问题描述
我有一个完美运行的 CRUD 功能，我需要做的是使用 CRUD 功能启用添加菜单项。
使用 CRUD 创建的新项目应显示在此处：Image example
我试图在以下问题中找到解决方案：Xamarin Forms Dynamically add shell items 和许多其他问题。但这些文章没有回答我的问题。>
如前所述，我理解你的逻辑，但我无法将它实现到我的项目中。我在这方面很新，所以我会分享一些代码，希望有人能提供帮助。
这是我的 AppShell.xaml
<?xml version="1.0" encoding="UTF-8"?>
<Shell xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MyTestApplication.Views"
xmlns:viewmodels="clr-namespace:MyTestApplication.viewmodels;assembly=MyTestApplication"
Title="MyTestApplication"
x:Class="MyTestApplication.AppShell">
<Shell.Resources>
<ResourceDictionary>
<Style x:Key="BaseStyle" targettype="Element">
<Setter Property="Shell.BackgroundColor" Value="{StaticResource Primary}" />
<Setter Property="Shell.ForegroundColor" Value="White" />
<Setter Property="Shell.TitleColor" Value="White" />
<Setter Property="Shell.disabledColor" Value="#B4FFFFFF" />
<Setter Property="Shell.UnselectedColor" Value="#95FFFFFF" />
<Setter Property="Shell.TabBarBackgroundColor" Value="{StaticResource Primary}" />
<Setter Property="Shell.TabBarForegroundColor" Value="White"/>
<Setter Property="Shell.TabBarUnselectedColor" Value="#95FFFFFF"/>
<Setter Property="Shell.TabBarTitleColor" Value="White"/>
</Style>
<Style targettype="TabBar" BasedOn="{StaticResource BaseStyle}" />
<Style targettype="FlyoutItem" BasedOn="{StaticResource BaseStyle}" />
<Style Class="MenuItemLayoutStyle" targettype="Layout" ApplyToDerivedTypes="True">
<Setter Property="visualstatemanager.VisualStateGroups">
<VisualStateGroupList>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="normal">
<VisualState.Setters>
<Setter TargetName="FlyoutItemLabel" Property="Label.TextColor" Value="{StaticResource Primary}" />
</VisualState.Setters>
</VisualState>
</VisualStateGroup>
</VisualStateGroupList>
</Setter>
</Style>
</ResourceDictionary>
</Shell.Resources>
<FlyoutItem Title="Home" Icon="home.png">
<ShellContent Route="MainPage" ContentTemplate="{DataTemplate local:MainPage}" />
</FlyoutItem>
<FlyoutItem Title="Settings" Icon="setting.png">
<ShellContent Route="SettingsPage" ContentTemplate="{DataTemplate local:SettingsPage}" />
</FlyoutItem>
<MenuItem Icon="logout.png" Text="logout" StyleClass="MenuItemLayoutStyle" Clicked="OnMenuItemClicked">
</MenuItem>
<TabBar >
<ShellContent Route="LoginPage" ContentTemplate="{DataTemplate local:LoginPage}" />
</TabBar>
</Shell>
这是我的 AppShell.xaml.cs
public partial class AppShell : Xamarin.Forms.Shell
{
public List<ElseMenuItem> FlyoutItems { get; set; } = new List<ElseMenuItem>();
public AppShell()
{
InitializeComponent();
}
private async void OnMenuItemClicked(object sender,EventArgs e)
{
await Shell.Current.GoToAsync("//LoginPage");
}
}
这是我的 AddUrl.xaml.cs（我想在菜单中添加的项目是“URL 按钮”，所以当我点击时，它会将我带到一个特定的网页。这就是我称之为它的原因添加网址)
[XamlCompilation(XamlCompilationoptions.Compile)]
public partial class AddUrl : ContentPage
{
private DbService _services;
bool _isUpdate;
int urlId;
public AddUrl()
{
InitializeComponent();
_services = new DbService(); // Initializing db service
_isUpdate = false; // Boolean logic,if constructor calls without any Url parameters it is going to add new record
}
public AddUrl(Urls obj)
{
//If constructor calls parameter of Url object,it is going to update the record
InitializeComponent();
_services = new DbService();
if (obj != null)
{
urlId = obj.Id;
TxtUrlName.Text = obj.Name;
TxtUrl.Text = obj.Url;
_isUpdate = true;
}
}
private async void btnSaveUpdate_Clicked(object sender,EventArgs e)
{
Urls obj = new Urls(); // Use of url object
//Text Box value
obj.Name = TxtUrlName.Text;
obj.Url = TxtUrl.Text;
// If _isUpdate is true,call UpdateUrls method
if (_isUpdate)
{
obj.Id = urlId;
await _services.UpdateUrls(obj);
}
// Else insert record
else
{
_services.InsertUrls(obj);
}
await this.Navigation.PopModalAsync();
}
}
这是 AddUrl.xaml
<ContentPage.Content>
<StackLayout Margin="10" VerticalOptions="StartAndExpand" HorizontalOptions="FillAndExpand">
<Entry x:Name="TxtUrlName" Placeholder="Enter Url Name" />
<Entry x:Name="TxtUrl" Placeholder="Enter Url" />
<Button x:Name="btnSaveUpdate" Text="Save" Clicked="btnSaveUpdate_Clicked" />
</StackLayout>
</ContentPage.Content>
最后我有一个 SettingsPage.cs，我可以在其中显示和添加 url。
[XamlCompilation(XamlCompilationoptions.Compile)]
public partial class SettingsPage : ContentPage
{
public Settings Settings { get; set; }
DbService services;
public SettingsPage ()
{
InitializeComponent();
// Creates the Settings Model
Settings = new Settings();
// Sets the Settings Model as the BindingContext for "filling" the SettingsPage with the current AppSettings.
BindingContext = Settings;
services = new DbService();
}
protected async override void OnAppearing()
{
showUrl(); // Returns GetAllUrls
base.OnAppearing();
}
private void showUrl()
{
var res = services.GetAllUrls();
lstUrls.ItemsSource = res; // Binding with listview
}
//This method is used to insert data into db
private async void BtnAddRecord_Clicked(object sender,EventArgs e)
{
await this.Navigation.PushModalAsync(new AddUrl(),true);
}
// display alert for update and delete
private async void lstData_ItemSelected(object sender,selecteditemchangedEventArgs e)
{
if (e.SelectedItem != null)
{
Urls obj = (Urls) e.SelectedItem;
string res = await displayActionSheet("Operation","Cancel",null,"Update","Delete");
switch (res)
{
case "Update":
await this.Navigation.PushModalAsync(new AddUrl(obj),true);
break;
case "Delete":
services.DeleteUrl(obj);
showUrl();
break;
}
lstUrls.SelectedItem = null;
}
}
}
再次：我不知道如何在我的代码中实现逻辑。我有一个完美运行的 CRUD 函数，但我需要使用它来动态添加菜单中的项目。希望有人能给我指路。
谢谢！
解决方法
关于你的CRUD操作，你可以在操作数据库之前调用Items.Add()方法和Items.Remove()方法。
比如在AddUrl.xaml.cs中添加菜单项：
private async void btnSaveUpdate_Clicked(object sender,EventArgs e)
{
Urls obj = new Urls(); // Use of url object
//Text box value
obj.Name = TxtUrlName.Text;
obj.Url = TxtUrl.Text;
// If _isUpdate is true,call UpdateUrls method
if (_isUpdate)
{
obj.Id = urlId;
await _services.UpdateUrls(obj);
}
// Else insert record
else
{
_services.InsertUrls(obj);
}
AppShell.Current.Items.Add(your menuitem);//add the menuitems
await this.Navigation.PopModalAsync();
}
删除 SettingsPage.cs 中的菜单项：
private async void lstData_ItemSelected(object sender,SelectedItemChangedEventArgs e)
{
if (e.SelectedItem != null)
{
Urls obj = (Urls) e.SelectedItem;
string res = await DisplayActionSheet("Operation","Cancel",null,"Update","Delete");
switch (res)
{
case "Update":
await this.Navigation.PushModalAsync(new AddUrl(obj),true);
break;
case "Delete":
services.DeleteUrl(obj);
AppShell.Current.Items.Remove(your menuitem); //remove
showUrl();
break;
}
lstUrls.SelectedItem = null;
}
}