UI Slider as Offset for Array Modifier

Question

I want to create an Addon for a shelf planning tool. The slider should change the offset of the Array Modifier. I already have the slider in my panel, but when I tell the offset to be the slider I always get the message: offset is too short? Even when the slider is 2 for example. How can I change the code to make it work?

import bpy
from bpy.types import Panel, Operator

class RGL_PT_Panel(Panel):
     bl_space_type = "VIEW_3D"
     bl_region_type = "UI"
     bl_label = "Regalplannung"
     bl_category = "Regalplannung"

     def draw(self, context):

         layout = self.layout

         row = layout.row()
         col = row.column()
         col.operator("object.regalplannung", text = "Aufüllen")  
     
         col.prop(context.object, 'Offset_X', text = "Abstand X", 
         slider=True)  
         col.prop(context.object, 'Offset_Y', text = "Abstand Y", 
         slider=True)  

class RGL_OT_regalplannung(Operator):
     """Vollständig gefüllt & Ausrichten"""
     bl_idname = "object.regalplannung"
     bl_label = "Regalplannung"
     bl_description = "Regalplannung in Blender"


     bpy.types.Object.Offset_X = bpy.props.FloatProperty(min = -5, max = 5)
     bpy.types.Object.Offset_Y = bpy.props.FloatProperty(min = -5, max = 5)

     def execute(self, context):

        selection = bpy.context.selected_objects

        for sel in selection:
            
            parent = sel.parent
            parent_0 = parent.dimensions [0]
            parent_1 = parent.dimensions [1]
            parent_2 = parent.dimensions [2]

            mod_array = sel.modifiers.new("Vollständig gefüllt", 'ARRAY')

            mod_array.fit_type = 'FIT_LENGTH'
            mod_array.relative_offset_displace[0] = 0

            if parent_0 < parent_1:
                mod_array.fit_length = parent.dimensions[0] - sel.dimensions[0]    
                mod_array.relative_offset_displace[0] = bpy.types.Object.Offset_X

            else:

                mod_array.fit_length = parent.dimensions[1] - sel.dimensions[1]
                mod_array.relative_offset_displace[1] = bpy.types.Object.Offset_Y
                        
        return {'FINISHED'}
     
bpy.utils.register_class(RGL_PT_Panel)
bpy.utils.register_class(RGL_OT_regalplannung)
```

Answer 1

Your problem is that you are trying to access bpy.types.Object.Offset_X as an object, but that's the type. instead, you need to access sel.Offset_X. You have the same problem with Offset_Y.

The modified code is at lines 51 and 56 in my version.

Here is a version of your script that works, provided I have the selected object parented to another object:

import bpy
from bpy.types import Panel, Operator

class RGL_PT_Panel(Panel):
     bl_space_type = "VIEW_3D"
     bl_region_type = "UI"
     bl_label = "Regalplannung"
     bl_category = "Regalplannung"

     def draw(self, context):

         layout = self.layout

         row = layout.row()
         col = row.column()
         col.operator("object.regalplannung", text = "Aufüllen")  
     
         col.prop(context.object, 'Offset_X', text = "Abstand X", 
         slider=True)  
         col.prop(context.object, 'Offset_Y', text = "Abstand Y", 
         slider=True)  

class RGL_OT_regalplannung(Operator):
     """Vollständig gefüllt & Ausrichten"""
     bl_idname = "object.regalplannung"
     bl_label = "Regalplannung"
     bl_description = "Regalplannung in Blender"


     bpy.types.Object.Offset_X = bpy.props.FloatProperty(min = -5, max = 5)
     bpy.types.Object.Offset_Y = bpy.props.FloatProperty(min = -5, max = 5)

     def execute(self, context):

        selection = bpy.context.selected_objects

        for sel in selection:
            
            parent = sel.parent
            parent_0 = parent.dimensions [0]
            parent_1 = parent.dimensions [1]
            parent_2 = parent.dimensions [2]

            mod_array = sel.modifiers.new("Vollständig gefüllt", 'ARRAY')

            mod_array.fit_type = 'FIT_LENGTH'
            mod_array.relative_offset_displace[0] = 0

            if parent_0 < parent_1:
                mod_array.fit_length = parent.dimensions[0] - sel.dimensions[0]    
                mod_array.relative_offset_displace[0] = sel.Offset_X

            else:

                mod_array.fit_length = parent.dimensions[1] - sel.dimensions[1]
                mod_array.relative_offset_displace[1] = sel.Offset_Y
                        
        return {'FINISHED'}
     
bpy.utils.register_class(RGL_PT_Panel)
bpy.utils.register_class(RGL_OT_regalplannung)
```