我正在研究使用扩展方法进行强类型的Windows Forms数据绑定。在得到Xavier的帮助后,我已经完成了以下步骤:
using System;
using System.Linq.Expressions;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public static Binding Add<T>
(this ControlBindingsCollection dataBindings,
object dataSource,
Expression<Func<Control, object>> controlExpression,
Expression<Func<T, object>> objectExpression)
{
return Add(dataBindings, dataSource, controlExpression, objectExpression, false);
}
public static Binding Add<T>
(this ControlBindingsCollection dataBindings,
object dataSource,
Expression<Func<Control, object>> controlExpression,
Expression<Func<T, object>> objectExpression,
bool formattingEnabled)
{
string controlPropertyName = ProcessExpression(controlExpression.Body);
string bindingTargetName = ProcessExpression(objectExpression.Body);
return dataBindings
.Add(controlPropertyName, dataSource, bindingTargetName, formattingEnabled);
}
public static Binding Add<T, K>
(this ControlBindingsCollection dataBindings,
object dataSource,
Expression<Func<K, object>> controlExpression,
Expression<Func<T, object>> objectExpression)
{
return Add(dataBindings, dataSource, controlExpression, objectExpression, false);
}
public static Binding Add<T, K>
(this ControlBindingsCollection dataBindings,
object dataSource,
Expression<Func<K, object>> controlExpression,
Expression<Func<T, object>> objectExpression,
bool formattingEnabled
)
{
string controlPropertyName = ProcessExpression(controlExpression.Body);
string bindingTargetName = ProcessExpression(objectExpression.Body);
return dataBindings.Add(controlPropertyName, dataSource, bindingTargetName, formattingEnabled);
}
private static string ProcessExpression(Expression expression)
{
string propertyName;
if (expression is MemberExpression)
{
propertyName = ((MemberExpression) (expression)).Member.Name;
}
else if (expression is UnaryExpression)
{
propertyName = ((MemberExpression) ((UnaryExpression) (expression)).Operand).Member.Name;
}
else
{
throw new InvalidOperationException(
"Unknown expression type error in DataBindingsExtensionMethods.Add<T, K>");
}
return propertyName;
}
}
现在我可以像这样设置数据绑定:
txtBoundInt.DataBindings.Add<Contact>
(bindingSource, tb => tb.Text, contact => contact.Id);
或者这个:
cboBoundSelectedItem.DataBindings.Add
<Contact, ComboBox>
(bindingSource, cbo => cbo.SelectedItem, con => con.ContactType)
看起来有很多表达式的转换正在进行中。是否有更好的方法?
编辑:我找到了一个更好的方法,但因为将这个问题改成了那个答案而陷入麻烦 - 它由@Carl_G 在下面复制。