ListView 的使用方式和 RecycleView 一样吗？

Question

我正在尝试在我的控制台上打印 self.search_results.data，但这不起作用。我是否以正确的方式使用 RecycleView？我正在学习的教科书是 2014 年的，使用 ListView。我在互联网上发现 ListView 已被弃用。我似乎无法理解 RecycleView 的实际工作原理。我已经阅读了文档，但仍然看不到。

基维：

WeatherRoot:

<WeatherRoot>:
    AddLocationForm


<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
            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
        data: []

Python：

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty, ListProperty
from kivy.network.urlrequest import UrlRequest
from kivy.factory import Factory
import json


class WeatherApp(App):
    pass

class WeatherRoot(BoxLayout):
    pass


class AddLocationForm(BoxLayout):

    search_input = ObjectProperty()
    search_results = ObjectProperty()

    # do something
    def search_location(self):

        search_template = "http://api.openweathermap.org/data/2.5/find?q= 
        {}&type=like"
        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= cities
        print(self.search_results.data)

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

列表中的字符串应该打印在控制台上

Answer 1

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。

基维RecycleView » MVC (Model-View-Controller)

视图是通过处理data 生成的，本质上是一个列表 dicts，并使用这些 dicts 生成 viewclass 根据需要。它的设计基于MVC （模型-视图-控制器）模式。

• 模型：模型由您通过字典列表传入的data 形成。
• 视图：视图分为布局和视图，并使用适配器实现。
• Controller：控制器决定逻辑交互，由RecycleViewBehavior实现。

解决方案

要创建可选项目的 RecycleView，需要实现以下类作为viewclass 的一部分。该项目通常是一个小部件，例如Label、Button 或布局中的一组/行小部件（BoxLayout 或 GridLayout）。

视图类

• Selectabel 回收布局类，例如SelectableRecycleBoxLayout()，或SelectableRecycleGridLayout()
• 可选择的小部件类，例如SelectableLabel()、SelectableButton() 或 SelectableRow()

数据

• 为data 创建一个字典列表

示例

以下示例通过使用 RecycleView 说明了 ListView 的等效性。 viewclass 是可选的 RecycleBoxLayout 或 Label 小部件。该应用程序正在使用OpenWeatherMap 的API 检索英国伦敦（英国）的示例天气数据。

注意：

要使用真正的 API 点调用 OpenWeatherMap，您需要一个 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"
        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

输出