HOnError (Function)

WINDEV, WEBDEV and WINDEV Mobile propose an automatic management of errors. The automatic management of errors can be disabled or enabled for one or more data files, for one or more types of errors. To do so, use HOnError and specify an empty string for the name of window, page or procedure. For more details, see Assisted HFSQL error handling.

The automatic management of errors is not available for the stored procedures.

Versions 24 and later

HOnError can be used to manage the error in a stored procedure.

New in version 24

HOnError can be used to manage the error in a stored procedure.

Remark: From version 19, HFSQL is the new name of HyperFileSQL.

Versions 17 and later

This function is now available for iPhone/iPad applications.

New in version 17

This function is now available for iPhone/iPad applications.

Versions 18 and later

This function is now available in Windows Store apps mode.

New in version 18

This function is now available in Windows Store apps mode.

Versions 20 and later

This function is now available for Java applications.

This function is now available in Android widget mode.

This function is now available for Android applications.

Onlu the loss of connection can be customized.

New in version 20

This function is now available for Java applications.

This function is now available in Android widget mode.

This function is now available for Android applications.

Onlu the loss of connection can be customized.

This function is now available for Java applications.

This function is now available in Android widget mode.

This function is now available for Android applications.

Onlu the loss of connection can be customized.

Versions 21 and later

This function is now available in Universal Windows 10 App mode.

New in version 21

This function is now available in Universal Windows 10 App mode.

Example

See additional examples

// Define the lock errors
// The OnLockError procedure is called
// when a lock error occurs for all the data files
HOnError("*", hErrLock, "OnLockError")

// Re-enable the automatic management
// of all the errors on all the data files
HOnError("*", hErrAll)

// Re-enable the automatic management
// of lock errors on the Customer data file
HOnError("Customer", hErrLock)

Syntax

<Result> = HOnError(<Data file> , <Type of error> [, <Procedure/window/page>])

<Result>: Boolean

True if the operation was successfully performed,
False otherwise. HError returns more details about the problem.

<Data file>: Character string

Name of the data file used. If this parameter is equal to "*" the customization will be applied to all data files found in the analysis or defined through programming.

<Type of error>: Constant or combination of constants

Type of error to configure.
hErrAll Configure all previous errors (except hErrIndex).
This constant is not available.
hErrConnectionLoss Configure the errors caused by a loss of connection with the HFSQL server.
This constant is not available.
hErrDatabaseAccess Configures the access errors to an HFSQL Client/Server database (access forbidden by HNoDatabaseAccess).
This constant is not available.
hErrDuplicates Configure duplicate errors.
This constant is not available.
hErrIndex Configures indexing errors (reindexing in progress during the file access).
This constant is not available.
hErrIntegrity Configure integrity errors.
This constant is not available.
hErrLock Configure lock errors.
This constant is not available.
hErrModify Configure a modification conflict.
This constant is not available.
hErrNeedValue Configure errors caused by a required value that has not been specified (OLE DB and some Native Connectors).
This constant is not available.
hErrPassword Configure password errors (wrong password).
This constant is not available.

<Procedure/window/page>: Optional character string

Corresponds to:
Name of window or procedure to call when a <Type of error> error occurs.
Name of page or procedure to call when a <Type of error> error occurs.
Name of object method if HOnError is called in a method of this object.
Versions 20 and later
Name of procedure to call when a <Type of error> error occurs.
New in version 20
Name of procedure to call when a <Type of error> error occurs.
Name of procedure to call when a <Type of error> error occurs.
Parameter not specified. If "Enable the automatic HFSQL help" is checked in the project, the default window or page for automatic management of errors is used for the specified type of error and for the specified data file.
Empty string. In this case, the automatic management of errors will be disabled.
Remark: To disable the automatic management of errors, you also have the ability to uncheck "Enable the automatic HFSQL help" in the project.
Remark: In some cases (loss of connection errors for example), the procedure/window/page will be run during the next call to the WLanguage function following the event that triggered the error.
Only some of the windows/pages for the automatic management of errors are available. The automatic management of errors is disabled for these errors.

Special case: using a window, a page or a procedure found in a component: The following syntax must be used:
Procedure:

HOnError(<Data file>, <Type>, ...
"<Component>.<Name of set of procedures>.<Procedure name>")

Window:

HOnError(<Data file>, <Type>, "<Component>.<Window name>")

Page:

HOnError(<Data file>, <Type>, "<Component>.<Page name>")

If a loss of connection occurs, to ask for reconnection, this procedure must call HReconnect.

Remarks

Operating mode of custom errors

The procedure, window or page used to customize the error must return one of the following constants:


opCancel	The function that triggered the error returns an error as if the assisted management was disabled. Remark: For the errors of loss of connection, the error is fatal.
opEndProcess	The function that triggered the error returns an error and the current process stops. Equivalent to the following line of code: IF NOT <HFSQL function> THEN SetFocusAndReturnToUserInput() This constant is not available.
opEndProgram	The function that triggered the error returns an error and the program stops. Equivalent to the following line of code: IF NOT <HFSQL function> THEN EndProgram()
opRelaunchProgram	The program stops and the application is automatically restarted. This constant is not available.
opRetry	The function that triggered the error is re-run.

If a loss of connection occurs, to ask for reconnection, HReconnect must be used in the procedure called by HOnError.

Using a class method to customize the errors

<Name of procedure or window> can also correspond to a method of an object if HOnError is called in a method of this object. All you have to do is specify the name of the method to use (without using the object name as prefix).

A fatal error occurs if the object used in the call to HOnError is no longer allocated when the HFSQL engine calls the method

Customizing the default error windows

The default error windows are supplied (as well as their WLanguage code) for information in the "\Programs\Data\Preset windows\HFSQL - Automatic help windows" directory.

These windows can be customized, included in your projects, and passed as parameters to HOnError.

For more details, see Assisted HFSQL error handling.

Customizing default error pages

The default error pages are supplied (as well as their WLanguage code) for information in the "\Programs\Data\Preset pages\HFSQL - Automatic help pages" directory.

These pages can be customized, included in your projects, and passed as parameters to HOnError.

For more details, see Assisted HFSQL error handling.

Related Examples:

Training (WINDEV): WD Managing HFSQL Errors

[ + ] The "WD Managing HFSQL Errors" example presents the management of HFSQL errors (duplicate, integrity).
This example explains how to customize the process when an error occurs.

Component: wd270hf.dll