How can I force "update-database" when Asp.Net site starts

Question

Background

I am working on an existing Asp.Net site that uses Database Migrations and Asp.Net Identity.

The site has a folder "Migrations", with a few database migrations. A while ago, I created a "Seed_Only"-migration that doesn't do anything, but simply - as the name implies - executes the Seed method when called thus:

Update-Database -TargetMigration SeedOnly

Irrelevant of whether it's good practice or not, the Seed method creates new roles if the static helper class RolesName contains any new roles:

// Iterate all properties of RolesName and create roles if they don't exist
Type type = typeof(RolesName); 
foreach (var p in type.GetFields())
{
    var v = p.GetValue(null).ToString(); // static classes cannot be instanced, so use null...
    if (!context.Roles.Any(x => x.Name.Equals(v)))
    {
        roleManager.Create(new IdentityRole() { Name = v });
    }
}

The Question

We are about to introduce a couple of new roles. I want to make sure each site that runs the app gets it's database updated upon deploy (we deploy using Octopus).

Goals

The following should happen:

Create new roles if they don't already exist
Add the new roles to existing users - if the users are member of a previously existing role

This related answer suggests I call Database.SetInitializer(new ApplicationDbInitializer()); from the Constructor of ApplicationDbContext. If I understand the answer correctly, this would solve my need to "continuously keeping the roles up to date", but it does not solve my need for adding existing users to the new roles, as stated in point 2.

How should I go about to achieve my goals?

score 0 · Accepted Answer · answered May 28 '18 at 05:56

I ended up using the solution suggested here. It consists of:

1. A static class that creates the data needed

public static class LocatorInitializationHandler
{
    public static void Initialize()
    {
        using (var db = new ApplicationDbContext())
        {
            CreateRoles(db);
        }
    }

    private static void CreateRoles(ApplicationDbContext context)
    {
        // iterate role names
        // and insert into db if not already exists
    }
}

2. Call the static class from global.asax.cs

protected void Application_Start()
{
    // Initialize database
    LocatorInitializationHandler.Initialize();
}

How can I force "update-database" when Asp.Net site starts

1 Answers1