Question

I am trying to build a class that interacts with the database in my asp.net web application. I need your opinion on how to design it, here’s an example of what I have in mind

public class Person
{
    int personId;
    string name;
    string lastName;

    public int PersonId
    {
        get { return personId; }
    }

    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    public string LastName
    {
        get { return lastName; }
        set { lastName = value; }
    }

    public Person()
    {

    }

    public static void Save(Person p)
    {
        //datalayer here
        //save the person class
    }

    public static Person GetPerson(int person_id)
    {
        //datalayer here
        //get the person from database and return a person class
        Person p = new Person();
        p.personId = 10;
        p.name = "Alex";
        return p;
    }
}

So that i can use the database methods without having to instantiate the class:

Person p = Person.GetPerson(19);
p.Name = "Alex...";
Person.Save(p);

I appreciate your help.

Answer 1

Use Automatic proerties because your private fields does the same in your code.

I think, Save is an Operation which can be done on an object of Person Entity. So i wont keep it as a Static method. I would move your Save code as a method of the Person object. So that i will call it like obj.Save(). To load the data, I would use an overloaded version of my class constructor.

public class Person
{
    int personId;      

    public int PersonId
    {
        get { return personId; }
    }    
    public string Name { set;get;}   
    public string LastName { set;get;}        

    public Person() {}

    public Person(int person_id)
    {
        //call to datalayer here
        //get the person from database and return a person class          
        personId = 10;
        Name= "Alex";  // set the public property value here           
    }
    public bool Save()
    {
        //datalayer here
        //save the person class and return
      // true/false /or new ID (change return type)
    }    

}

And when calling,

Person p = new Person(19);  //get existing person
p.Name = "New Name";
p.Save();

EDIT : Another (better) approach is to keep your entity classes as simple POCO’s. that means no data acccess / BL code there. It will simply look like

public class Person
{
  public int ID { set;get;}
  public string Name { set;get;}
}

And have a Repository which does the data operations for you. So your repository may have methods like this

public interface IRepository
{ 
   Person GetPerson(int id);
   bool SavePerson(Person person);
}

You may implement this Interface in a class to do your Data Access operations

public class Repository:IRepository
{
  //implementation of your DA methods here
}

Now you may call it from different layer(business layer) like this

IRepository repo = new Repository();

var person=repo.GetPerson(19);  
person.Name="Updated Name";
repo.Save(person);