how to handle integer or Datetime with Generic List

Question

0.00/5 (No votes)

See more:

I am tring to create dynamic list i want to filter items from list

this function perfectly work with string but other than string like Int32 or DataTime it gives exception

C#

public static List<T> Filter<T>
         (this List<T> source, string columnName,
          string compValue)
     {
         ParameterExpression parameter = Expression.Parameter(typeof(T), "x");
         Expression property = Expression.Property(parameter, columnName);
         Expression constant = Expression.Constant(compValue);
        if (property.Type == typeof(string)) //this is for testing
         {

             Expression<Func<T, bool>> predicate =

                 GetExpression<T>(columnName, compValue);

             Func<T, bool> compiled = predicate.Compile();
             return source.Where(compiled).ToList();
         }


         return null;
     }

static Expression<Func<T, bool>> GetExpression<T>(string propertyName, string propertyValue)
     {
         var parameterExp = Expression.Parameter(typeof(T), "type");
         var propertyExp = Expression.Property(parameterExp, propertyName);
         MethodInfo method = typeof(string).GetMethod("Contains", new[] { typeof(string) });
         var someValue = Expression.Constant(propertyValue, typeof(string));
         var containsMethodExp = Expression.Call(propertyExp, method, someValue); // on this line i am getting error if i remove if condition of type checking

         return Expression.Lambda<Func<T, bool>>(containsMethodExp, parameterExp);
     }

Error

declared on type 'System.String' cannot be called with instance of type 'System.Int32' c#

so i want some function that can handle this issue

actually i tring to create dynamic list for datatable Jquery in mvc
http://www.datatables.net/[^]

i am stuck on one of my column is integer so i am not able to filter on that column
so i am searching

Posted 5-Aug-14 0:47am

Member-515487

Updated 7-Aug-14 0:41am

v3

Add a Solution

Comments

johannesnestler 5-Aug-14 7:25am

Did you read your code? You write: if (property.Type == typeof(string))
and wonder that it just works with strings?.

Member-515487 5-Aug-14 8:21am

yes i know
var containsMethodExp = Expression.Call(propertyExp, method, someValue);
on this line it gives error

johannesnestler 5-Aug-14 8:51am

You wanted to reply to me? - if yes pleas use the reply button, otherwise I don't get informed about your comment. anyway I don't understand what you trying to say (the mentioned line dosn't appear in your code - If you suspect the Problem in the calling code - Show this code! and damn, I say it: If you have the original exception text - then post it!).

Member-515487 7-Aug-14 6:40am

Method 'Boolean Contains(System.String)' declared on type 'System.String' cannot be called with instance of type 'System.Int32'

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Member-515487 · Accepted Answer · 2014-08-07T01:40:00

I change this now it working as expected
for string i want like
other than string i want equal

C#

static Expression<Func<T, bool>> GetExpression<T>(string propertyName, string propertyValue)
    {
        var parameterExp = Expression.Parameter(typeof(T), "type");
        var propertyExp = Expression.Property(parameterExp, propertyName);
        if (propertyExp.Type == typeof(string))
        {
            MethodInfo method = typeof(string).GetMethod("Contains", new[] { typeof(string) });
            var someValue = Expression.Constant(propertyValue, typeof(string));
            var containsMethodExp = Expression.Call(propertyExp, method, someValue);

            return Expression.Lambda<Func<T, bool>>(containsMethodExp, parameterExp);
        }
        else
        {
            var converter = TypeDescriptor.GetConverter(propertyExp.Type);
           var result = converter.ConvertFrom(propertyValue);
            var someValue = Expression.Constant(result);
            var containsMethodExp = Expression.Equal(propertyExp, someValue);
            return Expression.Lambda<Func<T, bool>>(containsMethodExp, parameterExp);
        }
    }