Plug & play tabular form handling

12. December 2006

I still remember the time when I was an APEX newbie and I really got confused with tabular forms (updateable reports). They behaved very different from what I knew about “normal” page items. So what where the issues which confused me?

It isn’t possible to create any validations on the columns of the report, like I can do it for page items.
You have to use the APEX_Application.g_fxx arrays instead of using bind variables as for page items.
To find the correct array you have to look into the generated HTML code for the correct mapping.
If the order of the columns gets changed, your code gets screwed up, because the columns now maps to a different g_fxx array.
If a column has a condition or authorization the g_fxx array changes again, in the case the column doesn’t get rendered.
The code isn’t really readable if there are just references to g_f01, g_f02, …
The format mask has to be duplicated if the g_fxx is accessed and you want to get the correct data type (eg NUMBER, DATE)
When you want to get the number of array entries you have to take care that you don’t use the array for a checkbox column, because that just contains the checked values!
You have no function to find out if the row has changed.
When the validation of a format mask or required column fails, the error message is very internal. The user doesn’t have a clue which column and which row was effected. And it stops after the first error.

That’s a long list and that’s why I did some programming on the weekend to get a solution for the above short comings, so that newbies and experienced APEX developers don’t have to care anymore.

To make a long story short, I have created a package which you just call once in your application and which takes care of the above problems. It allows you to

reference your columns by name without having to hassling around to which array your column is mapped.
To get the correct number of rows to process
Identify which row has changed
Get your data with the correct data type (NUMBER, DATE) without having to take care about format masks.
Add a required column check by declaration, instead of coding it.
Get more meaningfull error message than APEX provides.

But first try it by yourself, I have set up a tabular form with the default APEX handling for tabular forms. Follow the instructions and play around with it.

Standard Tabular Form example

After you have done that, check out my

Enhanced Tabular Form example.

How to integrate it into your application?

Follow the steps in my How to integrate posting.

In the case if you don’t want that one of your report regions is processed by the library, add $APEXLIB_IGNORE_VALIDATION$ in the region comment to skip the processing.

That’s the basic integration which does the required column and format mask check. If you want to access your column in your own validation code, follow the example to see how to do that.

Example

Create a new page
- Page Type: Form/Tabular Form
- Allowed Operations: Update, Insert and Delete
- Table / View Name: EMPLOYEES
- Select Columns(s): Everything except of PHONE_NUMBER, COMMISSION_PCT, MANAGER_ID and DEPARTMENT_ID
- Primary Key Column1: EMPLOYEE_ID
- Source Type: Existing trigger
- Updateable Columns: ALL
- Confirm everything on the following pages
Open the Report Attributes of the created region.
- For the columns LAST_NAME, EMAIL, HIRE_DATE, JOB_ID go to the Column Link section and enter $APEXLIB_REQUIRED$ as Link Attributes
- For the column HIRE_DATE set the following properties
  - Display As: “Date Picker”
  - Date Picker Format Mask: “DD-MM-YYYY” => we use a different format mask than the database has, so that auto date convertion doesn’t work!
  - Element Width: 10
- For the column JOB_ID set the following properties
  - Display As: Select List (query based LOV)
  - LOV Query:
```
SELECT JOB_TITLE AS D, JOB_ID AS R FROM JOBS ORDER BY JOB_TITLE
```
- For the column SALARY set the following properties
  - Number / Date Format: FML999G990D00

Let’s create some extra validation, so that you see how easy it is to access your columns. Create a validation for the created page

Identify the validation level: Page level validation
Select a validation method: PL/SQL
Select the type of PL/SQL validation you wish to create: Function Returning Error Text
Sequence: 10
Validation Name: Validate Hire Date and Salary
Error Display Location: On Error Page

Validation:

DECLARE
    vMinSalary NUMBER;
    vMaxSalary NUMBER;
BEGIN
    FOR ii IN 1 .. ApexLib_TabForm.getRowCount
    LOOP
       IF ApexLib_TabForm.hasRowChanged(ii)
       THEN
           IF ApexLib_TabForm.DV('HIRE_DATE', ii) > SYSDATE
           THEN
               ApexLib_Error.addError
                 ( pError      => 'Hire Date is in the future'
                 , pColumnName => 'HIRE_DATE'
                 , pRow        => ii
                 );
           END IF;
           --
           SELECT MIN_SALARY
                , MAX_SALARY
             INTO vMinSalary
                , vMaxSalary
             FROM JOBS
            WHERE JOB_ID = ApexLib_TabForm.V('JOB_ID', ii)
           ;
           IF ApexLib_TabForm.NV('SALARY', ii) NOT BETWEEN vMinSalary AND vMaxSalary
           THEN
               ApexLib_Error.addError
                 ( pError      => 'Salary has to be between %0 and %1'
                 , pColumnName => 'SALARY'
                 , pRow        => ii
                 , p0          => vMinSalary
                 , p1          => vMaxSalary
                 );
           END IF;
       END IF;
    END LOOP;
    --
    RETURN ApexLib_Error.getErrorStack;
END;

Error Message: Error occurred.

As you can see in the code, you don’t have to care about date convertion, you are only processing the changed records. The code is still understandable when you look at the code 5 days later, aren’t names more meaningful than just references
to APEX_Application.g_f01?

You have different getter functions to access your columns. ApexLib_TabForm.V, -NV and -DV have the same purpose as the existing APEX functions which you can use for items. Check out the package specification of the ApexLib_TabForm package, all the functions are documented.

BTW, if you are not satisfied with the error message the validateColumns procedure is raising for required and format mask check. You can define your own error text by creating a message (Shared Components/Text Messages). The name has to be APEXLIB_TABFORM_COLUMN_REQUIRED (Format: Column “%0″ is required.) or APEXLIB_TABFORM_INVALID_FORMAT (Format: Column value of “%0″ doesn’t match to the format “%1″.) The row prefix can be define with APEXLIB_TABFORM_ROW_PREFIX (Format: Row %0: ).

Impact on your existing application

Nothing really changes except that you have better error messages in your tabular form, so it’s no problem to use it also for your existing application.

Update

Check out the Accessing the row selector of a tabular form for an example how you can access the row selector.
Check out Hacking the APEX error page to display the errors as inline message.
Check out Hacking the APEX error page – Part 2 to highlight the column cells which have an error.

Known restrictions

If you use APEX_Item or HTMLDB_Item to build your own form elements. I can’t map the columns, because I don’t know which index you have used.
If a column has a condition or authorization. See below.

Problems?

Enable debugging, it will show you what the library is doing and which columns are mapped to which array. Look for ApexLib_TabForm in the output.

What’s next?

I have now a question. Where do you install the packages? Are you allowed to install them into the FLOWS schema? Because that would make the condition checking a breeze. If there is a big demand to just install the packages into the application schema, I have to re-code the condition/authorization checking, because it’s not accessable from the application schema.

Do you have other ideas and troubles with tabular form handling which you want to automate? Feedback very welcome!

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22 Responses to “Plug & play tabular form handling”

Andree Says:
December 19th, 2006 at 05:36

Hello Patrick,

first of all THANK YOU for your work. I always hated it to look at the HTML-Code to find out the right g_fxx number! Let’s say it’s a dark past now! But I cannot get the whole stuff to work. I tried your complete example in

http://inside-apex.blogspot.com/2006/12/plug-play-tabular-form-handling.html

but when detecting an input error with the page validation process APEX shows me this usual ugly error page with the red stop sign but with the error message I created in the page process. (Rather than above the report area) I followed your example by creating the application process and by inserting $APEXLIB_REQUIRED$ as link attributes.
I tried it on APEX Express 2.1.

Some hint for me ?
Thanks
Andree

Patrick Wolf Says:
December 19th, 2006 at 06:12

Hi Andree,

sorry my example page also already incorporates my APEX error page hack (http://inside-apex.blogspot.com/2006/12/hacking-apex-error-page.html).

That’s why the error message is displayed above the report region.

BTW, I’m currently working on some additions to highlight the column cell which has an error. Stay tuned.

Patrick

Andree Says:
December 19th, 2006 at 23:17

Hello Patrick,

nice enhancement !
One minor thing:
You forgot to add the grant and synonym for APEX_LIB_ERROR in the HowtoInstall.txt.

Thanks again!
Andree

Andree Says:
December 19th, 2006 at 23:39

… and once again hello !

Now I have some more issues to ask for…
(1)
I have two columns to check. According to your example I coded both checks with separate calls to ApexLib_Error.addError and at the end of the validation i called RETURN ApexLib_Error.getErrorStack.
When I start the page I have in one row for any reason an (old) error condition in the first of the two columns. This error is not detected when submited AND THAT IS OK, because the row contents did not change. BUT when I change the contents of the second column of the same row (to a correct or wrong value) the (unchanged) error of the first column is detected. Seems not logical.
(2)
You force “Row xx:” in front of the error message. How can I change or suppress it ? Seems not reasonable for a german (or other language than english) application.
(3)
You force a “f0x_000y” at the end of the message. Is it a forgotten debug output or did I something wrong ?

Thank you again ! It’s a really great help to use your tools !
Keep going on !
Andree

Patrick Wolf Says:
December 19th, 2006 at 23:41

Hi Andree,

thanks a lot for letting me know! I have already fixed it and uploaded release V0.12.

So you are installing it in the FLOWS schema? No problems with your DBA?

Patrick

Patrick Wolf Says:
December 19th, 2006 at 23:56

Ups, another comment

1) I can’t really detect if a single column value has changed, because APEX is just generating a checksum for the hole record. But anyway, when you write an IF and read the value of a column, how should the library know that you don’t want to check this column, because it hasn’t changed? Or do you mean the automatic required and format mask check?

But as I said, single column change detection will not be possible as long as I’m not reading the record from the database… Costs performance…

2) All the messages the ApexLib library is raising can be translated, add under Shared Components\Text Message entries for APEXLIB_TABFORM_ROW_PREFIX, APEXLIB_TABFORM_COLUMN_REQUIRED and APEXLIB_TABFORM_INVALID_FORMAT. Details about the format and placeholders can be found in the posting.

3) You see that f0x_000y in your error message? Or only when you are running in debug mode? Or do you also see it in the inplace message? The user normally should see it as long as he is running in debug mode.

Great that you are really using it! That’s the way to find bugs the fastest way.

Patrick

Andree Says:
December 20th, 2006 at 00:19

Hello Patrick,

Yes, I installed it, because for the Express Edition on my own machine I AM THE DBA (Hugh!).

1) I guessed that!
2) Works !
3) Until now I did not install the “error page hack” and live with the usual page with the red sign. And there the messages are concatinated with “f0x_000y” (x and y depending on column and row) No debug mode. (APEX Task bar shows “Debug” NOT “No Debug”, so it is switched off)
If you give me an email address, I send you a screenshot.

Regards
Andree

Patrick Wolf Says:
December 20th, 2006 at 01:34

Ok, in the case if you are not using the APEX error page hack yet, it’s clear for me why you see it.

But if you are not using it, your columns cell will never get highlighted! If you don’t like to use the highlighting, you can call the addError with pColumnName => NULL, pRow => NULL. So that the column information isn’t added to the error message.

But I will add something into the next version so that this information is always hidden.

You can find my e-mail address in the profile of the blog.

Patrick

Fury Says:
June 15th, 2007 at 08:56

Hi Patrick,

(Beginner level)

I was using the Tabular Form and I found a problem. What can I do to validate this?: if I erase a value from a field and then click on the Submit button. After this an error appears “Error in mru internal routine: ORA-20001: Error in MRU: row= 1, ORA-01407: cannot update (”SUPPORT”.”GK_ACCESS_TYPES”.”ACCESS_TYPE_DESC”) to NULL, update “SUPPORT”.”GK_ACCESS_TYPES” set “ACCESS_TYPE_ID” = :b1, “ACCESS_TYPE_DESC” = :b2 where “ACCESS_TYPE_ID” = :p_pk_col
“.

How can I fix this exception?

Fury Says:
June 15th, 2007 at 09:36

btw, in my previous comment, that error is displayed when the submit button tries to do an update into a table, but it tries to update a field with a null value… and I want to display a normal error message not that exception page

thank you

Patrick Wolf Says:
June 15th, 2007 at 13:27

Hi Fury,

if you are using my ApexLib Framework, just use the $APEXLIB_REQUIRED$ tag to tell the framework that the column is required and it will do all necessary checks that the tabular form column contains a value.

See above for further details.

Patrick

Terence Lee Says:
January 21st, 2009 at 03:19

Hi Patrick,

You have done a good job on creating this APEXLIB framework to make our life easier for APEX development. But I have encountered a problem that the APEXLIB_TABFORM functions (like getRowCount, hasRowChanged) will not return proper value if the report region has a condition there. Once I remove the condition for the region, the APEXLIB_TABFORM will be able to return the correct value. Is there any solution for this?

Thanks.

Best Regards,
Terence

Patrick Wolf Says:
January 21st, 2009 at 09:32

Hi Terence,

that’s a restriction of the current implementation of the ApexLib_Tabform package which is probably removed in a future version – it’s not so easy

Patrick

Aashu Says:
February 5th, 2009 at 11:39

Hi Patrick,

I put a validation on the two select list in tabular form by using g_f01,but this is not working until and unless i will not check the corresponding check box,then I saw your enhancement here and tried with your suggested way i.e by using APEXLIB_TABFORM,but got error :
‘identifier ‘APEXLIB_TABFORM.GETROWCOUNT’ must be declared’
Am I doing something wrong?
Please suggest.

Patrick Wolf Says:
February 6th, 2009 at 10:13

Hi Aashu,

have you installed the ApexLib Framework? You can find it at http://apexlib.oracleapex.info/

Regards
Patrick

Miguel Arriaga Says:
March 4th, 2009 at 18:19

Patrick, thanks for your help.

I have a problem workink with tabular forms, can I have a tabular form based on a view, in fact a complex view, and update 2 fields of the view?

I’m going crazy, because I try to do this and only get the following error:

Error in mru internal routine: ORA-20001: no data found in tabular form
Error Unable to process update.
OK

Patrick Wolf Says:
March 4th, 2009 at 23:20

Hi Miguel,

are you using apex_item or htmldb_item in your SQL statement of the report?

Can you put an example on apex.oracle.com?

Patrick

Bert Says:
March 23rd, 2009 at 10:30

Patrick,

I want substitute the g_fxx with a usefull name, but i can’t find an example. The error handling works perfect with e.g. “ApexLib_TabForm.NV(’SALARY’, ii)”.
But this is a IF statement.

How can i change
—————–
FOR ii IN 1 .. APEX_Application.g_f04.COUNT
LOOP
APEX_Application.g_f04(ii) := ‘N’;
END LOOP;
—————-
where g_f04 is SALARY.

Thanks for answering.

Bert

Aşkın Says:
June 26th, 2009 at 13:43

Hi,

I did above example. Everything worked fine.(Apex 3.2)

But Error messages don’t come above the tabular form.

I debuged error messages come to error page not tabular form page.

I tried to understand the code. If I am not wrong these error messages are transfered to tabular form page by cookies. My browser blocks such cookies.

Is there any solution for this?

Thanks for everthing

Bonnie Says:
September 2nd, 2009 at 21:52

Hi Patrick,
Can your tabular form solution allow me the ability to access a
column value in the row, to use in the LOV query of another column in the row? I need a dynamic LOV in my Tabular Form.

Thanks.

Bonnie
(New to Apex)

Knut Says:
November 6th, 2009 at 11:30

Hi Patrick,

It’s a really great enhancement, but I have a big question:
“When will it be possible to have a condition on a region/item and use your Framework?”
Or how it is possible to hide a column of a table without using a condition?

Best Regards,
Knut

Peter Raganitsch Says:
December 14th, 2009 at 12:40

Hi Knut,

i’m planning to add some basic condition support for the next release of Apexlib (2.1).

In the meantime you can hide columns of a table using javascript (preferably jQuery).

Peter

Andree Says:
December 19th, 2006 at 05:36
Hello Patrick,

first of all THANK YOU for your work. I always hated it to look at the HTML-Code to find out the right g_fxx number! Let’s say it’s a dark past now! But I cannot get the whole stuff to work. I tried your complete example in

http://inside-apex.blogspot.com/2006/12/plug-play-tabular-form-handling.html

but when detecting an input error with the page validation process APEX shows me this usual ugly error page with the red stop sign but with the error message I created in the page process. (Rather than above the report area) I followed your example by creating the application process and by inserting $APEXLIB_REQUIRED$ as link attributes.
I tried it on APEX Express 2.1.

Some hint for me ?
Thanks
Andree
Patrick Wolf Says:
December 19th, 2006 at 06:12
Hi Andree,

sorry my example page also already incorporates my APEX error page hack (http://inside-apex.blogspot.com/2006/12/hacking-apex-error-page.html).

That’s why the error message is displayed above the report region.

BTW, I’m currently working on some additions to highlight the column cell which has an error. Stay tuned.

Patrick
Andree Says:
December 19th, 2006 at 23:17
Hello Patrick,

nice enhancement !
One minor thing:
You forgot to add the grant and synonym for APEX_LIB_ERROR in the HowtoInstall.txt.

Thanks again!
Andree
Andree Says:
December 19th, 2006 at 23:39
… and once again hello !

Now I have some more issues to ask for…
(1)
I have two columns to check. According to your example I coded both checks with separate calls to ApexLib_Error.addError and at the end of the validation i called RETURN ApexLib_Error.getErrorStack.
When I start the page I have in one row for any reason an (old) error condition in the first of the two columns. This error is not detected when submited AND THAT IS OK, because the row contents did not change. BUT when I change the contents of the second column of the same row (to a correct or wrong value) the (unchanged) error of the first column is detected. Seems not logical.
(2)
You force “Row xx:” in front of the error message. How can I change or suppress it ? Seems not reasonable for a german (or other language than english) application.
(3)
You force a “f0x_000y” at the end of the message. Is it a forgotten debug output or did I something wrong ?

Thank you again ! It’s a really great help to use your tools !
Keep going on !
Andree
Patrick Wolf Says:
December 19th, 2006 at 23:41
Hi Andree,

thanks a lot for letting me know! I have already fixed it and uploaded release V0.12.

So you are installing it in the FLOWS schema? No problems with your DBA?

Patrick
Patrick Wolf Says:
December 19th, 2006 at 23:56
Ups, another comment

1) I can’t really detect if a single column value has changed, because APEX is just generating a checksum for the hole record. But anyway, when you write an IF and read the value of a column, how should the library know that you don’t want to check this column, because it hasn’t changed? Or do you mean the automatic required and format mask check?

But as I said, single column change detection will not be possible as long as I’m not reading the record from the database… Costs performance…

2) All the messages the ApexLib library is raising can be translated, add under Shared Components\Text Message entries for APEXLIB_TABFORM_ROW_PREFIX, APEXLIB_TABFORM_COLUMN_REQUIRED and APEXLIB_TABFORM_INVALID_FORMAT. Details about the format and placeholders can be found in the posting.

3) You see that f0x_000y in your error message? Or only when you are running in debug mode? Or do you also see it in the inplace message? The user normally should see it as long as he is running in debug mode.

Great that you are really using it! That’s the way to find bugs the fastest way.

Patrick
Andree Says:
December 20th, 2006 at 00:19
Hello Patrick,

Yes, I installed it, because for the Express Edition on my own machine I AM THE DBA (Hugh!).

1) I guessed that!
2) Works !
3) Until now I did not install the “error page hack” and live with the usual page with the red sign. And there the messages are concatinated with “f0x_000y” (x and y depending on column and row) No debug mode. (APEX Task bar shows “Debug” NOT “No Debug”, so it is switched off)
If you give me an email address, I send you a screenshot.

Regards
Andree
Patrick Wolf Says:
December 20th, 2006 at 01:34
Ok, in the case if you are not using the APEX error page hack yet, it’s clear for me why you see it.

But if you are not using it, your columns cell will never get highlighted! If you don’t like to use the highlighting, you can call the addError with pColumnName => NULL, pRow => NULL. So that the column information isn’t added to the error message.

But I will add something into the next version so that this information is always hidden.

You can find my e-mail address in the profile of the blog.

Patrick
Fury Says:
June 15th, 2007 at 08:56
Hi Patrick,

(Beginner level)

I was using the Tabular Form and I found a problem. What can I do to validate this?: if I erase a value from a field and then click on the Submit button. After this an error appears “Error in mru internal routine: ORA-20001: Error in MRU: row= 1, ORA-01407: cannot update (”SUPPORT”.”GK_ACCESS_TYPES”.”ACCESS_TYPE_DESC”) to NULL, update “SUPPORT”.”GK_ACCESS_TYPES” set “ACCESS_TYPE_ID” = :b1, “ACCESS_TYPE_DESC” = :b2 where “ACCESS_TYPE_ID” = :p_pk_col
“.

How can I fix this exception?
Fury Says:
June 15th, 2007 at 09:36
btw, in my previous comment, that error is displayed when the submit button tries to do an update into a table, but it tries to update a field with a null value… and I want to display a normal error message not that exception page

thank you
Patrick Wolf Says:
June 15th, 2007 at 13:27
Hi Fury,

if you are using my ApexLib Framework, just use the $APEXLIB_REQUIRED$ tag to tell the framework that the column is required and it will do all necessary checks that the tabular form column contains a value.

See above for further details.

Patrick
Terence Lee Says:
January 21st, 2009 at 03:19
Hi Patrick,

You have done a good job on creating this APEXLIB framework to make our life easier for APEX development. But I have encountered a problem that the APEXLIB_TABFORM functions (like getRowCount, hasRowChanged) will not return proper value if the report region has a condition there. Once I remove the condition for the region, the APEXLIB_TABFORM will be able to return the correct value. Is there any solution for this?

Thanks.

Best Regards,
Terence
Patrick Wolf Says:
January 21st, 2009 at 09:32
Hi Terence,

that’s a restriction of the current implementation of the ApexLib_Tabform package which is probably removed in a future version – it’s not so easy

Patrick
Aashu Says:
February 5th, 2009 at 11:39
Hi Patrick,

I put a validation on the two select list in tabular form by using g_f01,but this is not working until and unless i will not check the corresponding check box,then I saw your enhancement here and tried with your suggested way i.e by using APEXLIB_TABFORM,but got error :
‘identifier ‘APEXLIB_TABFORM.GETROWCOUNT’ must be declared’
Am I doing something wrong?
Please suggest.
Patrick Wolf Says:
February 6th, 2009 at 10:13
Hi Aashu,

have you installed the ApexLib Framework? You can find it at http://apexlib.oracleapex.info/

Regards
Patrick
Miguel Arriaga Says:
March 4th, 2009 at 18:19
Patrick, thanks for your help.

I have a problem workink with tabular forms, can I have a tabular form based on a view, in fact a complex view, and update 2 fields of the view?

I’m going crazy, because I try to do this and only get the following error:

Error in mru internal routine: ORA-20001: no data found in tabular form
Error Unable to process update.
OK
Patrick Wolf Says:
March 4th, 2009 at 23:20
Hi Miguel,

are you using apex_item or htmldb_item in your SQL statement of the report?

Can you put an example on apex.oracle.com?

Patrick
Bert Says:
March 23rd, 2009 at 10:30
Patrick,

I want substitute the g_fxx with a usefull name, but i can’t find an example. The error handling works perfect with e.g. “ApexLib_TabForm.NV(’SALARY’, ii)”.
But this is a IF statement.

How can i change
—————–
FOR ii IN 1 .. APEX_Application.g_f04.COUNT
LOOP
APEX_Application.g_f04(ii) := ‘N’;
END LOOP;
—————-
where g_f04 is SALARY.

Thanks for answering.

Bert
Aşkın Says:
June 26th, 2009 at 13:43
Hi,

I did above example. Everything worked fine.(Apex 3.2)

But Error messages don’t come above the tabular form.

I debuged error messages come to error page not tabular form page.

I tried to understand the code. If I am not wrong these error messages are transfered to tabular form page by cookies. My browser blocks such cookies.

Is there any solution for this?

Thanks for everthing
Bonnie Says:
September 2nd, 2009 at 21:52
Hi Patrick,
Can your tabular form solution allow me the ability to access a
column value in the row, to use in the LOV query of another column in the row? I need a dynamic LOV in my Tabular Form.

Thanks.

Bonnie
(New to Apex)
Knut Says:
November 6th, 2009 at 11:30
Hi Patrick,

It’s a really great enhancement, but I have a big question:
“When will it be possible to have a condition on a region/item and use your Framework?”
Or how it is possible to hide a column of a table without using a condition?

Best Regards,
Knut
Peter Raganitsch Says:
December 14th, 2009 at 12:40
Hi Knut,

i’m planning to add some basic condition support for the next release of Apexlib (2.1).

In the meantime you can hide columns of a table using javascript (preferably jQuery).

Peter

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Inside Oracle APEX by Patrick Wolf