how to modify a DbSet at an specific time? - asp.net-mvc

Question

I am working on an ASP NET MVC 5 website and I want to modify an element of a DbSet only once at the start of a new day, month and year, but I can't find any example on the internet doing this, any help on how to do this?
lets say I have:
public class File
{
public int FileID { get; set; }
public int Votes { get; set; }
}
and
public DbSet<File> Files { get; set; }
and I want to change a file votes to 0 at the start of a new day only once:
var modFile = new File{ FileID = 2, Votes = 0};
db.Entry(modFile).State = EntityState.Modified;
db.SaveChanges();
Where in a MVC 5 project do I put this code?
How it gets triggered?

Answer 1

If you have an external Service layer (that is independent of .NET) which contains your objects (in your case, File.cs, etc..) then using the built-in Windows scheduler is fine (it triggers executable code at a certain time, as defined by the user).
To do this, you may want to create a Console Application that has a reference to the Service dll and the connection of your database.
Console Application
In Visual Studio, go to File -> New Project -> Visual C# -> Console Application.
Within the App.config file, you can add the connection string to your database. For example:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
<add name="SchoolDBConnectionString"
connectionString="Data Source=...;Initial Catalog=...;Integrated Security=true"
providerName="System.Data.SqlClient"/>
</connectionStrings>
</configuration>
You can then set up a reference to your Service.dll which should have the database context accessible, e.g. DataContext db = MyService.Data.DataContext();
So instead of:
var modFile = new File{ FileID = 2, Votes = 0};
db.Entry(modFile).State = EntityState.Modified;
db.SaveChanges();
You could use:
db.Files.Where(s => s.Votes > 0).ToList().ForEach(s => s.Votes = 0);
db.SavesChanges();
You can run the project in release mode and grab the relevant dll's and exe file. Within the Task Scheduler you are then able to create a task that runs a specific exe.
Service
Technically speaking, you don't have to have this level of isolation -- but in my opinion it's good practice. You could just create a reference to your MVC project, but I personally wouldn't.
To create a Service layer..
Right click your solution (where your MVC application is within) -> Add -> New Project -> Visual C# -> Class Library
Within this project, you should move all your objects (File.cs, etc) within here. You are then able to create a reference to this project within your MVC project by right clicking References and selecting the Service library you just created. You can do the same for the Console Application.
This will then create a layer of isolation between your MVC application and concrete (business) logic.
Otherwise, if you have to schedule your tasks within ASP.NET check out Scott Hanselman's post -- he has compiled together a list of libraries that schedule jobs at certain times. It's however important to understand that ASP.NET applications should only really deal with user requests and responses - threads are somewhat dangerous.