DotNet Core - Connection String from Class Library

Question

I have my connection string to SQL stored in the Web project in appsettings.json

  "ConnectionStrings": {
    "MyDbConnectionString": "***"
  },

Then I added a DB context using Scaffold

Scaffold-DbContext -Connection "name=MyDbConnectionString" -Provider "Microsoft.EntityFrameworkCore.SqlServer"  ...  -Force

I can use the context in a controller and I have no issues getting data or writing. However, I would like all my business logic to be on a separate class library. So here is my repository from my Library:

    public class MyRepository
{

    private static MyContext CurrentContext
    {
        get { return new MyContext(); }
    }

    public static async void AddEventLog(EventLog eventLog)
    {
        using (var context = CurrentContext)
        {
            context.EventLog.Add(eventLog);
            await context.SaveChangesAsync();
        }
    }
}

But it fails when it tries to write to the DB.

System.InvalidOperationException: 'A named connection string was used, but the name 'MyDbConnectionString' was not found in the application's configuration.

Should I be adding appsettings.json to the library project (This seems redundant, and incorrect)? What am I missing? How do I reference back to the web projects appsettings.json file?

Any help would be greatly appreciated.

Here is my startup

services.AddDbContext<MyContext>(options =>options.UseSqlServer(Configuration.GetConnectionString("MyDbConnectionString")));

score 0 · Accepted Answer · 2018-11-13 13:23:25Z

0

***** HERE ARE CHANGES I HAVE MADE TO THE WORK *****

I have found the issue I believe so here we go.

Remove the following from MySsdCaseContext.

public MySsdCaseContext()
{
}

and keep this one..

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

For the purposes of fixing this comment out the following from OnConfiguring.

if (!optionsBuilder.IsConfigured)
    {
        optionsBuilder.UseSqlServer("name=MySsdCaseDb");
    }

In startup.cs add the following inside ConfigureService method.

services.AddDbContext<MySsdCaseContext>(options 
=>options.UseSqlServer(Configuration.GetConnectionString("MySsdCaseDb")));

This should prompt you to add a reference to MySsdCase.Core.Data class library. You don't currently have this. Basically put the following at the top of startup.cs

    using MySsdCase.Core.Data;

Ensure the following is inside MySsdCase.Web.cspoj

<ItemGroup>
   <ProjectReference Include="..\MySsdCase.Core\MySsdCase.Core.csproj" />
</ItemGroup>

Do it like this...

      public class EventLogRepository 
    {
private readonly MySsdCaseContext _context;

public async Task AddEventLogAsync(EventLog eventLog)
{

    var myVar = await _context.Set<ClientDetails>()
        .AsNoTracking()
        .Select(p => p)
        .Take(2)
        .ToListAsync();
}
}

I think overall there was no reference to the DAL from the BL in startup.cs.

edited Nov 13, 2018 at 13:23

answered Nov 8, 2018 at 13:30

user9200027

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3 Comments

Mike Over a year ago

I had AddDbContext in the startup and I did not post in my question. I edited my post and added. However, you recommended to use AddDbContextPool and I tried using that and I still get the same error. BTW.. The Connection string is working since I can use it from the controller. Error is just when I use it from the Class Library.

Mike Over a year ago

I have been struggling to figure this out for a while now... I believe I have narrowed down what I am looking for to be how do I pass the connection string thorough DI to my repository. I have tried the answer on this link: stackoverflow.com/questions/43058497/… but I am still having trouble.

Mike Over a year ago

Nevermind... In the index I was not passing the context in this call: _eventRepo = new EventLogRepository(context); @Bazza I really appreciate the help! Thanks Again!

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