Question

我在我的viewmodel中为我的Xamarin Forms项目写了一些命令。我需要在我的按钮上访问这些命令，以便他们执行任务但是我不知道该怎么做。

我的ViewModel

TheDemo /视图模型/ MenupageViewModel.cs

using System;
using System.Windows.Input;
using Xamarin.Forms;

namespace TheDemo
{
    public class MenuPageViewModel
    {
        public ICommand GoDashboardCommand { get; set; }
        public ICommand GoRequirementsCommand { get; set; }
        public ICommand GoFixturesCommand { get; set; }
        public ICommand GoVesselsCommand { get; set; }
        public ICommand GoDutyBrokerCommand { get; set; }
        public ICommand GoSettingsCommand { get; set; }
        public ICommand GoInfoCommand { get; set; }

        public MenuPageViewModel()
        {
            GoDashboardCommand = new Command(GoDashboard);
            GoRequirementsCommand = new Command(GoRequirements);
            GoFixturesCommand = new Command(GoFixtures);
            GoVesselsCommand = new Command(GoVessels);
            GoDutyBrokerCommand = new Command(GoBroker);
            GoSettingsCommand = new Command(GoSettings);
            GoInfoCommand = new Command(GoInfo);
        }

        void GoDashboard(object obj) {
            App.NavigationPage.Navigation.PopToRootAsync();
            App.MenuIsPresented = false;
        }
        void GoRequirements(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Requirements());
            App.MenuIsPresented = false;
        }
        void GoFixtures(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Fixtures());
            App.MenuIsPresented = false;
        }
        void GoVessels(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Vessels());
            App.MenuIsPresented = false;
        }
        void GoBroker(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Duty());
            App.MenuIsPresented = false;
        }
        void GoSettings(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Settings());
            App.MenuIsPresented = false;
        }
        void GoInfo(object obj) {
            App.NavigationPage.Navigation.PushAsync(new Information());
            App.MenuIsPresented = false;
        }
    }
}

菜单 TheDemo / Menupage.cs

using System;
using System.Collections.Generic;
using OxyPlot;
using OxyPlot.Axes;

using OxyPlot.Series;
using OxyPlot.Xamarin.Forms;
using System.Windows.Input;
using Xamarin.Forms;
namespace TheDemo
{
    public partial class MenuPage : ContentPage
    {
        public MenuPage()
        {
            InitializeComponent();
            BindingContext = new MenuPageViewModel();

            Grid grid = new Grid();

            grid.Children.Add(
                        new Button {
                            Text = "Requirements",
                            BackgroundColor = Color.Orange,
                            TextColor = Color.White,
                            Command = //How do I access my commands in my viewmmodel?
                        }, 0, 1);

        }
    }
}

Answer 1

您应该在变量中设置Button，然后通过SetBinding绑定它。

示例代码：

var ButtonHolder = new Button {
                        Text = "Requirements",
                        BackgroundColor = Color.Orange,
                        TextColor = Color.White
                    };

ButtonHolder.SetBinding (Button.CommandProperty, "GoDashboardCommand");


grid.Children.Add(ButtonHolder, 0, 1);

Answer 2

首先，将视图模型映射到视图。为此，请将以下行添加到XAML中的视图的ContentPage标记中，如下所示。

要添加的行

xmlns:viewModels="clr-namespace:TheDemo.ViewModels; assembly=TheDemo"

实施例

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:viewModels="clr-namespace:TheDemo.ViewModels; assembly=TheDemo">

然后在内容页面标记

中添加此代码段

<ContentPage.BindingContext>
        <viewModels:MenuPageViewModel/>
    </ContentPage.BindingContext>

然后添加按钮并使用命令属性，如此

<Button Command="{Binding GoInfoCommand}"/>

根据您的应用程序更新程序集和命名空间。希望这能解决你的问题。

如何在Xamarin Forms按钮上访问我的viewmodel命令？

2 个答案: