How to read a connectionString WITH PROVIDER in .NET Core?

Question

I added

.AddJsonFile(\"Connections.json\", optional: true, reloadOnChange: true)

in

 public Startup(IHostingEnvironment e         


        

Answer 1

An old question, but I was looking at this issue today and thought I'd share ...

A Simple Alternative to Including ProviderName

Here is a simple alternative that avoids custom extensions and altering the default ConnectionStrings configuration structure. It's based on how Microsoft includes a ProviderName for apps on Azure.

The solution is to add a context related key in the ConnectionStrings section that specifies the ProviderName.

AppSettings.json with SQLite provider:

{  
  "ConnectionStrings": {
    "MyContext": "Data Source=c:\\MySqlite.db;Version=3;",
    "MyContext_ProviderName": "System.Data.SQLite",
  }
}

And in the C# code read the values with the GetConnectionString() method:

var connectionString = Configuration.GetConnectionString("MyContext");
var providerName = Configuration.GetConnectionString("MyContext_ProviderName") ?? "";

if (Regex.IsMatch(providerName, "SQLite", RegexOptions.IgnoreCase)) 
{
    builder.UseSqlite(connectionString);
}
else if (Regex.IsMatch(providerName, "Oracle", RegexOptions.IgnoreCase)) 
{    
    builder.AddOracle(connectionString);
}
else if (... 

Bonus - Connection String Prefixes

Microsoft includes predefined prefixes for SQLClient and MySQL which will automatically include the provider name in the above format. However, these prefixes only work when added as environment variables, i.e., not in appsettings.json. For example, defining the connection string in launchSettings.json with the MYSQLCONNSTR_ prefix would populate both the connection string and provider name. For detains, see Configuration in ASP.NET Core and scroll down to Connection string prefixes

launchSettings.json

{
  "profiles": {
    "Development": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "",
      "environmentVariables": {
       "ASPNETCORE_ENVIRONMENT": "Development",

       // The prefix
       "MYSQLCONNSTR_MyContext": "Server=myServerAddress;Database=Green;Uid=myUsername;Pwd=myPassword;"

      }
    }
}