How to get settings from appsettings.json in a referenced .NET Framework project

.net-core entity-framework-6

Question

I've got a DAL with EntityFramework 6 running in .NET Framework 4.6.1 as a project. Works fine in solutions with other .NET Framework projects. Now am I going to use same DAL project referenced to my ASP.NET Core WebApi (using .NET Framework 4.6.1) and it doesn't work. The exception says:

No connection string named 'MyEntities' could be found in the application config file.

.NET Core project does not hava a web.config file, so EF6 How can I pass settings from appsettings.json in my Core project to the referenced DAL project?

I've found some examples to get EF6 working inside .NET Core projects (like https://docs.microsoft.com/en-us/aspnet/core/data/entity-framework-6), but it doesn't help me. I guess that's becouse the dbcontext is created inside the DAL project.

appsettings.json

"ConnectionStrings": {
  "MyEntities": "<my connectionString>"
},

project.json

"dependencies": {
  "EntityFramework": "6.1.3",
  ...
},
...
"frameworks": {
  "net461": {
    "dependencies": {
      "DAL": {
        "target": "project"
      }
    },
    "imports": "dnxcore50"
  } 
},
1
3
12/7/2016 2:55:28 PM

Accepted Answer

Well... I didn't get the answer I would like to have. So I did a workaround and I had to change some code in the DAL project. Hopefully it didn't break some functions for other projects...

In DAL project:
Since I was working with a EF Entity with Model first, I couldn't change the model. But it created partial classes, so I did another partial class for MyEntity with a contstructor that takes a parameter.

namespace DAL.Models
{
    public partial class MyEntities
    {
        public MyEntities(string connString) : base(connString)
        {
        }
    }
}

And in the DAL repo I created a constructor with parameter (for injection from my .NET core project) and a private method.

public class UserRepository : IUserRepository
{
    private readonly string _dbContextString;

    public UserRepository(string dbContextString)
    {
        _dbContextString = dbContextString;
    }

    private MyEntities GetMyEntities()
    {
        return string.IsNullOrEmpty(_dbContextString) ? new MyEntities() : new MyEntities(_dbContextString);
    }
    ...
}

And then I did a search and replace for uses of MyEntity(), from

    using (var context = new MyEntities())
    {
        ...

to

    using (var context = GetMyEntities())
    {
        ...

In my .NET core project:
In Startup.cs I added a line in ConfigureService to inject the connectionString in my repo.

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();

    services.AddSingleton<IUserRepository>(new UserRepository(Configuration.GetConnectionString("MyEntities")));
    ...

Tada, now it works with my new .NET core project and still working with the other .NET framework projects!

3
12/9/2016 6:39:22 AM

Popular Answer

You have to inject the IConfiguration in required controller and pass it to the Dal project

 //dependency inject it in required controller or service class
    IConfiguration Config 
 //this will get your connection string 
    Config.GetSection("ConnectionStrings").GetSection("MyEntities")


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