Efcore: Named connection strings are only supported when using 'IConfiguration' and a service provider

[mucciols]

could you please tel me what i am doing wrong?

SCAFOLD DBCONTEXT

Scaffold-DbContext -Connection name=DbAsp Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -f

CONFIGURESERVICES
```C#
public void ConfigureServices(IServiceCollection services)
{
services.Configure(options =>
{
// This lambda determines whether user consent for non-essential cookies is needed for a given request.
options.CheckConsentNeeded = context => true;
options.MinimumSameSitePolicy = SameSiteMode.None;
});

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

        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
    }

ASPCONTEXT.CS
```C#
public partial class aspContext : DbContext
    {
        public aspContext()
        {
        }

        public aspContext(DbContextOptions<aspContext> options)
            : base(options)
        {
        }

        ...
}

EXCEPTION

InvalidOperationException: A named connection string was used, but the name 'DbAsp' was not found in the application's configuration. Note that named connection strings are only supported when using 'IConfiguration' and a service provider, such as in a typical ASP.NET Core application. See https://go.microsoft.com/fwlink/?linkid=850912 for more information.

APPSETTINGS.JSON

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },

  "AllowedHosts": "*",

  "ConnectionStrings": {
    "DbAsp": "Server=xxx;Database=xyz;integrated security=True;"
  }
}

Exception message:
Stack trace:
A named connection string was used, but the name 'DbAsp' was not found in the application's configuration. Note that named connection strings are only supported when using 'IConfiguration' and a service provider, such as in a typical ASP.NET Core application. See https://go.microsoft.com/fwlink/?linkid=850912 for more information

Further technical details

EF Core version: (found in project.csproj or packages.config)
Database Provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer)
Operating system:
IDE: (e.g. Visual Studio 15.7.2)
.NET CORE 2.2 release 3

[ajcvickers]

@mucciols We have not been able to reproduce this. Can you post a runnable project/solution or complete code listing that demonstrates the issue you are seeing.

[mucciols]

Hi, thank you for your reply. Now i have injected the dbcontext in the constructor and Now it work.
Best wishes.
Simone

[rahul-uttarkar]

We are still facing these issue in dotnetcore console application.

Steps to reproduce:
Create console app ( core 2.1) (I have not did any modification to default created project)
Add Entity frameworks from package-manager console
Use database first approach
Scaffold-DbContext -Connection name=DbAsp Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -f

We are getting this same error as soon as we run this command.
.

[ajcvickers]

@drua By default, a console application created in Visual Studio or by dotnet doesn't have any EF code, so when you say that you did not make any modifications to the default created project, that doesn't seem to align with the exception you are seeing. Given this, I think I am misunderstanding what you mean by "default console app". Can you post the "default console app" that you created so we can take a look, and also be specific about how/where it was created.

[weirdyang]

Is there a workaround for this if I wish to use EF Core in a separate .NET standard class library?

My current project structure is like this:

EFCore.Library (.NET standard class library)
-Models
-Data

DummyStartUp (console application)
Program.cs

Scaffold-DbContext -Connection name=DefaultConnection -OutputDir Models -ContextDir Data Microsoft.EntityFrameworkCore.SqlServer -Context UEIOSContext -Project DummyStartup -StartupProject DummyStartup -Force

ERROR
A named connection string was used, but the name 'DefaultConnection' was not found in the application's configuration. Note that named connection strings are only supported when using 'IConfiguration' and a service provider, such as in a typical ASP.NET Core application. See https://go.microsoft.com/fwlink/?linkid=850912 for more information.

I want to use a named connection string to avoid the connection string being written into the dbcontext file. https://github.com/aspnet/EntityFrameworkCore/issues/10432

I've tried adding this to my dummy startup project program.cs, but no luck:

```
internal class Program
{
private static void Main(string[] args)
{

        IConfigurationRoot configuration = new Microsoft.Extensions.Configuration.ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddUserSecrets(typeof(Program).GetTypeInfo().Assembly)
            .Build();
        IServiceCollection services = new ServiceCollection();


        services.AddLogging(options =>
        {
            options.AddDebug();
            options.AddConsole();
        }
        );
    }
}```

[ajcvickers]

@captmomo It should be possible to wire up everything to make this work outside of an ASP.NET Core application, but I doubt it would be worth it. Instead just use whatever mechanism works for you to load the connection string from wherever you have it stored, and then pass it to EF.

[weirdyang]

@ajcvickers thanks. I ended up using a dummy mvc project instead and it worked as expected

[sibeliuz]

Still does not work in .net core 3.xx web api projects

[BlackMush]

@sibeliuz Same here, I couldn't manage to make this work in my web API 3.0 project. I tried with a brand new Web API solution, created with VS 2019, it still doesn't work.

[weirdyang]

The main thing is to have your web api project reference the class library and Ensure you have a named connectionstring for your web api project. I have used this method for both .net core 3* and 2* projects.

[BlackMush]

@captmomo I'm not sure to understand what you mean by "to have your web api project reference the class library"
Do you mean this (in Startup.cs) :
services.AddDbContext<TradeoDataContext>(x => x.UseSqlServer(Configuration.GetConnectionString("TradeoConnectionString")));
And this, in appSettings.json :
"ConnectionStrings": { "TradeoConnectionString": "Server=xxx;Database=Tradeo;Trusted_Connection=False; User Id=xxx; Password=xxx" },

[weirdyang]

No. Right click the web project, select add reference, select the projects
tab, select your class library project

Scaffold-DbContext -Connection name=DefaultConnection -OutputDir Models -ContextDir Data Microsoft.EntityFrameworkCore.SqlServer -Context TradeoContext -Project MyClassLibrary -StartupProject DummyStartup -Force

Replace MyClassLibrary with the name of your class library
Replace DummyStartup with the name of your web api project
Replace default connection with the name of your connection string
Ensure there’re a named connection string in the appsettings of your web api project
to clarify, my previous instructions is for the instance where you wish to have your EF Core stuff in a separate .NET standard library.

On Thu, 6 Feb 2020 at 7:37 PM, BlackMush [e-mail] wrote:

@captmomo https://github.com/captmomo I'm not sure to understand what
you mean by "to have your web api project reference the class library"
Do you mean this (in Startup.cs) :
services.AddDbContext(x =>
x.UseSqlServer(Configuration.GetConnectionString("TradeoConnectionString")));
And this, in appSettings.json :
"ConnectionStrings": { "TradeoConnectionString":
"Server=xxx;Database=Tradeo;Trusted_Connection=False; User Id=xxx;
Password=xxx" },

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[BlackMush]

Okay, thanks for the clarification. I didn't figure out you were talking about your previous comments. I'll try that, but that's only a workaround. Maybe I should re-open an issue, I reproduced the problem very easily on a new solution.

[weirdyang]

Ok now I’m confused
What exactly is the issue you’re facing ?

On Thu, 6 Feb 2020 at 9:45 PM, BlackMush [e-mail] wrote:

Okay, thanks for the clarification. I didn't figure out you were talking
about your previous comments. I'll try that, but that's only a workaround.
Maybe I should re-open an issue, I reproduced the problem very easily on a
new solution.

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[BlackMush]

Very precisely the one described in the first comment :)

[weirdyang]

Very precisely the one described in the first comment :)

** to clarify, my previous instructions is for the instance where you wish to have your EF Core stuff in a separate .NET standard library.
Can you post the solution that you created so we can take a look, and also be specific about how/where it was created. And the command you used?

@BlackMush fwiw, I also tried what the first comment said, and I couldn't reproduce it. I could attach my project for your reference if it helps.

[BlackMush]

I could attach my project for your reference if it helps.

I believe you, I cannot reproduce the problem on the new solution anymore ! It's still not working on my real API project though. I'll definitely try your solution.

Thanks for your time 👍

[zanyar3]

Details

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
               // add IConfigurationRoot  to get connection string 
                IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(AppDomain.CurrentDomain.BaseDirectory)
                .AddJsonFile("appsettings.json")
                .Build();
                optionsBuilder.UseSqlServer(configuration.GetConnectionString("DefaultConnection"), x => x.UseNetTopologySuite());
            }
        }

[mmu69]

I had this problem with a new Core 3.1 project and a Scaffold-DbContext. Startup.cs has a IConfiguration.
Adding the DdContext to startup.cs solved the problem

    public void ConfigureServices(IServiceCollection services)
    {
        ........
        services.AddDbContext<StipContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("StipDatabase")));
    }

[Yan9080]

I had this problem with a new Core 3.1 project and a Scaffold-DbContext. Startup.cs has a IConfiguration.
Adding the DdContext to startup.cs solved the problem

    public void ConfigureServices(IServiceCollection services)
    {
        ........
        services.AddDbContext<StipContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("NameOfYourConnectionStringParameter")));
    }

Yes, that's the correct answer.
When we use connectionstring as a parameter inside "appsettings.json" file, then we need to add that code to specify the connectionstring parameter name