how to update .edmx file without effecting all the other model classes? - entity-framework

Question

how to update .edmx file without effecting all the other model classes?
when I update the edmx file it recreates all the other classes and this is a problem for me because I made some changes on the other classes so how can I modify it without affecting the other classes.
For example this is one of my classes
public partial class company
{
public company()
{
this.Departments = new HashSet<department>();
this.CustomersOfTheCompany = new HashSet<company_customers>();
this.CompaniesTheCompanyCustomerFor = new HashSet<company_customers>();
this.CustomerProjectDetails = new HashSet<cus_pro_connector>();
this.CompanyAsSupplier = new HashSet<company_suppliers>();
this.CompanyAsCustomer = new HashSet<company_suppliers>();
this.Tickets = new HashSet<oneTimeAuthenticationTicket>();
}
[Required(ErrorMessage = "Company name is required")]
[StringLength(200, MinimumLength = 3, ErrorMessage = "Length Of The Company Name Should Be More Than Three Letters")]
public string CompanyName { get; set; }
[Required]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }
[Required]
public int Country { get; set; }
public int company_id { get; set; }
public string Logo { get; set; }
public string Description { get; set; }
private CompanyDTO _CDTO = new CompanyDTO();
public CompanyDTO CDTO { get { return this._CDTO; } set { this._CDTO = value; } }
public virtual ICollection<department> Departments { get; set; }
public virtual country CountryOfTheCompany { get; set; }
public virtual ICollection<company_customers> CustomersOfTheCompany { get; set; }
public virtual ICollection<company_customers> CompaniesTheCompanyCustomerFor { get; set; }
public virtual ICollection<cus_pro_connector> CustomerProjectDetails { get; set; }
public virtual ICollection<company_suppliers> CompanyAsSupplier { get; set; }
public virtual ICollection<company_suppliers> CompanyAsCustomer { get; set; }
public virtual ICollection<oneTimeAuthenticationTicket> Tickets { get; set; }
}
so when I modify the .edmx the class attributes will no longer be available.

Answer 1

It is not possible to retain edits to generated files when you re-generate them. If you need to apply attributes to generated code, there is a MetadataType mechanism that allows you to specify validation attributes in another partial class.
See this other answer or MSDN for further information on this.

Answer 2

I don't understand your example - But I will explain here:
Let's say you have the following Entity Models:
And the User.cs looks like this:
public partial class User
{
public User()
{
this.UserWindows = new HashSet<UserWindow>();
}
public int UserId { get; set; }
public string UserName { get; set; }
public string Password { get; set; }
public virtual ICollection<UserWindow> UserWindows { get; set; }
}
Add a new file and call it Extensions.cs, then create a New Partial Class in this File:
Then you can Add Properties to this Class:
public partial class User
{
public int NewUserId { get; set; }
}
And whenever you create a New User Object you will see your new Properties:
Similarly you can do this for UserWindow.cs
Extensions.cs:
public partial class User
{
public int NewUserId { get; set; }
}
// Similarly you can do
public partial class UserWindow
{
public string MyNewProperty { get; set; }
}
Then