[英]Getting sub property names strongly typed
使用控件和網格的數據綁定對象,我討厭屬性名稱將如何成為魔術字符串,因此我創建了一個非常簡單的方法,如下所示:
public static string GetPropertyName<PropertyType>(Expression<Func<T, PropertyType>> expressionForProperty)
{
MemberExpression expression = expressionForProperty.Body as MemberExpression;
return expression.Member.Name;
}
這讓我可以使用如下代碼:
Product.GetPropertyName(m => m.Name)
返回“名稱”。
這適用於基本對象。 但是,如果我將方法調用更改為:
Product.GetPropertyName(m => m.ProductCategory.Name)
這也返回“名稱”。 但為了使數據綁定工作,我需要它返回“ProductCategory.Name”。 有沒有辦法通過改變方法“GetPropertyName”來達到這個目的?
可能的解決方法是:
string test = Product.GetPropertyName(p => p.ProductCategory) + "." + ProductCategory.GetPropertyName(pc => pc.Name)
但是,這不是一個簡潔的解決方案。
這是我在StackOVerflow上找到的一些修改版本:
public static class GetPropertyNameExtension
{
public static string GetPropertyName<TArg, TProperty>(this Expression<Func<TArg, TProperty>> propertyExpression)
{
return propertyExpression.Body.GetMemberExpression().GetPropertyName();
}
public static string GetPropertyName<TProperty>(this Expression<Func<TProperty>> propertyExpression)
{
return propertyExpression.Body.GetMemberExpression().GetPropertyName();
}
public static string GetPropertyName(this MemberExpression memberExpression)
{
if (memberExpression == null)
{
return null;
}
if (memberExpression.Member.MemberType != MemberTypes.Property)
{
return null;
}
var child = memberExpression.Member.Name;
var parent = GetPropertyName(memberExpression.Expression.GetMemberExpression());
return parent == null ?
child
: parent + "." + child;
}
public static MemberExpression GetMemberExpression(this Expression expression)
{
if (expression is MemberExpression)
return (MemberExpression)expression;
if (expression is UnaryExpression)
return (MemberExpression)((UnaryExpression)expression).Operand;
return null;
}
}
我提出以下似乎有效:
public static string GetComplexPropertyName<PropertyType>(Expression<Func<T, PropertyType>> expressionForProperty)
{
// get the expression body
Expression expressionBody = expressionForProperty.Body as MemberExpression;
string expressionAsString = null;
// all properties bar the root property will be "convert"
switch (expressionBody.NodeType)
{
case ExpressionType.Convert:
case ExpressionType.ConvertChecked:
UnaryExpression unaryExpression = expressionBody as UnaryExpression;
if (unaryExpression != null)
{
expressionAsString = unaryExpression.Operand.ToString();
}
break;
default:
expressionAsString = expressionBody.ToString();
break;
}
// makes ure we have got an expression
if (!String.IsNullOrWhiteSpace(expressionAsString))
{
// we want to get rid of the first operand as it will be the root type, so get the first occurence of "."
int positionOfFirstDot = expressionAsString.IndexOf('.');
if (positionOfFirstDot != -1)
{
return expressionAsString.Substring(positionOfFirstDot + 1, expressionAsString.Length - 1 - positionOfFirstDot);
}
}
return string.Empty;
}
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