error trying to use EF core code first

Question

User1571524970 posted

I am trying to use entity framework core code first, with an external sql server database hosted on AWS RDS. My aim is for EF to create my model database/tables automatically the first time I use Swagger to create an object. Currently, I am trying to enable migrations for my project before I allow EF code first to create the databases. Although when I try to Enable-Migrations I get an error: "The context type 'FitnessTrackerAPIContext' was not found in the assembly 'FitnessTrackerAPI'." As you can see from the below picture, the 'FitnessTrackerAPIContext' is in the 'FitnessTrackerAPI' so I am not sure why I am getting this error.

I am not quite sure if all my settings for EF core are correct s this is my first time using it.

Context:

namespace FitnessTrackerAPI.Data
{
    public class FitnessTrackerAPIContext : DbContext
    {
        public FitnessTrackerAPIContext (DbContextOptions<FitnessTrackerAPIContext> options)
            : base(options)
        {
        }

        public DbSet<FitnessTracker.UserData> Users { get; set; }

        public DbSet<FitnessTracker.WorkoutData> Workouts { get; set; }
    }
}

I have added the following to Startup.cs:

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

My connection string in appsettings.json:

 "ConnectionStrings": {
    "FitnessTrackerAPIContext": "Server=fitnessapi.clxnbxbuoxx1.eu-west-1.rds.amazonaws.com,1433;User ID=XXXXX;Password=XXXXX; Initial Catalog=fitnessapi; Database=fitnessapi; Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"

Do I need to add any other code? In program.cs or so? This is program.cs currently:

namespace FitnessTrackerAPI
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

Any advice would be appreciated.

Answer 1

User475983607 posted

darego

Do I need to add any other code? In program.cs or so?

Yes, you need to add code to invoke pending migrations.

        private void InitializeDatabase(IApplicationBuilder app)
        {
            using (var serviceScope = app.ApplicationServices.GetService<IServiceScopeFactory>().CreateScope())
            {
                var context = serviceScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
                context.Database.Migrate();

            }
        }

Call the method from startup.cs.

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //Apply pending migrations
            InitializeDatabase(app);

This configuration causes migrations to run when the application starts.

Answer 2

User1571524970 posted

Thanks a lot mgerbhard. Can I confirm, I need InitializeDatabase() in the program.cs file outside of Main, and call it  from Startup.cs in Configure? e.g.

Startup.cs

 // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //Apply pending migrations
            InitializeDatabase(app);

Program.cs

public class Program
    {
        public static void Main(string[] args)
        {

            CreateHostBuilder(args).Build().Run();
        }

        private void InitializeDatabase(IApplicationBuilder app)
        {
            using (var serviceScope = app.ApplicationServices.GetService<IServiceScopeFactory>().CreateScope())
            {
                var context = serviceScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
                context.Database.Migrate();

            }
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }

Answer 3

User1571524970 posted

it seems to be working now; i put the InitializeDatabase() method above the Configure() method in Startup.cs

 private void InitializeDatabase(IApplicationBuilder app)
        {
            using (var serviceScope = app.ApplicationServices.GetService<IServiceScopeFactory>().CreateScope())
            {
                var context = serviceScope.ServiceProvider.GetRequiredService<FitnessTrackerAPIContext>();
                context.Database.Migrate();
            }
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //Apply pending migrations
            InitializeDatabase(app);

Shouldn't EF code first create my tables now when I try access the API? I used swagger to post an object to the API and got the following 500 server error:

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details.
 ---> Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid object name 'Users'.

It seems like EF isn't automatically creating my tables. fitnessapi database has no tables:

Answer 4

User711641945 posted

Hi darego,

It seems like EF isn't automatically creating my tables. fitnessapi database has no tables:

That is because you do not have migration file in your project.

A simple way is to run the command on PMC(Package Manager Console):

PM>add-migration init

Then you could run the app by using your code(InitializeDatabase(app)) to apply the migration,or run the following command which could also apply the migration:

PM>update-database

Reference:

https://docs.microsoft.com/en-us/ef/core/managing-schemas/migrations/?tabs=vs

Best Regards,

Rena