Why is this extension method not working?

Question

public static string ToTrimmedString(this DataRow row, string columnName)
{
    return row[columnName].ToString().Trim();
}

Compiles fine but it doesn't show up in intellisense of the DataRow...

Solution 1

My guess is you haven't included the namespace.

Solution 2

Ensure this method is in a static class of its own, separate class from the consuming DataRow.

namespace MyProject.Extensions
{
   public static class DataRowExtensions
   {
      //your extension methods
   }
}

In your consumer, ensure you're:

using MyProject.Extensions

Solution 3

I had this same issue. My mistake wasn't that I missed the static class or static method but that the class my extensions were on was not public.

Comments

[Sanjeevakumar Hiremath]

shows in intellisense in my VS10. just tested it.

[Mike Cole]

Please post the incomplete line where you are trying to call the extension method.

[marc_s]

Also: be careful, if the row doesn't contain any column by the name of columnName you'll end up getting an exception - you might want to check for that and return null or an empty string if that's the case

[Dean Kuga]

@marc_s Absolutely, this was just for simplicity...

[Mustafa Bazghandi]

Extension methods should be define inside a static class.

[Brian]

I don't think it would compile if it weren't in a static class

[Dean Kuga]

using System.Data; is included... Do you think it would compile if using System.Data; was not included?

[gt124]

The namespace of the class that has the extension method.

[Dean Kuga]

that could be it, the class from which I'm trying to use the method is a "sub" namespace of the namespace the extension method is in... will accept if that turns out to be the issue... thanks for clarification...