How to reference a class in ASP.NET - asp.net

Question

I created a website and would like to have a class to centralize all the code that I use frequently in the entire project, for instance, a method to connect to the database. Question: after I create this class, on the App_Code folder, how can I use it in the aspx.cs pages? I mean, should a reference it? Should I inform add a namespace?
Thanks!

Answer 1

Create the class file as public and you will be able to access the class file at any part of your project.
namespace applicationName
{
public class DataManager
{
public static DataTable GetData(StringBuilder sql)
{
}
}
}
you can access the DataManager from your code.
DataManager.GetData(SQL);

Answer 2

Yes, put your class in a namespace and consider making the class static if possible, that way it can be used in code throughout your project without instantiating the class. This is common for utility classes that pass in objects and do work with them, but do not need the actual utility method to be part of a class instance.
For example:
namespace My.Utilities
{
public class static ConnectionStringHelper
{
public static string GetConnectionString()
{
// Logic here to actually get connection string
return yourConnectionString;
}
}
}
Now, code in your project just needs to reference the My.Utilities namespace and then can use the GetConnectionString() method, like this:
using My.Utilities;
string connString = ConnectionStringHelper.GetConnectionString();

Answer 3

You can do it a number of ways. Technically you can drop the namespace completely and your code becomes a free for all (accessible from anywhere naturally). I prefer to use namespaces personally, but I have seem people just avoid them.
If your class Foo is in Some.Namespace, you can reference it as such:
Way one:
Some.Namespace.Foo foo = new Some.Namespace.Foo()
Way two: Use the "Use" command
If your class is inside of Some.Namespace and you don't want all the junk preceding your class name, you can add:
using Some.Namespace;
to the top of your file.
I may be miss understanding what you are saying. If you are talking about setup, you can make a centralized class that manages everything. This class can be a singliton. For instance:
class MyClass
{
public static MyClas Singliton;
static MyClass()
{
Singliton = new MyClass();
}
public void someFunction()
{
}
}
This will create and manage a single reference to your class so that everything is managed out of there (hence being called a "singleton"). As a result, you can access it by:
MyClass.Singliton.someFunction();
There are ways to protect your singliton instance from being overwritten, but this is the basic idea. If you want to manage stuff out of a single location without recreating classes, singletons are the way!
http://msdn.microsoft.com/en-us/library/ff650316.aspx

Answer 4

If the class is wrapped in a namespace, then yes, you'll need a using statement that matches your namespace. For instance, if your class is wrapped in a namespace like so:
namespace My.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
then anywhere you want to use that class you'll need to add
using My.Namespace;
to the top of the files where you want to utilize the class(es) you've defined. Then you can use your class as you would expect:
Foo foo = new Foo(); //for a new instance
Foo.Bar(); //for a static method
This is, of course, assuming that the class is in the same assembly and you don't want to mess with adding it to the GAC.
Alternatively, if for some reason you don't to use a using statement you can use the fully qualified name of the class:
My.Namespace.Foo foo = new My.Namespace.Foo(); //for a new instance
My.Namespace.Foo.Bar(); //for a static method
This is most useful if you have namespaces that conflict, for instance if you had
namespace My.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
somewhere, and
namespace MyOther.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
somewhere else, but needed to use them both in the same scope.