Is there a way to change the connection string of DbContext service in Configure Method after adding it in ConfigureServices method?

Question

I have 2 connection strings in my appsettings.json and I use dbContext.Database.Migrate(); in Configure method to create the database if the primary connection string that I used to create the DbContext service in ConfigureServices method was incorrect, I face Exception so I want to change the connection string of the Dbcontext service in the exception area. How can I achieve that?

I tried to do the migration in ConfigureServices but I don't know how to create a DbContext object and how to test it.

in ConfigureServices

        services.AddDbContext<RedContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

in Configure

        using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
        {
            var dbContext = serviceScope.ServiceProvider.GetService<RedContext>();
            var roleManager = serviceScope.ServiceProvider.GetService<RoleManager<IdentityRole>>();
            var userManager = serviceScope.ServiceProvider.GetService<UserManager<ApplicationUser>>();
            // Create the Db if it doesn't exist and applies any pending migration.
            try
            {
                dbContext.Database.Migrate();// throws exception if CS is wrong
                DbSeeder.Seed(dbContext, roleManager, userManager);
            }
            catch (Exception)
            {                   
                // remove old service and create new dbcontext DI service in IserviceCollection with secondary connection string
                //dbContext.Database.Migrate();
                // dbContext.Database.GetDbConnection()
            }

Did you check this https://stackoverflow.com/questions/40836102/asp-net-core-change-ef-connection-string-when-user-logs-in — SKS, May 13 '19 at 12:34

score 0 · Answer 1 · answered May 13 '19 at 12:20

0

YourDBContextClass dbcontext = new YourDBContextClass("alternateconnectionstringname");

Try this.

P.S Add a cosntructor to your DbContext to do this:

 public partial class YourDBContextClass
 {
    // Add a constructor to allow the connection string name to be changed
 public YourDBContextClass(string connectionStringNameInConfig)
        : base("name=" + connectionStringNameInConfig)
    {
    }
}

answered May 13 '19 at 12:20

vsarunov

1,433
14
26

1

The DbContext class should derive from DbContext and the Constructor doesn't accept strings, it only accepts DbContextOption object. – Habil Harati May 13 '19 at 14:59

score 0 · Answer 2 · answered May 13 '19 at 12:29

I think this will work.

Create a new constructor for your Context

public partial class RedContext
 {
    // Add a constructor to allow the connection string name to be changed
 public RedContext(string connectionStringNameInConfig)
        : base("name=" + connectionStringNameInConfig)
    {
    }
}

Change Configuration:

 using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
        {
            var dbContext = serviceScope.ServiceProvider.GetService<RedContext("alternateconnectionstringname")>();
            var roleManager = serviceScope.ServiceProvider.GetService<RoleManager<IdentityRole>>();
            var userManager = serviceScope.ServiceProvider.GetService<UserManager<ApplicationUser>>();
            // Create the Db if it doesn't exist and applies any pending migration.
            try
            {
                dbContext.Database.Migrate();// throws exception if CS is wrong
                DbSeeder.Seed(dbContext, roleManager, userManager);
            }
            catch (Exception ex)
            {                   
            }
}

It doesn't work because .GetService() accepts only type of objects, not objects like RedContext("CS") . — Habil Harati, May 13 '19 at 15:01

Is there a way to change the connection string of DbContext service in Configure Method after adding it in ConfigureServices method?

2 Answers2