Kivy:未知类<ListView>错误代码 [英] Kivy: Unknown class <ListView> error code

问题描述

这是main.py

from kivy.app import App类天气应用程序(应用程序):经过如果 __name__ == '__main__':WeatherApp().run()

weather.kv 是:

AddLocationForm:<AddLocationForm@BoxLayout>:方向:垂直"盒子布局:文本输入:按钮:文本:搜索"按钮:文本:当前位置"列表显示:item_strings:[帕洛阿尔托，MX"，帕洛阿尔托，美国"]

它似乎无法识别列表视图.我见过其他使用 listview 的from kivy.uix.listview import ListView".但这也不起作用，我不知道为什么.

kivy.factory.FactoryException: 未知类

解决方案

Kivy ListView » 已弃用

在最近发布的稳定 Kivy 版本 1.11.0 中不再定义 ListView.

Kivy

This is the main.py

from kivy.app import App
    
    
class WeatherApp(App):
    pass
    
    
if __name__ == '__main__':
    WeatherApp().run()

weather.kv is:

AddLocationForm:
    
<AddLocationForm@BoxLayout>:
    orientation: 'vertical'
    BoxLayout:
        TextInput:
        Button:
            text: "Search"
        Button:
            text: "Current Location"
    ListView:
        item_strings: ["Palo Alto, MX", "Palo Alto, US"]

It doesn't seem to recognize listview. I have seen other use listview with "from kivy.uix.listview import ListView" but that doesn't work either, i do not know why.

kivy.factory.FactoryException: Unknown class

解决方案

Kivy ListView » Deprecated

ListView is no longer defined in the recently released stable Kivy version 1.11.0.

Kivy RecycleView » MVC (Model-View-Controller)

The view is generatad by processing the data, essentially a list of dicts, and uses these dicts to generate instances of the viewclass as required. Its design is based on the MVC (Model-view-controller) pattern.

• Model: The model is formed by data you pass in via a list of dicts.
• View: The View is split across layout and views and implemented using adapters.
• Controller: The controller determines the logical interaction and is implemented by RecycleViewBehavior.

Solution

To create a RecycleView of selectable item, implement the following classes as part of the viewclass. The item is usually a widget e.g. Label, Button, or a group/row of widgets in a layout (BoxLayout or GridLayout).

viewclass

• Selectabel recycle layout class, e.g. SelectableRecycleBoxLayout(), or SelectableRecycleGridLayout()
• Selectable widget class, e.g. SelectableLabel(), SelectableButton(), or SelectableRow()

data

• Creates a list of dicts for data

Example

The following example illustrates the equivalence of a ListView by using RecycleView. The viewclass is a selectable RecycleBoxLayout of Label widget. The app is using OpenWeatherMap's API to retrieve a sample weather data of London, GB (Great Britain).

Note:

To make calls to OpenWeatherMap using the real API point, you need an API key (APPID).

main.py

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.recycleview.views import RecycleDataViewBehavior
from kivy.uix.label import Label
from kivy.properties import BooleanProperty, ObjectProperty
from kivy.uix.recycleboxlayout import RecycleBoxLayout
from kivy.uix.behaviors import FocusBehavior
from kivy.uix.recycleview.layout import LayoutSelectionBehavior
from kivy.network.urlrequest import UrlRequest
from kivy.lang import Builder

import json


class SelectableRecycleBoxLayout(FocusBehavior, LayoutSelectionBehavior,
                                 RecycleBoxLayout):
    ''' Adds selection and focus behaviour to the view. '''


class SelectableLabel(RecycleDataViewBehavior, Label):
    ''' Add selection support to the Label '''
    index = None
    selected = BooleanProperty(False)
    selectable = BooleanProperty(True)

    def refresh_view_attrs(self, rv, index, data):
        ''' Catch and handle the view changes '''
        self.index = index
        return super(SelectableLabel, self).refresh_view_attrs(
            rv, index, data)

    def on_touch_down(self, touch):
        ''' Add selection on touch down '''
        if super(SelectableLabel, self).on_touch_down(touch):
            return True
        if self.collide_point(*touch.pos) and self.selectable:
            return self.parent.select_with_touch(self.index, touch)

    def apply_selection(self, rv, index, is_selected):
        ''' Respond to the selection of items in the view. '''
        self.selected = is_selected


class AddLocationForm(BoxLayout):
    search_input = ObjectProperty()
    search_results = ObjectProperty()

    def search_location(self):
        search_template = "https://samples.openweathermap.org/data/2.5/find?q={}&appid=b6907d289e10d714a6e88b30761fae22"
        # search_template = "https://api.openweathermap.org/data/2.5/find?q={}&typle=like&appid=xyz"    # Replace 'xyz' with your API Key (APPID)
        search_url = search_template.format(self.search_input.text)
        request = UrlRequest(search_url, self.found_location)

    def found_location(self, request, data):
        data = json.loads(data.decode()) if not isinstance(data, dict) else data
        cities = ["{} ({})".format(d['name'], d['sys']['country']) for d in data['list']]
        self.search_results.data = [{'text': str(x)} for x in cities]
        print(f"self.search_results.data={self.search_results.data}")


class WeatherRoot(BoxLayout):
    pass


class TestApp(App):
    title = "Weather App"

    def build(self):
        return Builder.load_file("main.kv")


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

main.kv

WeatherRoot:

<WeatherRoot>:
    AddLocationForm:

<SelectableLabel>:
    # Draw a background to indicate selection
    canvas.before:
        Color:
            rgba: (1, 0, 0, 1) if self.selected else (.0, 0.9, .1, .3)
        Rectangle:
            pos: self.pos
            size: self.size
        Color:
            rgba: (0, 0.9, .1, .3)
        Rectangle:
            pos: self.pos
            size: self.size

<AddLocationForm>:
    orientation: "vertical"

    search_input: search_input
    search_results: search_results_list

    BoxLayout:
        height: "40dp"
        size_hint_y:None

        TextInput:
            id: search_input
            size_hint_x: 50
            focus: True
            multiline: False
            hint_text: 'Your city name'
            on_text_validate: root.search_location()


        Button:
            text: "Search"
            size_hint_x: 25
            on_press: root.search_location()

        Button:
            text: "Current Location"
            size_hint_x: 25

    RecycleView:
        id: search_results_list

        viewclass: 'SelectableLabel'

        SelectableRecycleBoxLayout:
            default_size: None, dp(26)
            default_size_hint: 1, None
            size_hint_y: None
            height: self.minimum_height
            orientation: 'vertical'
            multiselect: True
            touch_multiselect: True

Output

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