关于sl控件数据绑定的一个问题，是怎么绑定的？

Question

最近在读一些sl的源代码，看到这样的代码

 <CheckBox Content="AutoCommit" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=AutoCommit}" Margin="4" />
 <CheckBox Content="AutoEdit" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=AutoEdit}" Margin="4" />
 <CheckBox Content="CanUserAddItems" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=CanUserAddItems}" Margin="4" />
 <CheckBox Content="CanUserDeleteItems" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=CanUserDeleteItems}" Margin="4" />
 <CheckBox Content="CommandButtonsVisibility" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=AutoEdit}" Margin="4" />

第一个问题：里边有个IsChecked属性是否默认选中，它是绑定的一个实体类的哪个字段呀
例如第一行代码，是绑定的path后的那个AutoCommit字段吗？

请看后台代码：

public partial class DataFormSample : UserControl
    {
        public DataFormSample()
        {
            InitializeComponent();
            DataContext = Contact.People;
        }
    }

我找到了这个Contact.People实体类，并没发现有“AutoCommit字段”呀。全部

第二个问题：{Binding ElementName=dataForm, Mode=TwoWay, Path=AutoCommit}
麻烦解释下大括号里的每个代码的作用，Mode=TwoWay是双向绑定，我明白这个。其他两个就不知道了。

第三个问题：这样的绑定方式，为什么以前在asp.net，html的编程里没涉及到呢？
我觉得直接后台c#里给控件赋值不就可以了吗，为什么还需要这样的绑定呢，不过绑定的方式确实很简便。

谢谢

---

生活因软件而改变

Answer 1

1.绑定到People类型AutoCommit属性，请再查看People类

2.
OneTime 一次绑定，程序生成时进行一次绑定 
OneWay 单项绑定，程序生成时进行绑定，当绑定源类型的值更改，其绑定值也随其更改
TowWay 双向绑定，程序生成时进行绑定，当绑定源类型的值更改，其绑控件值也随其更改 或 当绑定的控件进行操作，其绑定的值进行更改，其绑定类型源值也随之更改。

3.直接赋值可以做一次绑定或单项绑定，双项绑定就不好做了。

Answer 2

Silverlight 2.0 数据绑定：
    Binding - 将绑定目标对象的属性与数据源联接起来
        Source - 绑定的数据源
        Mode - 绑定的数据流的方向 [System.Windows.Data.BindingMode枚举]
            BindingMode.OneTime - 一次绑定。创建绑定时一次性地更新绑定目标对象的属性
            BindingMode.OneWay - 单向绑定（默认值）。数据源的改变会自动通知到绑定目标对象的属性
            BindingMode.TwoWay - 双向绑定。数据源或绑定目标对象的属性的值发生改变时会互相通知。显然，做数据验证的话一定要是双向绑定

这里例子很详细：http://www.cnblogs.com/webabcd/archive/2009/01/05/1337190.html

---

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Answer 3

谢谢楼上两位，可是问题我还是没搞清楚呀。

一，“1.绑定到People类型AutoCommit属性，请再查看People类”，我看过people类了(people只是个Contact类的静态属性，请看下帖代码)，确实没有“AutoCommit”属性呀。
       我一会贴过来这个类的代码，麻烦你们看看。

二，：{Binding ElementName=dataForm, Path=AutoCommit}
      请问ElementName是什么意思？要绑定的类的类名？
      请问Path是什么意思？要绑定的属性名，估计这个我猜对了？

谢谢呀。

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Answer 4

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace System.Windows.Controls.Samples
{
    public class Contact : INotifyPropertyChanged, IEditableObject
    {
        public Contact();

        [Display(Name = "City", Description = "City of residence", GroupName = "Address")]
        [Required]
        public string City { get; set; }
        [Display(Name = "Email", Description = "An e-mail address of the form <name>@<domain>, such as [e-mail]")]
        [RegularExpression(@"^([a-zA-Z0-9\!\%\$\%\*\/\?\|\^\{\}\`\~\&\'\+\-\=_]\.?)*[a-zA-Z0-9\!\%\$\%\*\/\?\|\^\{\}\`\~\&\'\+\-\=_]@((([a-zA-Z0-9\!\%\$\%\*\/\?\|\^\{\}\`\~\&\'\+\-\=_]\.?)*[a-zA-Z0-9\!\%\$\%\*\/\?\|\^\{\}\`\~\&\'\+\-\=_])|(\[\d+\.\d+\.\d+\.\d+\]))$", ErrorMessage = "Not a valid e-mail address.")]
        public string Email { get; set; }
        [Required]
        [Display(Name = "First Name", GroupName = "Name")]
        public string FirstName { get; set; }
        [Display(Name = "Business Address", Description = "Indicates that the address is a business address.")]
        public bool IsBusinessAddress { get; set; }
        public static Contact JohnDoe { get; }
        [Required]
        [Display(Name = "Last Name", GroupName = "Name")]
        public string LastName { get; set; }
        public static IEnumerable<Contact> People { get; }
        [Display(Name = "Phone", Description = "Phone number of the form (###) ###-####")]
        [RegularExpression(@"^\(\d\d\d\) \d\d\d\-\d\d\d\d$", ErrorMessage = "Not a valid phone number.  Please enter a phone number that matches the format (###) ###-####")]
        public string Phone { get; set; }
        [Required]
        [Display(Name = "State", Description = "State abbreviation", GroupName = "Address")]
        [RegularExpression("^[a-zA-Z][a-zA-Z]$", ErrorMessage = "Not a valid state abbreviation (e.g. CA or TN)")]
        public string State { get; set; }
        [Display(Name = "Street Address", GroupName = "Address")]
        [Required]
        public string Street1 { get; set; }
        [Display(Name = "Secondary Street Address", Description = "Additional street address information, such as apartment number or P.O. Box", GroupName = "Address")]
        public string Street2 { get; set; }
        [Display(Name = "Zip", Description = "Five-digit zip code", GroupName = "Address")]
        [RegularExpression(@"^\d\d\d\d\d$", ErrorMessage = "Zip codes must be 5-digit numbers.")]
        [Required]
        public int Zip { get; set; }

        public event PropertyChangedEventHandler PropertyChanged;

        public void BeginEdit();
        public void CancelEdit();
        public void EndEdit();
        protected virtual void OnPropertyChanged(string propName);
    }
}

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Answer 5

 public static IEnumerable<Contact> People { get; }

People贴出来看看

Answer 6

{Binding 属性名,Mode=绑定模式,ElementName=绑定元素, Path=绑定元素的属性}

Answer 7

/// <summary>
        /// Gets a stock group of contacts with valid contact information.
        /// </summary>
        public static IEnumerable<Contact> People
        {
            get
            {
                return new ObservableCollection<Contact>
                {
                    new Contact
                    {
                        FirstName = "Michiel",
                        LastName = "Wories",
                        Phone = "[phone]",
                        Street1 = "199 Anywhere Street",
                        City = "AnotherTown",
                        State = "NY",
                        Zip = 39495
                    },
                    new Contact
                    {
                        FirstName = "John",
                        LastName = "Yokim",
                        Phone = "[phone]",
                        Street1 = "3241 Someplace Street",
                        City = "Anytown",
                        State = "NY",
                        Zip = 93258
                    },
                    new Contact
                    {
                        FirstName = "Yanlai",
                        LastName = "Guo",
                        Phone = "[phone]",
                        Street1 = "2241 Somewhere Street",
                        City = "Anytown",
                        State = "WA",
                        Zip = 18444
                    }
                };
            }
        }

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Answer 8

熊哥，你看，咋就找不到AutoCommit属性呀。谢谢呀

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视别人的帮助为恩赐~

Answer 9

<CheckBox Content="AutoCommit" IsChecked="{Binding ElementName=dataForm, Mode=TwoWay, Path=AutoCommit}" Margin="4" />

重新解释一遍，上面这句的意思是，你的这个CheckBox控件就跟你dataForm控件的AutoCommit的值相关了。

相当于你的数据源对应到dataForm这个控件中

而上面这个ChechBox只关心你detaForm控件的AutoCommit，数据源没有并不代表dataForm控件没有这个属性，再看看

Answer 10

熊哥，你看，咋就找不到AutoCommit属性呀。谢谢呀

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<UserControl x:Class="SilverlightApplication2.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Width="400" Height="300">
    <Canvas x:Name="LayoutRoot" Background="White" Width="400" Height="300" >

        <Rectangle x:Name="Kare" Width="100" Height="100" Fill="Red" Canvas.Top="50" Canvas.Left="140">
            <Rectangle.Projection>
                <PlaneProjection x:Name="Kare3d" CenterOfRotationX="0.5" CenterOfRotationY="0.5" CenterOfRotationZ="0"/>
            </Rectangle.Projection>
        </Rectangle>

        <Slider Minimum="0" Maximum="360" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=RotationX}" Canvas.Left="20" Canvas.Top="200"/>

        <Slider Minimum="0" Maximum="360" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=RotationY}" Canvas.Left="20" Canvas.Top="230" />

        <Slider Minimum="0" Maximum="360" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=RotationZ}" Canvas.Left="20" Canvas.Top="260"/>

        <Slider Minimum="0" Maximum="1" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=CenterOfRotationX}" Canvas.Top="200" Canvas.Left="210"/>

        <Slider Minimum="0" Maximum="1" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=CenterOfRotationY}" Canvas.Top="230" Canvas.Left="210"/>

        <Slider Minimum="0" Maximum="1" Width="180" Value="{Binding ElementName=Kare3d, Mode=TwoWay, Path=CenterOfRotationZ}" Canvas.Top="260" Canvas.Left="210"/>

        <TextBlock Canvas.Top="180" Canvas.Left="20" Width="87" Height="16" FontWeight="Bold" Text="Rotation"/>
        <TextBlock Canvas.Top="180" Canvas.Left="210" Height="16" Width="118" Text="CenterOfRotation" FontWeight="Bold"/>
        <TextBlock Canvas.Top="200" Canvas.Left="4" Height="16" Width="8" Text="X" FontWeight="Bold"/>
        <TextBlock Canvas.Top="230" Canvas.Left="4" Height="16" Width="8" Text="Y" FontWeight="Bold"/>
        <TextBlock Canvas.Top="260" Canvas.Left="4" Height="16" Width="8" Text="Z" FontWeight="Bold"/>
    </Canvas>

</UserControl>

看上面这个例子可能更好理解，几个Silder的值都绑定在Kare3d这个控件上，RotationX这个值Kare3d并没有显示声明出来，但是PlaneProjection是可以取得这个值的，标识x坐标轴旋转的角度