Blender CollectionProperty / template_list example

colproptest.py

import bpy

bl_info = {
    "name": "CollectionProperty Test",
    "blender": (2,80,0),
    "category": "Test"
}

def _(a=None,b=[]):
    if a:
        b.append(a)
        return a
    else:
        return b

@_
class COLPROPTEST_OT_move(bpy.types.Operator):
    bl_idname = "colproptest.move"
    bl_label = "move"
    index_from: bpy.props.IntProperty(default=-1)
    index_to: bpy.props.IntProperty(default=-1)
    def execute(self,context):
        context.active_object.testitems.move(self.index_from,self.index_to)
        return {"FINISHED"}


@_
class COLPROPTEST_OT_add(bpy.types.Operator):
    bl_idname = "colproptest.add"
    bl_label = "add"
    def execute(self,context):
        ob = context.active_object
        obs = [_.name for _ in context.selected_objects if _ != ob]
        for eachob in obs:
            newitem = ob.testitems.add()
            newitem.name = eachob
        return {"FINISHED"}

@_
class COLPROPTEST_OT_remove(bpy.types.Operator):
    bl_idname = "colproptest.remove"
    bl_label = "remove"
    index: bpy.props.IntProperty(default=-1)
    def execute(self,context):
        context.active_object.testitems.remove(self.index)
        return {"FINISHED"}

@_
class COLPROPTEST_PT_panel(bpy.types.Panel):
    bl_idname = "COLPROPTEST_PT_panel"
    bl_label = "colproptest panel"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "test"
    @classmethod
    def poll(self,context):
        return context.active_object
    def draw(self,context):
        layout = self.layout
        split = layout.split(factor=0.92)
        col1,col2 = split.column(),split.column(align=True)
        ob = context.active_object
        col1.template_list("UI_UL_list","custom_id_blah",
                           ob,"testitems",
                           ob,"testitems_i")
        col2.operator("colproptest.add",text="",icon="ADD")
        col2.operator("colproptest.remove",text="",icon="REMOVE").index = ob.testitems_i
        col2.separator()
        op = col2.operator("colproptest.move",text="",icon="TRIA_UP")
        op.index_from = ob.testitems_i
        op.index_to = ob.testitems_i - 1
        op = col2.operator("colproptest.move",text="",icon="TRIA_DOWN")
        op.index_from = ob.testitems_i
        op.index_to = ob.testitems_i + 1
        if ob.testitems_i > -1:
            active_item = ob.testitems[ob.testitems_i]
            box = layout.box()
            box.label(text=active_item.name)
            box.prop(active_item,"number")


@_
class TestItem(bpy.types.PropertyGroup):
    name: bpy.props.StringProperty()
    label: bpy.props.StringProperty()
    number: bpy.props.IntProperty(default=42)

def register():
    list(map(bpy.utils.register_class,_()))
    bpy.types.Object.testitems = bpy.props.CollectionProperty(type=TestItem)
    bpy.types.Object.testitems_i = bpy.props.IntProperty(min=-1,default=-1)
    
def unregister():
    del bpy.types.Object.testitems_i
    del bpy.types.Object.testitems
    list(map(bpy.utils.unregister_class,_()))