使用反射来物业名称获得拉姆达前pression [英] Use reflection to get lambda expression from property Name

问题描述

我想给用户通过不同的属性搜索的选择。例如

I want to give the user the choice of searching by different properties. For instance

[输入文本] | [选择选项{ID，姓名，电话}] | [SEARCH]

[INPUT TEXT] | [SELECT OPTION {ID, NAME, PHONE}] | [SEARCH]

和我以后会建立我的查询是这样的：

And I would later build my query like this:

repository.Where(lambda-expression)

其中的λ-EX pression从所选的选项，打造{ID，姓名，电话}
（例如：X => x.NAME.Equals（输入文本））

Where lambda-expression is build from the selected option {ID, NAME, PHONE} (For example: x => x.NAME.Equals(INPUT TEXT))

有没有建在属性名拉姆达可能使用反射的方式？

Is there a way to build the lambda from the Property name perhaps using reflection?

感谢

推荐答案

您不建立一个lambda前pression - 您打造一个前pression树。这是不是非常难，但需要一点耐心。在您的样品你可能需要：

You don't build a lambda expression - you build an expression tree. It's not terribly hard, but it takes a little patience. In your sample you'd probably need:

ParameterExpression parameter = Expression.Parameter(typeof(Foo), "x");
Expression property = Expression.Property(parameter, propertyName);
Expression target = Expression.Constant(inputText);
Expression equalsMethod = Expression.Call(property, "Equals", null, target);
Expression<Func<Foo, bool>> lambda =
   Expression.Lambda<Func<Foo, bool>>(equalsMethod, parameter); 

这是假设：

• 存储库元素类型是富


• 您想使用一个名为属性 propertyName的


• 您想比较反对的inputText 平等

• The repository element type is Foo
• You want to use a property called propertyName
• You want to compare for equality against inputText

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