LibreOffice Basic: Fixing FilterType Changes With SetFilterFields3

by Viktoria Ivanova 67 views

Hey guys! Ever wrestled with LibreOffice Basic and its quirky behavior when setting up filters in Calc? You're not alone! One common head-scratcher is the FilterType mysteriously changing when you're working with setFilterFields3. Let's break down this issue, explore why it happens, and, most importantly, how to fix it. Buckle up, because we're diving deep into the world of LibreOffice macros!

Understanding the FilterType Fiasco

So, you're diligently crafting your LibreOffice Calc macro, meticulously building a FilterDescriptor to wrangle your data. You've got your theTableFilterFields3 array, packed with TableFilterFields3 objects, each holding an array of FilterFieldValue objects. You're feeling good, almost victorious, until… bam! The FilterType decides to go rogue, changing its value without your explicit permission. Frustrating, right? This usually happens when LibreOffice's internal logic kicks in, attempting to "optimize" or "correct" your filter settings. However, this optimization can sometimes lead to unexpected and unwanted results, especially when dealing with complex filter criteria.

To really grasp what's going on, let's first define some key concepts. The FilterDescriptor is the master control panel for your filter. It holds all the settings, including the filter criteria, the target range, and, crucially, the FilterType. The FilterType itself specifies the kind of filtering you want to perform. Common types include standard filtering, advanced filtering, and filtering based on cell content. The theTableFilterFields3 array is where you define the specific criteria for each column you want to filter. Each element in this array represents a column, and it contains an array of FilterFieldValue objects, which specify the values you want to include (or exclude) in your filter.

The problem often arises when LibreOffice tries to infer the FilterType based on the structure of your theTableFilterFields3 array. For instance, if you provide a simple list of values to filter on in a single column, LibreOffice might assume you want a standard filter. However, if you're using more complex criteria, such as regular expressions or multiple conditions per column, LibreOffice's inference might go awry. This is where the FilterType can change unexpectedly, leading to your filter not working as intended.

Why Does This Happen?

The root cause lies in LibreOffice's attempt to be helpful. It tries to automatically determine the most appropriate FilterType based on the provided filter fields. While this works well in many simple cases, it can become problematic when you're dealing with more intricate filtering scenarios. LibreOffice's automatic FilterType detection sometimes misinterprets your intentions, especially when you're using advanced filtering techniques or custom criteria.

Another factor contributing to this issue is the order in which you set the filter properties. If you set the theTableFilterFields3 array before explicitly setting the FilterType, LibreOffice might jump the gun and try to infer the type before you've had a chance to specify it. This can lead to the FilterType being set to a default value that doesn't match your requirements.

Common Scenarios Where FilterType Changes

  • Using Regular Expressions: If you're using regular expressions in your filter criteria, LibreOffice might not correctly detect this and might default to a standard filter, which doesn't support regular expressions. This will cause your filter to fail or produce incorrect results.
  • Multiple Conditions per Column: When you need to filter a column based on multiple conditions (e.g., values greater than X and less than Y), LibreOffice's automatic FilterType detection can struggle. It might not recognize the need for an advanced filter and might stick with a standard filter, which only allows for simple value matching.
  • Empty Filter Field Arrays: If you have columns in your theTableFilterFields3 array that have empty arrays of FilterFieldValue objects, LibreOffice might misinterpret this as an indication that you don't need a filter, potentially changing the FilterType or even disabling the filter altogether.

Solutions: Taming the FilterType Beast

Okay, enough about the problem! Let's get to the solutions. The key to preventing unwanted FilterType changes is to be explicit and control the filter settings yourself. Here are several strategies you can employ:

1. Explicitly Set the FilterType

This is the most straightforward and reliable solution. Before you set the theTableFilterFields3 array, explicitly set the FilterType in your FilterDescriptor. This tells LibreOffice exactly what kind of filtering you want to perform and prevents it from trying to guess. For advanced filtering, you'll typically want to set the FilterType to com.sun.star.sheet.FilterType.ADVANCED.

Dim oFilterDesc As Object
Dim oTableFilterFields(0) As New com.sun.star.sheet.TableFilterField

oFilterDesc = oSheet.createFilterDescriptor(True)
oFilterDesc.FilterType = com.sun.star.sheet.FilterType.ADVANCED ' Explicitly set the FilterType

' ... (rest of your code to set up theTableFilterFields3) ...

oFilterDesc.setFilterFields3(oTableFilterFields())
oSheet.filter(oFilterDesc)

By explicitly setting the FilterType, you're taking control of the filtering process and ensuring that LibreOffice doesn't make unwanted changes.

2. Set FilterType After Setting Filter Fields (If Necessary)

In some cases, you might find that setting the FilterType before setting the filter fields doesn't completely solve the problem. This can happen if LibreOffice still tries to re-evaluate the FilterType after you've set the fields. If this occurs, try setting the FilterType after you've configured the theTableFilterFields3 array. This gives LibreOffice a chance to see the filter criteria before you lock in the FilterType.

Dim oFilterDesc As Object
Dim oTableFilterFields(0) As New com.sun.star.sheet.TableFilterField

oFilterDesc = oSheet.createFilterDescriptor(True)

' ... (code to set up theTableFilterFields3) ...

oFilterDesc.setFilterFields3(oTableFilterFields())
oFilterDesc.FilterType = com.sun.star.sheet.FilterType.ADVANCED ' Set FilterType after setting filter fields
oSheet.filter(oFilterDesc)

This approach can be particularly useful when you're dealing with complex filter criteria that might confuse LibreOffice's automatic detection.

3. Ensure Consistent Filter Field Structure

Make sure the structure of your theTableFilterFields3 array is consistent and well-defined. If you have columns that you don't want to filter, either exclude them from the array or explicitly set an empty array of FilterFieldValue objects for those columns. Avoid leaving columns undefined or with inconsistent structures, as this can confuse LibreOffice and lead to incorrect FilterType detection.

For example, if you have 5 columns in your data range but only want to filter on columns 1 and 3, make sure your theTableFilterFields3 array has 5 elements. The elements for columns 2, 4, and 5 should either be empty or contain empty arrays of FilterFieldValue objects.

4. Debugging and Logging

When you're facing issues with FilterType changes, debugging and logging can be invaluable tools. Add code to your macro to print the FilterType at various points in your code, such as before and after setting the theTableFilterFields3 array. This will help you pinpoint exactly when the change occurs and what might be triggering it.

Dim oFilterDesc As Object
Dim oTableFilterFields(0) As New com.sun.star.sheet.TableFilterField

oFilterDesc = oSheet.createFilterDescriptor(True)

Print