Kivy 'object has no attribute' Error

Question

I\'m new to python and Kivy programming so getting trouble and may be asking simple question here, but its a big hurdle for me now. I am developing a GUI with kivy. I have s

Answer 1

Problem

You are getting AttributeError: 'MyLayout' object has no attribute 'print_something' because it cannot find the function, print_something.

Solution

Please refer to the explanations, example and output for details.

Explanations

jwelkreator.py

1. Add from simpleForm import MyLayout
2. Remove Builder.load_file('simpleForm.kv')

jwelkreator.kv

Add #:include simpleForm.kv to include an external kivy file.

include <file> - Kivy Language

Includes an external kivy file. This allows you to split complex widgets into their own files.

simpleForm.py

You don't have to define the dynamic class, LblTxt(BoxLayout) since you have it defined in your kv file.

Dynamic Classes - Programming Guide » Kv language

This class, created just by the declaration of this rule, inherits from the Button class and allows us to change default values and create bindings for all its instances without adding any new code on the Python side.

simpleform.kv

Since in the Python script, simpleForm.py, you have already defined class MyLayout is of BoxLayout, you don't to inherit it in the kv file. Replace <MyLayout@BoxLayout> with <MyLayout>

Example

jwealkreator.py

from kivy.app import App
from kivy.uix.anchorlayout import AnchorLayout
from simpleForm import MyLayout


class JwelKreator(AnchorLayout):
    pass


class JwelKreatorApp(App):

    def build(self):
        return JwelKreator()


if __name__ == "__main__":
    JwelKreatorApp().run()

jwealkreator.kv

# File name: jwelkreator.kv
#:kivy 1.10.0
#:include simpleform.kv

<JwelKreator>:
    anchor_x: 'left'
    anchor_y: 'top'
    MyLayout:
        id: _tool_box
        size_hint: None,0.75
        width: 300

simpleForm.py

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout


class MyLayout(BoxLayout):
    def print_something(self):
        print("Hello")


class SimpleFormApp(App):

    def build(self):
        return MyLayout()


if __name__ == "__main__":
    SimpleFormApp().run()

simpleform.kv

#:kivy 1.10.0

<LblTxt@BoxLayout>:
    id:LblTxtid
    orientation: 'horizontal'
    lblTxtIn: 'default'
    theTxt: iAmTxt
    Label:
        text: root.lblTxtIn
        size_hint: 1,0.5
    TextInput:
        id: iAmTxt
        multiline: False
        hint_text: "numeric only"
        input_filter: 'int'
        size_hint: 0.5,None
        height: 30

<MyLayout>:
    orientation: 'vertical'

    LblTxt:
        id: lt0
        lblTxtIn: 'Base Layers'

    LblTxt:
        id: lt1
        lblTxtIn: 'Base exposer time(ms)'

    LblTxt:
        id: lt2
        lblTxtIn: 'Min Support Height(mm)'

    LblTxt:
        id: lt3
        lblTxtIn: 'Support Layers'

    LblTxt:
        id: lt4
        lblTxtIn: 'Support exposer time(ms)'

    LblTxt:
        id: lt5
        lblTxtIn: 'Job exposer time(ms)'

    Label:
        text:"Number of Layers"
    Button:
        text: 'OK'
        size_hint: 0.5,None
        height: 30
        on_release: root.print_something()

Output