Android Xamarin列表视图分组
我正在处理xamarin.froms中的列表视图。我可以为每个记录轻松地在listview中填充listitem:Android Xamarin列表视图分组,android,listview,xamarin,cross-platform,xamarin.forms,Android,Listview,Xamarin,Cross Platform,Xamarin.forms,我正在处理xamarin.froms中的列表视图。我可以为每个记录轻松地在listview中填充listitem: [ {"cat":1, "name":"alpha"}, {"cat":1, "name":"beta"}, {"cat":1, "name":"gamma"}, {"cat":2, "name":"john"}, {"cat":2, "name":"william"}, {"cat":2, "name":"smith"},
[
{"cat":1, "name":"alpha"},
{"cat":1, "name":"beta"},
{"cat":1, "name":"gamma"},
{"cat":2, "name":"john"},
{"cat":2, "name":"william"},
{"cat":2, "name":"smith"},
{"cat":2, "name":"steve"},
{"cat":3, "name":"abc"},
{"cat":3, "name":"xyz"}
]
//listview中的9项来自此json源
但我想要的是将所有项目分组到某个键值上,在这里说“cat”
,并实现如下功能:
任何对此的建议或方法都将不胜感激。Xamarin.Forms ListView支持分组。请查看他们的文档以了解如何使用它。将数据分组到集合中,并将这些集合添加到ListView中。集合必须是您自己的类,并具有用于将组与绑定的属性 这里有一个演练: 在ListView上设置分组,包括将每个组绑定到的属性,在本例中为“GroupKey” 然后分组添加数据(例如列表列表)。这通常意味着您需要创建自己的类来显示分组,例如:
public class Grouping<K, T> : ObservableCollection<T>
{
// NB: This is the GroupDisplayBinding above for displaying the header
public K GroupKey { get; private set; }
public Grouping(K key, IEnumerable<T> items)ac
{
GroupKey = key;
foreach (var item in items)
this.Items.Add(item);
}
}
查看它,了解有关为什么在分组
类中使用模板K
而不是字符串的解释,以及如何自定义标题外观等:(归功于@pnavk答案中的链接)在我的环境中,代码在此url中不起作用 不起作用的代码在这里
var partnersSorted = from item in Partners
orderby item.UserName
group item by item.UserNameSort into PartnersGroup
select new Grouping<string, Monkey>(PartnersGroup.Key, PartnersGroup);
MonkeysGrouped = new ObservableCollection<Grouping<string, Monkey>>(partnersSorted);
PartnersGroup.cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
namespace NewHeats.Models
{
public class PartnersGrouping<K,T> : ObservableCollection<T>
{
public K Key { get; private set; }
public PartnersGrouping(K key,IEnumerable<T> items)
{
Key = key;
foreach (var item in items)
{
this.Items.Add(item);
}
}
}
}
使用系统;
使用System.Collections.Generic;
使用System.Collections.ObjectModel;
名称空间NewHeats.Models
{
公共类合作伙伴组:ObservableCollection
{
公钥{get;private set;}
公共合作伙伴分组(K键,IEnumerable项)
{
钥匙=钥匙;
foreach(项目中的var项目)
{
此.Items.Add(item);
}
}
}
}
PartnersViewModel.cs
using System;
using System.Windows.Input;
using System.ComponentModel;
using System.Collections.ObjectModel;
using Xamarin.Forms;
using NewHeats.Models;
using System.Threading.Tasks;
using System.Diagnostics;
using System.Linq;
using System.Diagnostics.Contracts;
namespace NewHeats.ViewModels
{
public class PartnersViewModel : BaseViewModel
{
public Item Me
{
get;
set;
}
public ObservableCollection<Item> Partners { get; set; }
public ObservableCollection<PartnersGrouping<string, Item>> PartnersGrouped { get; set; }
public Item SelectedPartner { get; set; }
public Command LoadPartnersCommand { get; set; }
public PartnersViewModel()
{
Title = "Partners";
Partners = new ObservableCollection<Item>();
PartnersGrouped = new ObservableCollection<PartnersGrouping<string, Item>>();
LoadPartnersCommand = new Command(async() =>await ExecuteLoadPartnersCommand());
}
async Task ExecuteLoadPartnersCommand()
{
Contract.Ensures(Contract.Result<Task>() != null);
if (IsBusy)
return;
IsBusy = true;
try
{
Me = await MockUsrDataStore.GetItemAsync("naoto");
Partners.Clear();
var allfriends = await MockFriDataStore.GetItemsAsync(true);
var myFriends = allfriends.Where(x => x.MyId == Me.Id);
var allUsers = await MockUsrDataStore.GetItemsAsync(true);
foreach (var item in myFriends)
{
var partner = allUsers.FirstOrDefault(x => x.Id == item.FriendId);
if (partner!=null)
{
Partners.Add(partner);
}
}
var sortedpartners = Partners.OrderBy(x => x.UserName).GroupBy(y => y.UserNameSort);
foreach (var item in sortedpartners)
{
PartnersGrouped.Add(new PartnersGrouping<string, Item>(item.Key, Partners.Where(x=>x.UserNameSort == item.Key)));
}
}
catch (Exception ex)
{
Debug.WriteLine(ex);
}
finally
{
IsBusy = false;
}
}
}
}
使用系统;
使用System.Windows.Input;
使用系统组件模型;
使用System.Collections.ObjectModel;
使用Xamarin.Forms;
使用NewHeats.Models;
使用System.Threading.Tasks;
使用系统诊断;
使用System.Linq;
使用System.Diagnostics.Contracts;
名称空间NewHeats.ViewModels
{
公共类PartnersViewModel:BaseViewModel
{
公共物品
{
得到;
设置
}
公共可观测集合伙伴{get;set;}
公共ObservableCollection合作伙伴分组{get;set;}
公共项SelectedPartner{get;set;}
公共命令LoadPartnersCommand{get;set;}
公共合作伙伴可视模型()
{
Title=“合伙人”;
Partners=新的ObservableCollection();
PartnersGroup=新的ObservableCollection();
LoadPartnersCommand=new命令(async()=>await ExecuteLoadPartnersCommand());
}
异步任务执行器ADPARTNERSCOMAND()
{
Contract.sure(Contract.Result()!=null);
如果(忙)
返回;
IsBusy=true;
尝试
{
Me=wait MockUsrDataStore.GetItemAsync(“naoto”);
Partners.Clear();
var allfriends=wait MockFriDataStore.GetItemsAsync(true);
var myFriends=allfriends.Where(x=>x.MyId==Me.Id);
var allUsers=await MockUsrDataStore.GetItemsAsync(true);
foreach(myFriends中的变量项)
{
var partner=allUsers.FirstOrDefault(x=>x.Id==item.FriendId);
if(partner!=null)
{
合作伙伴。添加(合作伙伴);
}
}
var sortedpartners=Partners.OrderBy(x=>x.UserName).GroupBy(y=>y.UserNameSort);
foreach(分类合作伙伴中的var项目)
{
添加(新的PartnersGroup(item.Key,Partners.Where(x=>x.UserNameSort==item.Key));
}
}
捕获(例外情况除外)
{
Debug.WriteLine(ex);
}
最后
{
IsBusy=false;
}
}
}
}
PartnerPage.xaml
<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="NewHeats.Views.PartnersPage" xmlns:vm="clr-namespace:NewHeats.ViewModels" xmlns:controls="clr-namespace:ImageCircle.Forms.Plugin.Abstractions;assembly=ImageCircle.Forms.Plugin" Title="{Binding Title}">
<ContentPage.Resources>
<ResourceDictionary>
<!--Page Level Resources: Compatibile with Xamarin Live Player -->
<Color x:Key="Primary">#2196F3</Color>
<Color x:Key="Accent">#96d1ff</Color>
<Color x:Key="LightTextColor">#999999</Color>
</ResourceDictionary>
</ContentPage.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<ScrollView Grid.Row="0">
<StackLayout Orientation="Vertical" Padding="16,40,16,40" Spacing="10">
<ListView ItemsSource="{Binding PartnersGrouped}"
HasUnevenRows="true"
VerticalOptions="FillAndExpand"
IsPullToRefreshEnabled="true"
CachingStrategy="RecycleElement"
IsRefreshing="{Binding IsBusy, Mode=OneWay}"
RefreshCommand="{Binding LoadPartnersCommand}"
ItemSelected="Handle_ItemSelected"
SelectedItem="{Binding SelectedPartner}"
GroupDisplayBinding="{Binding Key}"
IsGroupingEnabled="true"
GroupShortNameBinding="{Binding Key}">
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell Height="25">
<StackLayout VerticalOptions="FillAndExpand"
Padding="5"
BackgroundColor="#3498DB">
<Label Text="{Binding Key}" TextColor="White" VerticalOptions="Center"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="60"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="60"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<controls:CircleImage Source="husky.jpg"
Aspect="AspectFill"
Grid.Column="0"
Grid.Row="0"
WidthRequest="60"
HeightRequest="60">
</controls:CircleImage>
<StackLayout Orientation="Vertical" Grid.Column="1">
<Label Text="{Binding UserName}" VerticalTextAlignment="Center"/>
</StackLayout>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ScrollView>
</Grid>
</ContentPage>
#2196F3
#96d1ff
#999999
谢谢
var sortedPartners = Partners.OrderBy(x => x.UserName).GroupBy(y => y.UserNameSort);
foreach (var item in sortedPartners)
{
PartnersGrouped.Add(new PartnersGrouping<string, Item>(item.Key, Partners.Where(x=>x.UserNameSort == item.Key)));
}
using System;
namespace NewHeats.Models
{
public class Item
{
public string Id
{
get;
set;
}
public string UserName
{
get;
set;
}
public DateTime RegisterDate
{
get;
set;
}
public string Field
{
get;
set;
}
public string Password
{
get;
set;
}
public int Heats
{
get;
set;
}
public string UserNameSort
{
get
{
if (string.IsNullOrWhiteSpace(UserName) || UserName.Length == 0)
return "?";
return UserName[0].ToString().ToUpper();
}
}
}
}
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
namespace NewHeats.Models
{
public class PartnersGrouping<K,T> : ObservableCollection<T>
{
public K Key { get; private set; }
public PartnersGrouping(K key,IEnumerable<T> items)
{
Key = key;
foreach (var item in items)
{
this.Items.Add(item);
}
}
}
}
using System;
using System.Windows.Input;
using System.ComponentModel;
using System.Collections.ObjectModel;
using Xamarin.Forms;
using NewHeats.Models;
using System.Threading.Tasks;
using System.Diagnostics;
using System.Linq;
using System.Diagnostics.Contracts;
namespace NewHeats.ViewModels
{
public class PartnersViewModel : BaseViewModel
{
public Item Me
{
get;
set;
}
public ObservableCollection<Item> Partners { get; set; }
public ObservableCollection<PartnersGrouping<string, Item>> PartnersGrouped { get; set; }
public Item SelectedPartner { get; set; }
public Command LoadPartnersCommand { get; set; }
public PartnersViewModel()
{
Title = "Partners";
Partners = new ObservableCollection<Item>();
PartnersGrouped = new ObservableCollection<PartnersGrouping<string, Item>>();
LoadPartnersCommand = new Command(async() =>await ExecuteLoadPartnersCommand());
}
async Task ExecuteLoadPartnersCommand()
{
Contract.Ensures(Contract.Result<Task>() != null);
if (IsBusy)
return;
IsBusy = true;
try
{
Me = await MockUsrDataStore.GetItemAsync("naoto");
Partners.Clear();
var allfriends = await MockFriDataStore.GetItemsAsync(true);
var myFriends = allfriends.Where(x => x.MyId == Me.Id);
var allUsers = await MockUsrDataStore.GetItemsAsync(true);
foreach (var item in myFriends)
{
var partner = allUsers.FirstOrDefault(x => x.Id == item.FriendId);
if (partner!=null)
{
Partners.Add(partner);
}
}
var sortedpartners = Partners.OrderBy(x => x.UserName).GroupBy(y => y.UserNameSort);
foreach (var item in sortedpartners)
{
PartnersGrouped.Add(new PartnersGrouping<string, Item>(item.Key, Partners.Where(x=>x.UserNameSort == item.Key)));
}
}
catch (Exception ex)
{
Debug.WriteLine(ex);
}
finally
{
IsBusy = false;
}
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="NewHeats.Views.PartnersPage" xmlns:vm="clr-namespace:NewHeats.ViewModels" xmlns:controls="clr-namespace:ImageCircle.Forms.Plugin.Abstractions;assembly=ImageCircle.Forms.Plugin" Title="{Binding Title}">
<ContentPage.Resources>
<ResourceDictionary>
<!--Page Level Resources: Compatibile with Xamarin Live Player -->
<Color x:Key="Primary">#2196F3</Color>
<Color x:Key="Accent">#96d1ff</Color>
<Color x:Key="LightTextColor">#999999</Color>
</ResourceDictionary>
</ContentPage.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<ScrollView Grid.Row="0">
<StackLayout Orientation="Vertical" Padding="16,40,16,40" Spacing="10">
<ListView ItemsSource="{Binding PartnersGrouped}"
HasUnevenRows="true"
VerticalOptions="FillAndExpand"
IsPullToRefreshEnabled="true"
CachingStrategy="RecycleElement"
IsRefreshing="{Binding IsBusy, Mode=OneWay}"
RefreshCommand="{Binding LoadPartnersCommand}"
ItemSelected="Handle_ItemSelected"
SelectedItem="{Binding SelectedPartner}"
GroupDisplayBinding="{Binding Key}"
IsGroupingEnabled="true"
GroupShortNameBinding="{Binding Key}">
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell Height="25">
<StackLayout VerticalOptions="FillAndExpand"
Padding="5"
BackgroundColor="#3498DB">
<Label Text="{Binding Key}" TextColor="White" VerticalOptions="Center"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="60"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="60"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<controls:CircleImage Source="husky.jpg"
Aspect="AspectFill"
Grid.Column="0"
Grid.Row="0"
WidthRequest="60"
HeightRequest="60">
</controls:CircleImage>
<StackLayout Orientation="Vertical" Grid.Column="1">
<Label Text="{Binding UserName}" VerticalTextAlignment="Center"/>
</StackLayout>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ScrollView>
</Grid>
</ContentPage>