Where and how should the database connection statement be stored?

Hi,@fatih uyanık. Welcome to Microsoft Q&A .
In a WPF project with Entity Framework (EF), storing database connection information in the configuration is a good practice. You could refer to the following approaches.

In .NET Framework:

Store the connection string in the application configuration file (App.config for WPF ). This allows you to change the connection string without modifying the code. The configuration file might look like this:

<configuration>
  <connectionStrings>
    <add name="YourDbContextName" connectionString="YourConnectionStringHere" providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

Retrieve the connection string in your DbContext configuration using ConfigurationManager.ConnectionStrings["YourDbContextName"].ConnectionString.

public class YourDbContext : DbContext
{
    public YourDbContext() : base(GetDbContextOptions())
    {
    }

    private static DbContextOptions<YourDbContext> GetDbContextOptions()
    {
        var connectionString = ConfigurationManager.ConnectionStrings["YourDbContext"].ConnectionString;

        var optionsBuilder = new DbContextOptionsBuilder<YourDbContext>();
        optionsBuilder.UseSqlServer(connectionString); // Or UseSqlite, UseMySQL, etc., depending on your database provider

        return optionsBuilder.Options;
    }
}

In .NET 6 (.NET Core): In a .NET WPF project, you could leverage the appsettings.json file or other configuration sources.

Create AppSettings.json File:

• Right-click on your WPF project in Visual Studio.
• Add a new item and choose "JSON File" or "Text File" and rename it to appsettings.json.

Configure the AppSettings.json File:

• Open the appsettings.json file and define your configuration settings.

{
  "ConnectionStrings": {
    "YourDatabaseConnection": "your_actual_connection_string"
  }
}

Load Configuration in Code:

In your WPF application, you need to load the configuration during application startup. Note that you'll need to install the Microsoft.Extensions.Configuration NuGet package if you haven't already. Example:

   using Microsoft.Extensions.Configuration;
   
   public partial class App : Application
   {
       protected override void OnStartup(StartupEventArgs e)
       {
           var configuration = new ConfigurationBuilder()
               .SetBasePath(Directory.GetCurrentDirectory())
               .AddJsonFile("appsettings.json")
               .Build();
   
           // Access configuration settings here if needed...
   
           base.OnStartup(e);
       }
   }
   

Inject Configuration to DbContext or Services:

Pass the configuration to your DbContext or services during their instantiation. You can set the connection string from the configuration.

services.AddDbContext<YourDbContext>(options =>
    options.UseSqlite(configuration.GetConnectionString("YourDatabaseConnection")));

Use Dependency Injection:

Leverage dependency injection to inject the DbContext into your services or wherever you need it.

public class YourService
{
    private readonly YourDbContext _dbContext;

    public YourService(YourDbContext dbContext)
    {
        _dbContext = dbContext;
    }
}

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.