CODEWITHSUNDEEP
c#entity-framework-coreef-fluent-api
el ahmadi
el ahmadi

Reputation: 59

CS0311 C# The type cannot be used as type parameter 'TContext' in the generic type or method. EntityFrameworkCore

I specify the context class I created in the entity project on the Startup.cs file and the connectionString data I created for connectionString. But why am I getting this error?

ERROR message: Severity Code Description Project File Line Suppression State Error CS0311 The type 'Microsoft.ApplicationInsights.Extensibility.Implementation.UserContext' cannot be used as type parameter 'TContext' in the generic type or method 'EntityFrameworkServiceCollectionExtensions.AddDbContext(IServiceCollection, Action, ServiceLifetime, ServiceLifetime)'. There is no implicit reference conversion from 'Microsoft.ApplicationInsights.Extensibility.Implementation.UserContext' to 'Microsoft.EntityFrameworkCore.DbContext'. EntityFramework2 C:\Users\xsamu\source\repos\EntityFramework2\EntityFramework2\Startup.cs 29 Active

Startup class:

namespace EntityFramework2
{
    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)
        {
            services.AddControllersWithViews();
            services.AddDbContext<UserContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DevConnection")));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

Entity configuration:

namespace EntityFramework2
{
    public class EntityConfiguration : IEntityTypeConfiguration<User>
    {
        public void Configure(EntityTypeBuilder<User> builder)
        {
            builder.HasOne<Department>(navigationExpression: s => s.Name)
                .WithOne(sa => sa.User)
                .HasForeignKey<Department>(sa => sa.DepartmentId);

            builder.HasOne<Title>(navigationExpression: s => s.TitleCode)
               .WithOne(sa => sa.User)
               .HasForeignKey<Title>(sa => sa.TitleId);

            builder.HasOne<Position>(navigationExpression: s => s.PositionCode)
               .WithOne(sa => sa.User)
               .HasForeignKey<Position>(sa => sa.PositionId);
        }
    }
}

Upvotes: 5

Views: 30216

Answers (7)

Gabriel Silva
Gabriel Silva

Reputation: 73

This problem happens because of the DbContext inheritance, I had the same problem while I was inheriting from IdentityDbcontext because it was inheriting and old package.

I solved adding this package: Microsoft.AspNetCore.Identity.EntityFrameworkCore

FYI: IdentityDbcontext also inherits from DbContext.

Upvotes: 0

Himadrish Laha
Himadrish Laha

Reputation: 1

I faced similar issues in configuartion class. Earlier, the code was placed as DbMigrationsConfiguration<UserContext>. However reviewing the error below, the code has been updated and the error gone.

Error CS0311 The type 'EntityFramework2.Data.UserContext' cannot be used as type parameter 'TContext' in the generic type or method 'DbMigrationsConfiguration'. There is no implicit reference conversion from 'EntityFramework2.Data.UserContext' to 'System.Data.Entity.DbContext'.

Updated Code:

internal sealed class Configuration : DbMigrationsConfiguration<DbContext>

Upvotes: -2

Bogdan Shahnitsky
Bogdan Shahnitsky

Reputation: 792

Entity Framework requires You to inherit Your UserContext from the DbContext EFCore's base class. Please double-check if you really did this (judging by the error message, you forgot about it).

Upvotes: 3

Nathaniel Hibbler
Nathaniel Hibbler

Reputation: 195

You get this message when you have a call and its interface but you forgot to let the class implement the interface.

class UserContext : MyInterface

Upvotes: 1

Okelue Lazarus
Okelue Lazarus

Reputation: 21

check your nuget package you install Microsoft.AspNet.Identity.EntityFrameworkCore instead of Microsoft.AspNetCore.Identity.EntityFrameworkCore;

AspNet instead of AspNetCore

that should do it

Upvotes: 1

Abdessamad Jadid
Abdessamad Jadid

Reputation: 401

Just make Your Context UserContext inherited from DbContext Class like the following Code and you are good to go:

public class UserContext : DbContext
{
    public UserContext (DbContextOptions<UserContext > options)
        : base(options)
    { }

    public DbSet<User> Users{ get; set; }
}

Upvotes: 0

lauxjpn
lauxjpn

Reputation: 5254

There is no implicit reference conversion from 'Microsoft.ApplicationInsights.Extensibility.Implementation.UserContext' to 'Microsoft.EntityFrameworkCore.DbContext'.

The message tells you, that your UserContext class does not inherit from DbContext, which is mandatory.

It should look something like this:

public class BloggingContext : DbContext
{
    public BloggingContext(DbContextOptions<BloggingContext> options)
        : base(options)
    { }

    public DbSet<Blog> Blogs { get; set; }
}

For further information, see the EF Core Tutorial and Configuring a DbContext.

Upvotes: 9

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