No database provider has been configured for this DbContext

问题

I recently updated my project to the latest version of Entity Framework Core (+VS2017). When I try to update the DB I get the following error message. The error message is clear, but it appears to be wrong. I do have a AddDbContext in my ConfigureServices (see code below).

What am I missing?

Error

> dotnet ef database update --verbose

Finding DbContext classes...
Using context 'ApplicationDbContext'.

System.InvalidOperationException: 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<TContext> object in its constructor and passes it to the base constructor for DbContext.

Startup

public void ConfigureServices(IServiceCollection services) {
  services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(this.Configuration.GetConnectionString("DefaultConnection")));

CSProj

<PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore">
  <Version>1.1.0</Version>
</PackageReference>
<PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore">
  <Version>1.1.0</Version>
</PackageReference>
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer">
  <Version>1.1.0</Version>
</PackageReference>
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.Design">
  <Version>1.1.0</Version>
  <PrivateAssets>All</PrivateAssets>
</PackageReference>
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools">
  <Version>1.0.0-msbuild1-final</Version>
  <PrivateAssets>All</PrivateAssets>
</PackageReference>
<PackageReference Include="Microsoft.EntityFrameworkCore.Design">
  <Version>1.1.0</Version>
</PackageReference>

回答1:

You have to remove the default constructor.In other words parameter less constructor.After that all will work as expected.

Note : The reason for that is, the parameter less constructor is being called at run time instead of this public MyDbContext(DbContextOptions options) : base(options) {}.

来源：https://stackoverflow.com/questions/40745468/no-database-provider-has-been-configured-for-this-dbcontext

标签

entity-framework

entity-framework-core