validations prior to the page submittion. I found that using ajax and letting your database do those kind of cheks is a quite elegant way.

In my Demo Application you will find an example

http://apex.oracle.com/pls/otn/f?p=31517:217

showing how easy it is to set it up.

Especially the date validation is funny. It will accept all kinds of date formats:

sep/15.08 03:16:00 AM

sep.15-08 03:16:00 AM

sep/15/08 03

and it will, of course, give you a user friendly message if you go too far and try entering something like this:

14.15-08 03:16:00 AM



or for

10.15-08 13:16:00 AM

you will receive



Try changing your browser language settings from english to any other language and do the excercise again.

OOW

It is time to get my luggage prepared for a long trip to San Francisco. This will be my first OOW. The trip will be long and exhausting but I am happy because I will get a chance to meet many of my colleagues, the most of which I know only through emails or the oracle forums.



I will arrive on Saturday afternoon and stay there till Thursday evening. These will be five exciting days and the programm is starting already on Sunday. I was invited by Dimitri Gielis to participate in the "Ask the Experts" session together with some well known names from the apex community: John Scott, David Peake, Scott Spendolini and Anton Nielsen.



Also, Dimitri announced an Apex Meetup on Tuesday evening.

The target is to catch as many apex sessions as possible. Unfortunatelly, some of them are starting at the same time. It will be hard to make a decission which one to take.

I will stay at the King George hotel, which is on a walk distance to the Moscone Center.

So, if you are also attending this great event and you are interested in apex, there is a good chance we will meet there.

Oracle Forums Splash

I got this message at least five times today:


at http://www.oracle.com/splash/forums/index.html.

Having to read this for the fifth time, I was just asking myself what sense do these couple of sentences make.

"Oracle forums is experiencing technical difficulty."

So, what kind of a technical difficulty are you experiencing day by day since almost a month? Furthermore: how long is this going to last? Another month? Or two? Any ideas?

"We are aware of the issue and are working as quick as possible to correct the issue."

Hm, are you sure you are?

"Please try again in a few moments."

Well, I did but it still doesn't work.

"We apologize for any inconvenience this may have caused."

Nice to know.

"To speak with an Oracle sales representative: 1.800.ORACLE1."

What should I tell him?

"To contact Oracle Corporate Headquarters from anywhere in the world: 1.650.506.7000."

I don't think they would want to talk to me.

"To get technical support in the United States: 1.800.633.0738."

Unfortunatelly, I belong to the rest of the world.

Guys, if this continues, I will never ever collect enogh points to become a guru.

What's wrong with the Oracle Forum?

As you probably noticed, the forums are either:

- not available at all or

- taking a lot of time to load or

- if they ever load, they are not working properly and showing errors if you try to create or update a posting.

If you manage to load those pages, you will notice that there are some new featueres implemented. Some of them are usefull. Like the new text editor (I realy like that one). Some of them are however questionable:

- the new reward system where you can get some points if you provide a helpfull or even a correct answer. The funniest thing is that the asker is supposed to say the answer someone provided is "correct".

- the fonts were changed to 11px which is not readable at all,

- the visited property they implemented are i.m.h.o. unneccessary because of the image showing if the posting was opened before or updated since. It is anoying too. Hard to read because of the grey color on a grey background.

I already asked the people who set it up if they are realy sure this makes sense. They didn't answer. Well, I am probably not the only one who asked.

Despite of the changes made, features I like or those I don't like, the most important thing though is the availability of the forum. And the fact is - it is not available since almost a week. Have they done a test before they upgraded? How did they test it? Did they ask the comunity about the changes? Maybe they should roll it back once again and consider a redisign using ApEx.

Oracle Text in Five Short Steps

Almost every application I create contains a BLOB (file) table for storing files available for a download. In the most of the cases it will store some documentation related to the application - user manuals, howto's and similar stuff. The download functionality is a nice thing but how about searching the content of those files? There are some examples arround showing how to do that in ApEx but in my opinion the most of them are far to complex. I created an example in my Demo Application, showing how to do that in less than five minutes:

http://apex.oracle.com/pls/otn/f?p=31517:76



This example includes the most frequently used functionalities:

1. mixed case search

2. highlighted snippets

3. index synchronization on commit

If you need more, you can always look into the Oracle Text Documentation.

Enjoy.

Form Validation and User Friendly Messages

I am getting this kind of questions quite often:

"I have report with form for modifications. After clicking on the link the form related to this report pops up. Often this is done by at least two users trying to modify one and the same record simultaneously. In such cases the application raises - "ORA-20001: Current version of data in database has changed since initiated update process. Error Unable to process row ....(table name)".

Could you give some advice or give and example how to handle this in a more user friendly manner?"

I created an example in my Demo Application showing how this can be done:

http://apex.oracle.com/pls/otn/f?p=31517:210

which also includes a step by step guideline.



There, you may test the validation by starting a concurrent update process and trying to update the data on the parent page.

Add Rows to a Standard Tabular Form using Item Value

There are many threads regarding this issue in the forum. Many of them without any answer. So, how do you add rows to your standard tabular form based on an item value?
If you follow this example:

http://apex.oracle.com/pls/otn/f?p=31517:209

you will see that you need three small adjustments to the standard process:

1. extend your SQL using UNION_ALL by adding a small SQL selecting NULL's from DUAL followed by CONNECT BY LEVEL <= :P1_ADD_ROWS_ITEM,

2. add a conditional branch, first in the sequence, passing a request ADD to your page

3. do a modification to the standard add rows process to add 0 rows

and there you go. You don't need to write a manual process to get that functionality
applied on your standard tabular form.



Enjoy.

Dynamic Tabular Form

It can happen that you get a requiremen similar to this one:

http://forums.oracle.com/forums/thread.jspa?threadID=691046

1. You have an unknow number of tables

2. You don't know the structure of the tables in advance

3. You still need forms for entering and maintaining data

The only solution that comes to my mind are dynamically created tabular forms. Tabular forms have already a bad reputation. Now, if you add the word "dynamical" to it, it will sound even more horrorful.

As I promised in the mentioned thread, I tried to create a working example. This is what I came up with:

http://apex.oracle.com/pls/otn/f?p=31517:195

It took me arround three hours to get that code together. Of course, this can be done much better - using a package and providing some additional functionalities like validations and other item types.

Multiple Cascading Select Lists (again)

This is an issue for many developers. I see a lot of questions and receive a lot of mails on this topic. I thought that demonstrating how to do that with two items would be enough to guess how to do it with more than that, since the approach is the same. However, there is nothing better than a step by step guide to get it working.

You will find the extended example here:

http://apex.oracle.com/pls/otn/f?p=31517:119



My advice, from what I have seen so far debuging the other people examples, is to:

1. be carefull with copy-paste and before you do it, think of replacing the given item , table and procedure names with your own,

2. test your on-demand processes in the SQL workshop first, to see if they run,

3. avoid multiplying your code through copy-paste. This makes it much easier to debug and

4. if you have no experience with a similar solution, try to reduce your scope and do it on a simple example first. Try using emp, dept tables like I do it in my Demo Application.

Enjoy.

Default Sorting of a Report

This was an interesting question:

"My requirement is Report should always display the original sequence (in the same way if I run the report in TOAD or SQL*PLUS, ...) and when I click the column heading then only it should do the actual sorting. Now, as soon as I set the sortable attribute to YES for a column and running the report for the first time... it's doing the sorting based on the that column."

So, how do you do that? Normaly, if you enable sorting on an apex report, it will save the sorting preference per user in an item and will call this preference next time you login.

I used the rownum to display the "original sequence" on initial load of the page and enabled the sorting on that column as well. Putting this column to be the first in the row on columns with enabled sorting and hiding it would do the trick. The second thing I did was to remove the sorting preference on the initial load and keep the rownum ordering as long as the user decides to sort the report.

You can view a working example here:

http://apex.oracle.com/pls/otn/f?p=31517:13

How to post your code in the Oracle Forum

This may have been already posted somewhere else. However, I still see people not knowing how to post their code properly. If you want to show your code in a posting on

http://forums.oracle.com

use the following tags and put your code between them

[code]

[/code]

This will show your code formated and readable like this

SELECT CASE
          WHEN cnt > 20
             THEN '<font color="red">' || cnt || '</font>'
          WHEN cnt <= 20
             THEN '<font color="green">' || cnt || '</font>'
       END AS x
  FROM "MYTABLE"
 WHERE TO_CHAR ("MYTABLE"."DATE", 'YYYY-MM-DD') >= '2007-04-01'
   AND "MYTABLE"."SERVCODE" <> 'OBS'

instead of something like this

SELECT CASE WHEN COUNT > 20 THEN '' || cnt || '' WHEN COUNT <= 20 THEN '' || cnt || '' END AS X from "MYTABLE" where TO_CHAR ("MYTABLE"."DATE",'YYYY-MM-DD') >='2007-04-01' and "MYTABLE"."SERVCODE" <>'OBS'

ApEx - Shopping Cart

There is a new example in my Demo Application showing how to create a simple shopping cart using Ajax and DHTML tipps from Carl Backstrom. This demo doesn't require a single submit and it shows how to utilize DHTML and Ajax to operate on collections. Since there is quite a bit of code and I am fairly busy at the moment, all the code is available only to those who have an admin login to my workspace.



You will find the example here:

http://apex.oracle.com/pls/otn/f?p=31517:159

Enjoy digging into it.

Over 500 named users of my Workspace

I started with the registration somewhere in January/February of this year. Up to now, more than 500 people applied for a login.


Within these five to six moths I answered arround 1200 emails regarding account and also many other questions related to ApEx. The number of emails I am getting per day is quite constant and I still haven't noticed a trend of those emails decreasing.

Sorting with ROWNUM

Creating a query and including the ROWNUM will work only for those reports, with disabled column sorting. Once you enable the column sorting, the ROWNUM will not show the right order. This is because ApEx does the sorting after determining the ROWNUM.

A simple trick can help you to overcome this issue. Just escape the ApEx internal #ROWNUM# like this:

SELECT '#ROWNUM#' SEQUENCE, empno, ename, sal
  FROM emp;

and it will give you the right ROWNUM regardless of your sorting.



You can see that working in this example in my Demo Application.

Pipelined Functions

The question in the forum was:

I need to allow my users to type in a list of names and return the names that are not in a table.

1. User types [ Tom Joe Bob MIKE ] into a Text Area item named :P2_NAME_CHECK

2. A table named CUST contains two rows with TOM and Bob in the 
   CUST_NAME column.

3. A report returns two rows JOE and MIKE. 

Usually, it is oposite. You want to show the list of users that match the criteria.

The solution for this problem is quite easy if you know how to use pipelined functions. This is a case where the pipelined functions shine. I created an example in my Demo Application showing how this can be done.



Basically, the pipelined function will create a row for all substrings returning no rows from the emp table, showing those substrings as rows.

Textfield Item - Submitting the Page

Normaly, if there are page items of type "Text Field" they will not submit the page unless you change them to "Text Field (always submits page when Enter pressed)". If you have only one item on you page of type "Text Field" this behaviour changes and the page will always submit if you press "Enter". Sometimes, you don't want this to happen. Especially, if you have some javascript attached to your field. To avoid that you can use the following trick:

1. create another item on you page of type "Text Field",

2. in the "HTML Form Element Attributes" of that item put

style="display:none"

The result is that the second item will not be displayed and the first item will not submit on pressing "Enter".

Two Tabular Forms on one Page

Recently there have been several discussions in the forum regarding multiple tabular forms on one page. I thought it is easy if you know how to create one tabular form manually, you will be able to do it for any other number of those forms. However, many participants of the forum do not share my opinion. This is why I decided to create a very basic example showing how that works. You will find it in my Demo Application together with the required code. If you want to see all the details, you may apply for an account following the instructions on the login page of my Demo Application.



Have fun.

Problems loading Oracle Forums in a browser?

I had this with my old laptop and thought that is my "overloaded" FireFox with all those extensions. However, that continued with my new notebook as well. Now, I noticed this is not only FireFox but also the same thing happens when I use Internet Explorer (which I use only then when I need to open the same ApEx application twice).

See the picture below. It looks like while loading the forum the page is not rendered completely. This behaviour is only there when using Oracle Forums and they happen in both cases - while loading the main page or a single thread. Therefor my question to all readers of this blog: have you ever noticed something like that? I have this from time to time regardless of the connection I use. Currently, I use DSL 16000.

Limit or Extend a Datepicker in ApEx

I have received a couple of questions per email, similar to this one on limiting the value of a date picker item. That shows this is an issue that needs to be solved from the development team. Whereby this is an easy issue. If you look behind the code, you will se there are one procedure and one view involved. The procedure code is generating a small pop-up window showing a calendar based on the number of the years the view is returning. I managed to get that customized by doing the following:

First of all, create a package like this:

1.

CREATE OR REPLACE PACKAGE limit_datepicker
AS
   x   NUMBER;
   y   NUMBER;

   FUNCTION get_x
      RETURN NUMBER;

   FUNCTION get_y
      RETURN NUMBER;

   PROCEDURE show_as_popup_calendar (
      p_request              IN   VARCHAR2 DEFAULT NULL,
      p_title                IN   VARCHAR2 DEFAULT NULL,
      p_yyyy                 IN   VARCHAR2 DEFAULT NULL,
      p_mm                   IN   VARCHAR2 DEFAULT NULL,
      p_dd                   IN   VARCHAR2 DEFAULT NULL,
      p_hh                   IN   VARCHAR2 DEFAULT NULL,
      p_mi                   IN   VARCHAR2 DEFAULT NULL,
      p_pm                   IN   VARCHAR2 DEFAULT NULL,
      p_element_index        IN   VARCHAR2 DEFAULT NULL,
      p_form_index           IN   VARCHAR2 DEFAULT NULL,
      p_date_format          IN   VARCHAR2 DEFAULT 'MM/DD/YYYY',
      p_bgcolor              IN   VARCHAR2 DEFAULT '#336699',
      p_white_foreground     IN   VARCHAR2 DEFAULT 'Y',
      p_application_format   IN   VARCHAR2 DEFAULT 'N',
      p_lang                 IN   VARCHAR2 DEFAULT NULL,
      p_application_id       IN   VARCHAR2 DEFAULT NULL,
      p_security_group_id    IN   VARCHAR2 DEFAULT NULL,
      p_start_year           IN   NUMBER DEFAULT 1919,
      p_end_year             IN   NUMBER DEFAULT 2050
   );
END limit_datepicker;
/

CREATE OR REPLACE PACKAGE BODY limit_datepicker
AS
   FUNCTION get_x
      RETURN NUMBER
   IS
   BEGIN
      RETURN limit_datepicker.x;
   END get_x;

   FUNCTION get_y
      RETURN NUMBER
   IS
   BEGIN
      RETURN limit_datepicker.y;
   END get_y;

   PROCEDURE show_as_popup_calendar (
      p_request              IN   VARCHAR2 DEFAULT NULL,
      p_title                IN   VARCHAR2 DEFAULT NULL,
      p_yyyy                 IN   VARCHAR2 DEFAULT NULL,
      p_mm                   IN   VARCHAR2 DEFAULT NULL,
      p_dd                   IN   VARCHAR2 DEFAULT NULL,
      p_hh                   IN   VARCHAR2 DEFAULT NULL,
      p_mi                   IN   VARCHAR2 DEFAULT NULL,
      p_pm                   IN   VARCHAR2 DEFAULT NULL,
      p_element_index        IN   VARCHAR2 DEFAULT NULL,
      p_form_index           IN   VARCHAR2 DEFAULT NULL,
      p_date_format          IN   VARCHAR2 DEFAULT 'MM/DD/YYYY',
      p_bgcolor              IN   VARCHAR2 DEFAULT '#336699',
      p_white_foreground     IN   VARCHAR2 DEFAULT 'Y',
      p_application_format   IN   VARCHAR2 DEFAULT 'N',
      p_lang                 IN   VARCHAR2 DEFAULT NULL,
      p_application_id       IN   VARCHAR2 DEFAULT NULL,
      p_security_group_id    IN   VARCHAR2 DEFAULT NULL,
      p_start_year           IN   NUMBER DEFAULT 1919,
      p_end_year             IN   NUMBER DEFAULT 2050
   )
   IS
   BEGIN
      limit_datepicker.x := p_start_year;
      limit_datepicker.y := p_end_year;
      wwv_flow_utilities.show_as_popup_calendar (p_request,
                                                 p_title,
                                                 p_yyyy,
                                                 p_mm,
                                                 p_dd,
                                                 p_hh,
                                                 p_mi,
                                                 p_pm,
                                                 p_element_index,
                                                 p_form_index,
                                                 p_date_format,
                                                 p_bgcolor,
                                                 p_white_foreground,
                                                 p_application_format,
                                                 p_lang,
                                                 p_application_id,
                                                 p_security_group_id
                                                );
   END;
END limit_datepicker;
/

2. GRANT EXECUTE ON limit_datepicker TO PUBLIC;

3. CREATE OR REPLACE PUBLIC SYNONYM limit_datepicker FOR <<your_schema>>.limit_datepicker;

To be able to limit the values the view returns you need to do the following:

1. log in a SYS

2. ALTER SESSION SET current_schema=FLOWS_030000 (yor flows schema, FLOWS_030000 in my case)

3.

CREATE OR REPLACE VIEW wwv_flow_years
AS
   SELECT     NVL (b.start_year - 1, 1918) + LEVEL
         FROM DUAL a,
              (SELECT limit_datepicker.get_x start_year
                 FROM DUAL) b,
              (SELECT limit_datepicker.get_y end_year
                 FROM DUAL) c
   CONNECT BY LEVEL < NVL ((c.end_year + 1) - (b.start_year - 1), 
                           2051 - 1918)

The view will now return the same result for the standard date picker or the value you request if you use the custom date picker.

And finaly, create the following on your page, which will contain the date picker item, limiting the years to the values you determine;

1. Create a hidden item on your page (Page 1 in my case)

P1_SECURITY_GROUP_ID

with a source PL/SQL Expression or Function

htmldb_custom_auth.get_security_group_id

2. Create the javascript and put it in the header of your page. Please note, you need to take care of the parameters yourself - for example p_yyyy or p_mm:

<script type="text/javascript">
function f_popup_date(p_this) 
{     
   var item_name = $x(p_this).name
   var app_id = &APP_ID.
   var sec_gr_id = $x('P1_SECURITY_GROUP_ID').value

       w = open("limit_datepicker.show_as_popup_calendar" +
                   "?p_element_index=" + escape(item_name) +
                   "&p_form_index=" + escape('0') +
                   "&p_date_format=" + escape('DD-MON-RR') +
                   "&p_bgcolor=" + escape('#666666') +
                   "&p_dd=" + escape('') +
                   "&p_hh=" + escape('') +
                   "&p_mi=" + escape('') +
                   "&p_pm=" +
                   "&p_yyyy=" + escape('2008') +
                   "&p_lang=" + escape('en') +
                   "&p_application_format=" + escape('N') +
                   "&p_application_id=" + escape(app_id) +
                   "&p_security_group_id=" + escape(sec_gr_id) +
                   "&p_start_year=" + escape('2007') +
                   "&p_end_year=" + escape('2008') +
                   "&p_mm=" + escape('01'),
                   "winLov",
                   "Scrollbars=no,resizable=yes,width=258,height=210");
       if (w.opener == null)
         w.opener = self;
       w.focus();
}
</script>

You will need to replace the values to what you need (2007 to 2008 in my case).

3. Date-Picker Item (P1_DATE_FROM in my case) is a normal text item with the following code in the Post Element Text:

<a href="javascript:f_popup_date('P1_DATE_FROM');">
<img src="/i/asfdcldr.gif" 
style="cursor:pointer;valign:bottom" /></a>

The downside of this approach is that you need to modify one of the apex views and take care you recreate it after the next update. I still didn't have time to find out why this doesn't work on XE. I will have a look into that issue soon and post the results here.

Cascading Select List in a Tabular Form

This is something the most of the ApEx Developers have a problem with. How do I create a cascading select list in a tabular form? There are several examples (also in my Demo Application) on how to do that in a simple form. However, there is only one example arround showing how this can be done - in Vikas application, but I don't like that approach. I have also been asked several times to create such an example. Here we go! In my Demo Application you will find a working example showing also how to create an update and delete process + some javascript for checking and highlighting of all rows in your tabular form:

http://htmldb.oracle.com/pls/otn/f?p=31517:176



This approach is using apex_item + the same javascript (ajax) code as for the "simple" cascading select list.

Apply for an account if you would like to see all of the code behind this example.

XE Webfolder with Vista

If you work with Vista and would like to create a Web Folder according to this tipp from Dietmar Aust, you will not be successful. In Vista there are some changes made and the path described in the above post will give you a view only.

In Vista you need to do the following:

1. Open Windows Explorer and go to Menu Tools / Map Network Drive

2. There, you click on "Connect to a Web site that you can use to store your documents and pictures"

3. Click two times on "Next" (don't ask me why!)

4. Enter http://127.0.0.1:8080/i where it asks you for an Internet or Network address,

5. Enter system / password

6. Give your connection a name

7. Finish.

Now, the images directory will appear in your Windows Explorer under Webfolder:

ApEx Training - München 02.06.2008 - 04.06.2008

Liebe ApEx-ler,

Unser nächstes Training - Fortgeschrittene Techniken aus der Praxis - wird in München im Arabella Sheraton Westpark Hotel stattfinden. Die Details für die Anmeldung findet Ihr auf Opal Consulting.

Wir versprechen (und halten):

- Interessante und neue Inhalte
- hohen Praxisbezug
- Kompetenz in Oracle und ApEx Themen
- Antworten auf alle Ihre Fragen

und freuen uns Euch dort begrüssen zu dürfen.


----------------------------------------------------------------------------------------------------------------------
Our next Training will be held in Munich from 02.06.2008 to 04.06.2008 in Arabella Sheraton Westpark Hotel. The details you can find on Opal Consulting. Please note that places are limited and there has been a great deal of interest in the training following the previous event in March 2008. We advise you to register a.s.a.p.

ApEx Training - followup

This was my first ApEx-only training. I can't remember when I last time spoke in front of that many people (at school perhaps). However, this was an amazing experience. ApEx is really something special - amazing people, exciting topics and a lot of enthusiasm. Also, there were 8 female attendees at our training which I think is great quote. Here some pictures from our training (actually, we were so busy that we managed to take only these two ;)):






The program schedule was quite well loaded and we didn't manage to elaborate on everything. Our schedule was also quite aggressive - training from 9 - 17.30 and QA Sessions from 19 to 21 (planned time - indeed it was 23 when we quit). Amazing to see 80% of the attendees sitting there at 7 in the evening preparing for the QA.

Tomorrow, we will post the details of our next training in Munich.

Manual Tabular Form

Today, I answered an interesting question in the ApEx Forum. Basically, the requirement was to have a tabular form which allows only new records to be edited. Tabular forms are a powerful feature but also something the most of the ApEx developers have a problem with. The manual from the How-To's is outdated, confusing and it is also incorrect in several issues. Also, there are not many other resources in the community dedicated to the problem of operating with tabular forms. This is why I decided to create an example showing several important techniques for mastering this topic. I also posted the most of the code you need to get it working that way:

- highlighting selected rows
- validating the checksum
- disabling columns not allowed for editing
- adding rows to tabular form (one or multiple)
- operating with apex_item package

See the example in my Demo Application. If you want to see more, you may send me an email and join the group of 250 registered users of my Workspace.



A similar example was one of the topics in our training two weeks ago and was created by Patrick Wolf and myself.

ApEx Training - Update

This posting is targeting the German ApEx comunity and is therefor also posted in German language:

Hallo liebe ApEx-ler. Unser Kurs im März http://www.opal-consulting.de/training ist leider seit etwa zwei Wochen ausgebucht. Wir planen einen neuen für Anfang Juni in München, da die Anfrage unerwartet gross ausfiel. Gleich nach dem Abschlus vom Training im März, werden wir den neuen Termin auf unserer Seite publizieren. Falls Sie bis dahin nicht warten wollen, können Sie uns auch gerne eine E-Mail an training@opal-consulting.de zuschicken und einen Platz vorreservieren.

Hello ApEx community. Our Workshop in March http://www.opal-consulting.de/training has been fully booked since almost two weeks. We are planing another one beginning of June in Munich. We will post the details right after the workshop in March.

ApEx Flashchart Headache

Something like this can drive you nuts. I lost several hours trying to figure out why something that is supposed to work (and I do see it working), doesn't work for my customer. I created a simple drill-down chart and did my usual testing. After completing the work, I forwarded it to my customer to see if everything is as they expected. However, they complained it didn't show the right values. It took me a while to remember I answered one similar question in the forum here by proposing a workarround. I do my work in FF and my customer uses IE. There we go.

The problem seem to be simple - IE doesn't refresh a flash chart once the link has been used for the second time within a session. I was curious and checked if this is also the case with XML Charts. XML Charts did behave the same way if I used IE. It was easy to solve the problem with XML Chart package by adding an additional parameter to the link in form of a random number

v_random := DBMS_RANDOM.random;

After adding this, the problem was not there any more. I think, the same needs to be done with the Flash Charts in ApEx in one of the next releases. Eventually using the same method.

If you want to see a practical example of what I'm talking about, go to my Demo Application

http://apex.oracle.com/pls/otn/f?p=31517:169

and follow these steps:

1. Use IE (Internet Explorer),

2. Make sure your Internet Options / Browsing History / Settings is either set to "automatically" or "never",

3. Make a round trip and click all three pie slices of the pie chart showing departments,

4. After you click on any of the slices for the second time, the second flash chart will not show you the right result but will remain the same all the time.

5. You will need to submit the page in order to get the values change.

And now, the best thing is that the XML Chart will always show the right values. Even if the IE settings Internet Options / Browsing History / Settings are set to "never".

ApEx Item - Workarround

There may be some cases where you need to use apex_item (although, Patrick Wolf doesn't think so). The downside of that approach is:

1. your Query looks awkward,

2. you can't sort on your columns,

3. you can't display your column totals

In case you didn't know, you may use a trick to work around that problem:

a) crate a normal query like this:

SELECT LPAD (ROWNUM, 4, 0) ROW_NUM, deptno, empno, ename, 
       sal, comm
  FROM emp

b) In the HTML expression of your columns put the following for each column accordingly:

<input id="f03_#ROW_NUM#" type="text" style="text-align: right;" 
value="#EMPNO#" maxlength="4" size="4" name="f03"/>

c) You may use the items in your custom update process and in your javascript the same way you do when you use apex_item or the wizard generated table.

Now, you may create column totals and sort on such created items. And your SQL query looks much better.

As always, there is a proof of concept in my Demo Application on this page http://htmldb.oracle.com/pls/otn/f?p=31517:168.

By the way. Around 100 people from all over the globe asked and received a personal account for the Demo Application. If you are also interested to look behind the curtains, please feel free to send me an email with your contact details.

Sorting on apex_item

If you use apex_item syntax in your query, you will not be able to sort on the columns in a way you would expect because ApEx will sort the column on the string you use as input. This means it will sort on something like

<input id="f04_9" type="text" style="text-align: right;" value="2300" maxlength="12" size="12" name="f04"/>

To overcome this problem you may want to use the following in front of your apex_item:

'<INPUT TYPE="HIDDEN" VALUE="'
|| LPAD (sal, 20, '0')
|| '" />'
|| apex_item.text (4,
TO_CHAR (sal),
12,
12,
'style="text-align:right" ',
'f04_' || ROWNUM,
NULL
) sal_editable



You could use any other value instead of the original one as well (ROWNUM, ename) and use it for sorting.

Here, you will find a working example:

http://htmldb.oracle.com/pls/otn/f?p=31517:167

Enjoy.

Filtering a Shuttle Item

Very often a shuttle item is much convenient than a multiselect list. But what if your LOV has many hundreds or even thousands of items? Check this example:

http://htmldb.oracle.com/pls/otn/f?p=31517:166



The most of the code can be reused except of the application process. However, this
could be written as a dynamic PL/SQL block as well.

The example I used is based on a table containing around 5000 records. Having in mind this runs on apex.oracle.com, the performance of filtering is quite satisfying.

Report with Filtering

As far as I know, something similar should be a part of the ApEx version 3.1. Nevertheless, I wanted to know if I can do something like that myself. The requirement is:

1. a report containing a search field for each column (textfield, select list or other)

2. after typing in the select criteria, the report should filter the results,

3. no page submit required.

Here is the result of what I came up with. It is quite easy (and dirty). There, you will also find the full code I used, except of the DHTML Region Pull. That one, you can find in the Carl's Demo Application.



The downsides of this example:

a) the code is not generic - you got to do that yourself ;)

b) the sorting on the column headers doesn't work in that particular example - I avoided that since it would mean a much more work.

Maybe, you will find it usefull and apply it on one or the other case.

ApEx Training

This posting is targeting the German ApEx comunity and is therefor posted in German language:

Wie Sie möglicherweise schon gehört haben, organisieren Patrick, Dietmar und ich einen ApEx Training im März dieses Jahres. Dieses Training heisst "Fortgeschrittene Techniken aus der Praxis". Das bedeutet natürlich nicht, dass diejenigen, die sich anmelden wollen, fortgeschrittene Kentnisse mitbringen müssen. Vielmehr ist unser Ziel, eine Schulung zu organisieren, die stärker praxisorientiert ist als wir das ansonsten kennen. Wir werden viele wichtige Themen ansprechen - vom Anwendungskonzept, über Layout bis zu den ganz modernen Themen wie z.B. Ajax. Interesse? Ueber dieses Link geht es zu den Infos und zur Anmeldung

http://www.opal-consulting.de


Wir freuen uns Sie begruessen zu duerfen!

Tabular form - updating a value in another column Vol. 2

If you need to deal with a tabular form created by the wizard, you will need to use a slightly different approach. I discussed that topic yesterday evening with Patrick Wolf. The difference to the first approach you can find here:

ApEx Demo Appication - Javascript Set Display Item II.

The full explanation and the code are there as well. Basically, what you need to change is the way you get the rownum. Using $x(this).id will give you the current item id. Substr(4) will give you the last four digits of it (thanks Patrick) and putting that four digits in the Number() function gives you the row number (ROWNUM). You could use that value to loop through the table and update other values, not corresponding to that particular row.

Access to my Workspace

My workspace dkubicek and my ApEx Demo Application on apex.oracle.com still show around 3000 page clicks per day in average. Google Analytics says there are up to 300 visitors with an average time on site of 11 minutes. 30% of the visitors are visiting the site for the first time.

Yesterday, I changed the login for the guest user in my workspace. In the past I was allowing access to my workspace with the same login as well. However, this showed to be a bad practice. Once, the application was deleted by someone and I needed my backup to restore it. Now, I require your email and your full name to give you your own access. But, I still need to ask you not to do any changes and especially not to install other applications in my workspace.



If you want an access to the workspace where the ApEx Demo Application is stored, please send me your email with your contact details and I will respond to you with a username and a password.



 

Tabular form - updating a value in another column Vol. 1

Just recently, I had a requirement from one of my customers to create a kind of a form similar to excel, where user could update particular columns and this update will be applied (calculated) to the other columns, before the form is submitted.

First, I tried the solution posted in the forum, where you need to loop through a table using html_CascadeUpTill and and then find the row position. In some constelations this didn't work (vertical report template). I decided to look for alternate solutions and found out that this can be done in a more transparent way by simply using apex_item package and the ROWNUM. Also, the javascript code you need to do the update is much more transparent and much easier to debug. I also created a validation process to make sure only numbers are entered and an update statement for saving the changes to the corresponding table.

If you want to see a working example, go to my ApEx Demo Appication. There, you will find the full code.

ApEx Stammtisch - ApEx Meeting in Siegburg

Dietmar and myself would like to establish regular meetings for the ApEx community in Germany. Therefor, we will start with our first meeting ("Stammtisch" in German) in Siegburg, on January 15, 2008. The target is to exchange the experience with other colleagues from the ApEx community. Further details you can find here:

http://www.opal-consulting.de

You are welcome to join us,

Denes

-----------------------------------------------------------------------------------------------------------------

Es war Dietmars Idee, einen sog. ApEx Stammtisch zu etablieren! Er hat sie am Ende auch umgesetzt (Danke Dietmar!). Wir starten am 15.01.2008 in Siegburg. Der Plan ist diese Runde in regelmässigen Abständen zu organisieren, um die Erfahrungen aus der ApEx-Welt auszutauschen. Die Anmeldung zum Stammtisch findet ihr hier:

http://www.opal-consulting.de

Wir freuen uns auf ein Kennenlernen und bis zum nächsten Dienstag.

Denes

Create Virtual Tables Vol.2

Every once in a while a question similar to this one will appear in the forum. The problem is always the same: "how to create a lot of data based on very few records?". Today, one new variation of a puzzle followed. It took me arround half an hour in order to create a demo page, giving an idea on how to solve the problem. Of course, you need much more for a working version of an application.





The example in my demo application


http://htmldb.oracle.com/pls/otn/f?p=31517:158


is related to one of the examples from the past


http://htmldb.oracle.com/pls/otn/f?p=31517:83


which I already blogged about here


http://deneskubicek.blogspot.com/2007/05/create-pseudo-tables.html


Still, this requirement is somewhat new and different. It is worth of looking into it.