EF Core 2.1 - No database provider has been configured for this DbContext

Question

I have ASP.Net Core 2.1 with EF Core 2.1. This is how my DbContext class looks like

app.DAL.EF -> Layer

using app.domain;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using Microsoft.Extensions.Configuration;
using System;
using System.IO;

namespace app.EF
{
 public class MyAppContext : DbContext
 {
    public MyAppContext(DbContextOptions<MyAppContext> options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfiguration(new CustomerConfiguration());
        modelBuilder.HasDefaultSchema("app");
        base.OnModelCreating(modelBuilder);
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);
    }

    public DbSet<Customer> Customers { get; set; }
 }

   public class MyAppContextConfiguration : IDesignTimeDbContextFactory<MyAppContext>
   {
    public MyAppContext CreateDbContext(string[] args)
    {
        IConfigurationRoot configuration = new ConfigurationBuilder()
                                            .SetBasePath(Directory.GetCurrentDirectory())
                                            .AddJsonFile("appsettings.json", optional: false, true)
                                            .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT ") ?? "Production" }.json", optional: true)
                                            .Build();

        var optionsBuilder = new DbContextOptionsBuilder<MyAppContext>();
        //optionsBuilder.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
        var dbConString = configuration.GetConnectionString("ITMDbConnection");

        optionsBuilder.UseSqlServer(dbConString);

        return new MyAppContext(optionsBuilder.Options);
    }
}

public class CustomerConfiguration : IEntityTypeConfiguration<Customer>
{
    public void Configure(EntityTypeBuilder<Customer> builder)
    {
        builder.HasKey(x => x.Id);
    }
}}

app.DI -> Layer

  public static class Factory
  {
    public static void Initialize(ref IServiceCollection services)
    {
        //services.AddTransient<MyAppContext>();
        services.AddDbContext<MyAppContext>(options =>
        {

        });
        //services.AddTransient<MyAppContextConfiguration>();
        services.AddTransient<ICustomerRepository, CustomerRepository>();
    }
}

app.API -> Layer

 namespace app.api
 {
 public class Startup
 {
     public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        Factory.Initialize(ref services);
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseMvc();
    }
}}

When running Add-Migration DbInit from Package Manager Console, throwing the below error

No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions object in its constructor and passes it to the base constructor for DbContext.

Thanks!

The error message is pretty clear. What database is this supposed to use? Oracle, PostgreSQL, MySQL? Where will it connect to? A local database, a remote one, AWS RDS? You need to specify the provider and connection inside AddDbContext. Which, btw, should be in Startup.cs. Those methods are DI configuration methods, not factories or layers. If you want to simplify your code you could create an extension method that receives and returns an IServiceCollection, alowing you to chain config calls just like other DI config methods — Panagiotis Kanavos
@PanagiotisKanavos Isn't the same mentioned in MyAppContextConfiguration class? — Kgn-web
You aren't using CreateDbContext anywhere. This code is a bit overcomplicated. Those classes, methods aren't layers, they are just a DbContext and some startup config methods. The DbContext configuration and DI registration is performed by AddDbContext. A simple options.UseSqlServer(Configuration.GetConnectionString("ITMDbConnection")) in there would work. The MyAppContextConfiguration class isn't used anywhere in Startup.cs — Panagiotis Kanavos
The host builder in ASP.NET Core 2.x and 3.x already perform the config steps in CreateDbContext - load appsettings.json, any environment files etc. This means that the Configuration field in Startup.cs can load the connection strings — Panagiotis Kanavos
if I use this options.UseSqlServer() in Factory or Startup class. Then tight coupling is being introduced — Kgn-web

TomTom TomTom · Accepted Answer · 2020-03-04T08:43:34

it is easactly what it says - there is no database provider attached.

Look at all your code. Where do you specify the database provider? Something like UseSqlServer (in OnConfiguring of the DbContext), depending on what database provider you want to use.

EF Core 2.1 - No database provider has been configured for this DbContext

3 Answers