Fix for Oracle VBCS "Error 404--Not Found"

We are using Pay As You Go Oracle VBCS instance and had an issue with accessing VBCS home page after starting the service. The service was started successfully, without errors. But when accessing VBCS home page URL - "Error 404--Not Found" was returned.

I raised a support ticket and must say - received the response and help promptly. If you would encounter similar issue yourself, hopefully, this post will share some light.

Apparently "Error 404--Not Found" was returned, because VBCS instance wasn't initialized during instance start. It wasn't initialized, because of expired password for VBCS DB schemas. Yes, you read it right - internal system passwords expire in Cloud too.

Based on the instructions given by Oracle Support, I was able to extract logs from VBCS WebLogic instance (by connecting through SSH to VBCS cloud machine) and provide it to support team (yes, VBCS runs on WebLogic). They found password expire errors in the log, similar to this:

weblogic.application.ModuleException: java.sql.SQLException: ORA-28001: the password has expired

Based on provided instructions, I extracted VBCS DB schema name and connected through SQL developer. Then I executed SQL statement given by support team to reset all VBCS DB passwords in bulk. Next password expiry is set for 2019/January. Should it expire at all?

Summary: If you would encounter "Error 404--Not Found" after starting VBCS instance and trying to access VBCS home page, then most likely (but not always) it will be related to VBCS DB schema password expiry issue.

ADF 12c Table CRUD Fix for Auto Focus

I had a post about how to improve user data entry for ADF table with auto focus for new row - Improving ADF UI Table CRUD Functionality with Auto Focus. If you follow comments thread for that post - you will see described approach doesn't work exactly as it should in ADF 12c (focus is set for new row but later is lost after tab navigation - it should move focus to another column). Thanks to the community we have simple fix for this issue, read OTN Forum thread - Set Focus on CreateINsert row in ADF Table. I hope Oracle will fix this functionality in the next ADF versions (currently they say it is expected behaviour, and I don't agree with this). But for now - fix does the job.

 Sample app was updated to 12.2.1.3 and it contains fixes described on OTN Forum - ADFTableFocusApp_v2.zip. Focus is set for first column of new row to avoid extra mouse click:

After tab is pressed - focus moves to the next column:

Fix simulates row selection through ADF JS API. After focus was set for the first column in current row - we execute row selection based on active row key. This allows ADF Faces to move focus to the next column on tab, because it knows currently selected row on client side:

Make sure to set active row key in the bean method, same place where focus ID is calculated (otherwise there will be JS error):

ADF 12c BC Proxy User DB Connection and Save Point Error

If you are modernising Oracle Forms system, high chance you need to rely on DB proxy connection. Read more about it in my previous post for ADF 11g - Extending Application Module for ADF BC Proxy User DB Connection. It works in the same way for ADF 12c, but there is issue related to handling DB error, when DB proxy connection is on. DB error is propagated to ADF but is being substituted by save point error (as result - user would not see original error from DB). It seems like related to JDBC driver in 12c. The workaround is to override ADF SQL builder class and disable save point error propagation (there might be better ways to workaround it).

Proxy connection is established from prepareSession method in generic AM Impl class:

If I would change salary value to negative and save data - DB constraint error would fire (negative not allowed). Unfortunately, end user would not see that error - he gets message about failed save point:

Workaround -  we can disable save point error propagation. Override SQL Builder class and add try/catch block in rollbackToSavepoint method. If error happens, do nothing:

You must register SQL Builder class with AM. Add jbo.SQLBuilderClass property in bc4j.xcfg, pointing to the class:

You should be able to see DB errors after this change is applied:

However, there is one drawback of this workaround to keep in mind. When data is posted to DB, ADF executes lock statement. If update fails, normally ADF would execute rollback to save point and lock will be removed. But not in the case of DB proxy, now rollback to save point is failing - this means lock will stay:

If user would fix data and try to save again - lock error will be returned:

Error during lock:

To bypass lock issue, you should enable DB pooling for AM instance. In this case, after each request DB connection will be returned back to the pool and lock will be released automatically:

Download sample application - AMExtendApp_v3.zip.

Workaround for ADF BC View Object Attribute Order Problem in JDeveloper 12c

I'm sure probably every ADF developer sooner or later faced this issue. When you create VO based on EO, JDEV gives you alphabetically ordered list of attributes. As a result - order of attributes in EO and VO becomes different. While this doesn't influence runtime functionality, it becomes quite annoying for application maintenance. Hard to match attributes between VO and EO, developer need to search through the list to locate attribute he is looking for. But there is a workaround, I will describe it here.

Let's see what the problem first. Assume we have Employees EO, attributes are generated in the same order as DB table columns:

Now if you are using VO creation wizard, list of attributes will be displayed in alphabetic order. This is frustrating:

Without any other choice, developer would select EO attributes and select them in such order as it is listed:

But wait, there is a workaround. Don't select all attributes, instead select only EO item itself. Then use Add button to add entire list of EO attributes:

This time attributes will be added in original order, as the order is set in EO.

Enjoy this small, but useful hint.

ADF BC REST 12.2.1.2 Custom Method JDeveloper Workaround

Some of you who would try to implement custom method with ADF BC REST may face JDeveloper 12.2.1.2 wizard issue. JDeveloper 12.2.1.2 wizard is refusing to register ADF BC REST custom method, but it works perfectly on ADF runtime. Seems to be JDeveloper 12.2.1.1 - 12.2.1.2 bug. There is a workaround to modify REST service configuration manually and include custom method binding.

Sample application (available on GitHub - jetcrud). This sample implements custom method in VO implementation class - testCall:

Method is exposed through client interface:

Now if you go to REST service definition and try to enable this method to be included into REST interface - JDeveloper will report error:

Something wrong happens in RSTCustomMethodTab class:

Workaround - add method call into REST service definition manually. I recommend to do it outside of JDeveloper, as it hangs. Change definition in external editor. This is the example for custom method entry:

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If you take a look into JDeveloper wizard for REST definition, it still shows method unchecked. But you can ignore it:

To execute custom method through REST call, make sure to use POST and specify method name along with parameters in REST request body:

Make sure not to forget to provide action Content-Type:

Check section for more info - 22.13.5 Executing a Custom Action.

Workaround for ADF 12.2.1.1 Match Media Behavior Tag

If you run ADF 12.2.1.1 application with adaptive UI implemented by af:matchMediaBehavior tag (ADF 12.2.1 Responsive UI Improvements), most likely you will face Null Pointer Exception in Match Media Behavior tag class. Apparently af:matchMediaBehavior tag expects default value to be set on UI component. If default value is not set explicitly, it fails to read it and generates exception (this was not the case in ADF 12.2.1).

This example contains three af:matchMediaBehavior tags, properties orientation and styleClass are not set on panel spitter by default:

This leads into Null Pointer exception on runtime:

To fix this, we can set default values for orientation and styleClass explicitly. Propety styleClass can be assigned with empty value, this helps:

UI is loaded this time:

UI is resized on narrow screen - panel splitter orientation is changed:

Download application with workaround for af:matchMediaBehavior - ADFResponsiveUIApp_v2.zip.

MdsMetadataResourceProvider Error in ADF 11.1.1.7

If you have migrated ADF application to ADF 11.1.1.7 version recently, you may see error in the log related to the internal MetadataResourceXmlImpl class usage. Runtime behaviour will not be affected, but there could be many redundant error messages in the log, like this one:

Error UNEXPECTED_CLIENT_OBJECT_TYPE found oracle.adf.controller.internal.metadata.xml.MetadataResourceXmlImpl, points to the ADF internal class usage, instead of public. You must look through the source code and you should find illegal internal imports for MetadataService and TaskFlowDefinition classes. Typically ADF developer would use such classes in the previous ADF versions to check if specific ADF TF exists:

In ADF 11.1.1.7 you can use public classes for MetadataService and TaskFlowDefinition, instead of private. To fix the error, you only need to change class import:

Here you can download sample application with correct API usage - ADFMetadataInternalApp.zip.

Workaround for ADF 12c Choice List Blank Selection Issue

I would like to share a workaround for Choice List component in ADF 12c. There is specific issue, related to blank selection - as soon as user selects blank selection in the choice list, it starts to invoke value change listener for that list, each time when any other element is selected in the table. This is quite annoying and could lead to unexpected results, especially if you depend on logic implemented in value change listener.

Workaround is implemented in the sample application - ADFChoiceList12cApp.zip. We should take a look first, how it works without workaround applied. Imagine you have a table and one of the columns implements a choice list. Go and select a blank selection for a couple of rows:

Navigate between rows, do couple of clicks - you should notice in the log information about value change listener invoked. This is quite strange, it should not call value change listener each time, just only first time after selection was changed in the list:

Choice list UI component is set with AutoSubmit=true and assigned with value change listener method:

Choice list is configured with blank item selection in ADF BC:

To apply workaround, go and uncheck blank item selection in ADF BC, make sure checkbox for 'Include No Selection Item' is unchecked:

On UI side, provide any value for UnselectedLabel property of the choice list component, this will generate property in the source (alternatively you could just type it manually directly in the source):

Make sure UnselectedLabel property is set to be blank, this will generate blank item on the runtime (it works much better than the one enabled from ADF BC):

User could navigate through the table, there will be no value change listener triggered anymore (besides one time, when value was actually changed):

Exciting as usual - new features and new bugs :)

Handling Format for BigDecimal Numbers in ADF BC

This may not be as straightforward as it sounds - to define a format for a number attribute in ADF BC. Especially if you are going to have large number (more than 15 digits). Most likely you are going to experience precision/scale and rounding issues, for BigDecimal and Number type attributes with format mask applied. Sounds frustrating? Yes it is. I hope my blog post will help you to implement proper number formatting.

Firstly I'm going to demonstrate, how it works by default. I'm going to use format mask for 18 digits and 2 decimals. Format mask for a number attribute of BigDecimal type would fail with invalid precision/scale error - this is surprising, especially knowing that attribute is defined with (20, 2) precision and scale:

There is one more issue to handle - automatic rounding for large numbers (more than 15 digits). In this example I'm trying to enter a number with 18 digits:

Suddenly number is rounded, immediately after focus is moving out of the field - this is bad, user can't enter correct large number:

Let's see, how we can fix it. I will explain solution, based on Salary attribute with (20, 2) precision and scale. By default, this attribute is generated with BigDecimal type, I'm going to keep the same type, no need to change to oracle.jbo.domain.Number:

I have set format mask on the VO level, for the same Salary attribute. There is another issue - maximum length of the attribute value user can enter on UI. Maximum length property is reading precision and calculates maximum number of characters, however this is wrong when format mask is applied:

There will be extra comma and dot signs coming from the format, so I would advice to set Display Width to be equal to the attribute precision plus maximum number of commas and dots (26 in my case). Later we would need to change maximumLength property on the UI to use Display Width instead of precision:

Once you set a format mask, formatter class name is assigned for the attribute. Formatter class name is saved in resource bundle, for each formatted attribute separately:

You must change formatter class name to the custom one, don't use DefaultNumberFormatter class - out of the box formatter doesn't work with BigDecimals. Sample application comes with custom Number formatter class. Format method is overridden to support BigDecimal, standard formatter method breaks BigDecimal number by converting it to Double (this is the reason for rounding error) - this is fixed in the sample:

Method to parse is changed as well (this is fixing precision/scale number for the BigDecimal). Instead of calling parse method from super, I'm calling custom method:

I'm setting a property to enable BigDecimal parsing, this allows to work correctly with precision/scale:

In addition, precision and scale are checked by custom method - if there is invalid number of digits, user will be informed:

I was mentioning it earlier - maximumLength property on the UI is updated to point to Display Width set on the VO attribute UI Hints:

We can do a test now, type long number with 18 digits (remember (20, 2) precision/scale for Salary attribute):

Correct format will be applied:

Type decimal part and now there will be no error about precision/scale - it will be successfully accepted:

You can see from the log how format is being applied, it works well with custom formatter class provided in the sample application - ADFFormattingApp.zip: