CODEWITHSUNDEEP
pythonkivykivy-languagekivymd
eljamba
eljamba

Reputation: 385

Kivy/KivyMD: Add a method when the selection of a drop down item changes

I developed an UI with Kivy / KivyMD with Python. The UI is very simple: when a button is pressed a DropDownItem is added to the layout. I need to add a method that is called every time the selection of the DropDownItem changes. Here is the code:

from kivy.lang import Builder
from kivymd.app import MDApp
from kivymd.uix.screen import MDScreen
from kivymd.toast import toast
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.dropdownitem.dropdownitem import MDDropDownItem
from kivy.metrics import dp



Builder.load_string(
    """    
<View>:
    MDGridLayout:
        rows: 3
        id: layout
        padding: 100, 50, 100, 50
        spacing: 0, 50
        
        
        MDRaisedButton:
            text: 'CREATE DDI'
            on_release: root.Button_CreateDDI__On_Click()
            
        MDRaisedButton:
            id: button_check
            disabled: True
            text: 'CHECK SELECTION'
            on_release: root.Button_CheckSelection_On_Click()       

""")



class View(MDScreen):
    def __init__(self, **kwargs):
        super(View, self).__init__(**kwargs)
        
        
    def Button_CreateDDI__On_Click(self):        
        self.myDdi = MDDropDownItem()
        self.myDdi.text = 'SELECT POSITION'
                
        myMenu, scratch = self.Create_DropDown_Widget(self.myDdi, ['POS 1', 'POS 2', 'POS 3'], width=4)
        self.myDdi.on_release = myMenu.open
        self.myDdi.bind(on_select = self.DDI_Selection_Changed)   
        
        
        self.ids.button_check.disabled = False
        self.ids.layout.add_widget(self.myDdi)
        
        
    def Button_CheckSelection_On_Click(self):
        toast('CURRENT VALUE: ' + self.myDdi.current_item)        
        
        
    def DDI_Selection_Changed(self):
        toast('SELECTION CHANGED: ' + self.myDdi.current_item)
        
       
    def Create_DropDown_Widget(self, drop_down_item, item_list, width):
        items_collection = [
            {
                "viewclass": "OneLineListItem",
                "text": item_list[i],
                "height": dp(56),
                "on_release": lambda x = item_list[i]: self.Set_DropDown_Item(drop_down_item, menu, x),
            } for i in range(len(item_list))
        ]
        
        menu = MDDropdownMenu(caller=drop_down_item, items=items_collection, width_mult=width)
        menu.bind()
        
        return menu, items_collection

         
    def Set_DropDown_Item(self, drop_down_item, menu, text_item):
        drop_down_item.set_item(text_item)
        menu.dismiss()
        
        
        

class MainApp(MDApp):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.View = View()


    def build(self):
        self.title = ' DROP DOWN ITEM ADDED DYNAMICALLY'
        return self.View


if __name__ == '__main__':
    MainApp().run()

When the DropDownItem is added in the kv part, you can use the select event. Here the widget is added once the layout is already displayed. So I tried to bind the on_select event, but nothing occured neither an error or an exception. How to call a method everytime the selection of a DropDownItem changes?

Upvotes: 1

Views: 213

Answers (1)

Haw
Haw

Reputation: 31

You already have a function that is invoked whenever an item in the dropdown menu is selected. I would just move the toast there.

def Set_DropDown_Item(self, drop_down_item, menu, text_item):
    drop_down_item.set_item(text_item)
    menu.dismiss()

    toast('CURRENT VALUE: ' + text_item )

Upvotes: 0

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