Creating dynamic Lambda from Existing Lambda Expression

i have an extension method开发者_运维知识库 that configures the filtering for telerik grid. it receives lambda expressions as parameter. is it possible to make new expressions from existing ones e.g

public static void ConfigureFiltering<T>(this HtmlHelper html, Configurator conf, params Expression<Func<T,object>>[] args) where T:class 
{
 }   

i want to create expressions like

Expression<Func<object,bool?>> filtere = obj=>obj == null? null: obj.ToString().StartsWith("xyz");//return type is nullable cause of string
Expression<Func<object,bool>> filtere = obj=>Convert.ToInt32(obj) < 20 //return type is non-nullable cause of int

can someone plz guide me how to target this problem

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I'm not sure what the problem is that you're having, nor how the first and second parts of your question relate.

I can tell you that the ternary operator in your first expression will need to cast that null to bool?, so it will become:

Expression<Func<object,bool?>> filtere = obj=>obj == null
    ? (bool?)null 
    : obj.ToString().StartsWith("xyz");

Also, both expressions cannot share the same variable name of filtere.

Beyond that, you'll need to explain in somewhat more detail what you are trying to do.