Reading connection string in class library dotnet core

Hi,

I have a solution in which there are 2 projects

1. DotNet Core API 2.2

2. DotNet Core Class library

There is a connection string defined in appsettings json file in api project. I want to read that connection string in class library project via dependency injection and return connection object.

I have tried different approaches to resolve but nothing seems to be working for me.

Can anyone explain or suggest a detailed example which can be reference point to implement the same.

Thanks in advance.

Thanks

Dheeraj

In your class library project, you need to create a DB context class. Right-click and add new class in you're class library project and inherit BaseContext. Like below

public class MyDBContext : BaseContext, IMyDBContext
{
public MyDBContext(IConfiguration configuration, IConnectionStringProvider connectionStringProvider)
: base(configuration, connectionStringProvider, "ConnectionStringInAppSettingsKeyNameHere")
{
}
}

public interface IMyDBContext : IBaseContext
{
}

Create DB Context factory like below

public class DbContextFactory : IDesignTimeDbContextFactory
{
public MyDBContext CreateDbContext(string[] args)
{
IConfigurationRoot configuration = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("appsettings.json")
.Build();
return new MyDBContext(configuration,null);
}
}

That's it. You can use this context to do all DB operations in you're class library project.
Usage Example:

public class MyAnOtherClass
{
private readonly IMyDBContext context;
public MyAnOtherClass(IMyDBContext context)
{
this.context = context;
}
public PerformAnyDBOperstion(){
var con = context.DbContext.Database.GetDbConnection();
}
}

You need to add this in your main project, startup.cs

services.AddScoped();

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Veerendra Annigere6y ago
In your class library project, you need to create a DB context class. Right-click and add new class in you're class library project and inherit BaseContext. Like below
public class MyDBContext : BaseContext, IMyDBContext
    {
        public MyDBContext(IConfiguration configuration, IConnectionStringProvider connectionStringProvider)
            : base(configuration, connectionStringProvider, "ConnectionStringInAppSettingsKeyNameHere")
        {
        }
}
public interface IMyDBContext : IBaseContext
    {
    }
Create DB Context factory like below
public class DbContextFactory : IDesignTimeDbContextFactory
   {
       public MyDBContext CreateDbContext(string[] args)
       {
           IConfigurationRoot configuration = new ConfigurationBuilder()
               .SetBasePath(Directory.GetCurrentDirectory())
               .AddJsonFile("appsettings.json")
               .Build();

           return new MyDBContext(configuration,null);
       }
   }
That's it. You can use this context to do all DB operations in you're class library project.
Usage Example:
    public class MyAnOtherClass
    {
       private readonly IMyDBContext context;

        public MyAnOtherClass(IMyDBContext context)
        {
            this.context = context;
        }

       public PerformAnyDBOperstion(){
          var con = context.DbContext.Database.GetDbConnection();
       }
}
You need to add this in your main project, startup.cs
services.AddScoped();