Is ListView used the same way as RecycleView? - python-3.x

Question

I'm trying to have self.search_results.data printed on my console, but this is not working. Am I using RecycleView the right way? The textbook I'm studying with is from 2014 and uses ListView. I found on the internet that ListView is deprecated. I can't seem to understand how the RecycleView actually works. I've read the documentation, but still can't see.
Kivy:
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()
The strings in the list should be printed on the console

Answer 1

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, one needs to 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"
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