NInject and Migration using EF Core in Console app - .net-core

Question

I am using NInject container for Dependency Injection and Entity Framework Core as ORM. The setup is as follows:
DB Context Class
public TarantoContext()
{
}
public TarantoContext(DbContextOptions<TarantoContext> options)
: base(options)
{
}
public virtual DbSet<FileData> FileData { get; set; }
public virtual DbSet<FileExport> FileExport { get; set; }
public virtual DbSet<FileStatus> FileStatus { get; set; }
public virtual DbSet<FileType> FileType { get; set; }
public static string ConnectionString { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
if (!optionsBuilder.IsConfigured)
{
optionsBuilder.UseSqlServer(ConnectionString);
}
}
Program.cs
TarantoContext.ConnectionString = configurationManager.DatabaseConnection;
I am reading the configuration from json and passing it to the DataAccess layer (to the context class). I have a few tables in my database and taking database first approach I created the necessary data models and completed the dbcontext class code. I am able to fetch the data without any problems. Now I want to add-migration (I may have more changes to existing tables and may create new tables) and ran the following in package manager console:
Add-Migration InitialCreate
which resulted in the following error because the connectionstring property is null
I can fix this by hardcoding the connectionstring in the OnConfiguring method which I have tried without any problems:
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
if (!optionsBuilder.IsConfigured)
{
// The connection string needs to exist in the migration project for the purpose of migrations. Comment it in production.
optionsBuilder.UseSqlServer(
"Data Source=temp;Initial Catalog=Demo;Persist Security Info=True;User ID=temp;Password=temp;MultipleActiveResultSets=True;");
//optionsBuilder.UseSqlServer(ConnectionString);
}
}
but I do not think this is the correct way of doing migrations. Moreover I am not sure how to handle the migrations in productions if I am unable to set the connectionstring in Program.cs or outside of the dbcontext class. What I am interested in is learning any design pattern which other developers are using to handle this situation. Any advise is greatly appreciated.

Answer 1

In ASP.NET Core, you can load the connection string while setting up services in the ConfigureServices method. Use the following code:
services.AddDbContext<ApplicationDatabaseContext>(options =>
options.UseSqlServer(
Configuration.GetConnectionString("DefaultConnection"),
b => b.MigrationsAssembly("....")));
Now, the GetConnectionString call will retrieve the connection string from you configuration file i.e. appsettings.json. To handle different connection strings for different environments, you can override the default app settings using a appsettings.<Environment>.json file like appsettings.Production.json.
More on this here: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/environments?view=aspnetcore-2.2
Check out the relevant MSDN documentation pages for these things as they contain a lot of information.