c# - Console App - A named connection string was used, but the name 'DefaultConnection' was not found in the app

I have an issue where I am getting the following error when running my console app.

A named connection string was used, but the name 'DefaultConnection' was not found in the application's configuration

This is my program.cs

static async Task Main(string[] args)
{
    var configuration = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .Build();

    var sss = configuration.GetConnectionString("DefaultConnection");
    Console.WriteLine(sss);
    var serviceProvider = new ServiceCollection()
        .AddLogging(configure => configure.AddSerilog())
        .AddDbContext<MydbContext>(options => options.UseSqlServer(configuration.GetConnectionString("DefaultConnection")), ServiceLifetime.Transient)
        .AddScoped<IDataService, DataService>()
        .AddScoped<IMemoryCache, MemoryCache>()
        .AddScoped<IStockDataImportService, StockDataImportService>()
        .BuildServiceProvider();

    IStockDataImportService importService = serviceProvider.GetRequiredService<IStockDataImportService>();


    Console.WriteLine("Stock Data Import process started!");
    await FetchFile(logger, importService, configuration);
}

Now if I look at var sss. It contains the correct connection string so I know it is loading it from config correctly.

However I think it may be something to do with the GetRequiredService() line...

Either way my DataService class does not get the dbcontext correctly. It is a constructor parameter in the StockDataImporter class

public StockDataImportService(IDataService serv)
{
    _serv = serv;
}

and the dataservice class

public DataService(MydbContext context, IMemoryCache memoryCache) 
{
    _context = context;
    string? ddd = _context.Database.GetConnectionString();
    _memoryCache = memoryCache;
}

What am I doing wrong?

I have an issue where I am getting the following error when running my console app.

A named connection string was used, but the name 'DefaultConnection' was not found in the application's configuration

This is my program.cs

static async Task Main(string[] args)
{
    var configuration = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .Build();

    var sss = configuration.GetConnectionString("DefaultConnection");
    Console.WriteLine(sss);
    var serviceProvider = new ServiceCollection()
        .AddLogging(configure => configure.AddSerilog())
        .AddDbContext<MydbContext>(options => options.UseSqlServer(configuration.GetConnectionString("DefaultConnection")), ServiceLifetime.Transient)
        .AddScoped<IDataService, DataService>()
        .AddScoped<IMemoryCache, MemoryCache>()
        .AddScoped<IStockDataImportService, StockDataImportService>()
        .BuildServiceProvider();

    IStockDataImportService importService = serviceProvider.GetRequiredService<IStockDataImportService>();


    Console.WriteLine("Stock Data Import process started!");
    await FetchFile(logger, importService, configuration);
}

Now if I look at var sss. It contains the correct connection string so I know it is loading it from config correctly.

However I think it may be something to do with the GetRequiredService() line...

Either way my DataService class does not get the dbcontext correctly. It is a constructor parameter in the StockDataImporter class

public StockDataImportService(IDataService serv)
{
    _serv = serv;
}

and the dataservice class

public DataService(MydbContext context, IMemoryCache memoryCache) 
{
    _context = context;
    string? ddd = _context.Database.GetConnectionString();
    _memoryCache = memoryCache;
}

What am I doing wrong?

• c#
• entity-framework
• console-application
• .net-8.0

Share Improve this question Follow asked Jan 2 at 20:00 coolblue2000coolblue2000 5,0081414 gold badges4545 silver badges7575 bronze badges 7

• yes, and the variable sss gets set with the correct value from that. So that part seems to be working fine. – coolblue2000 Commented Jan 2 at 20:14
• Can you please share full minimal reproducible example? If not can you please add MydbContext? – Guru Stron Commented Jan 2 at 20:15
• This is in a larger solution and the dbcontext is shared with a blazor app that works fine. so the dbcontext works. The appsettings work, it appears more to do with the dependency injection going wrong somewhere. – coolblue2000 Commented Jan 2 at 20:19
• 1 I highly suspect that if I run the provided code it will work just fine for me. There is nothing wrong with the DI in the provided code at the first glance. Please try sharing as much info as possible otherwise it would be hard to help you. Also can you please add a full error text (currently it seems to have nothing to do with the DI). – Guru Stron Commented Jan 2 at 20:23
• Okay, if I remove the following line from the dbcontext it works... protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) => optionsBuilder.UseSqlServer("name=DefaultConnection"); I have no idea why this works fine in the blazor project but not in the console app. – coolblue2000 Commented Jan 2 at 20:24

 |  Show 2 more comments

1 Answer 1

Sorted by: Reset to default 1

To fix your problem either remove the OnConfiguring(DbContextOptionsBuilder optionsBuilder) override or change it to something like:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    if (!optionsBuilder.IsConfigured)
    {
        optionsBuilder.UseSqlServer("name=DefaultConnection");
    }
}

so why is it the case that it works in blazor with the onconfigure but not the console app?

I would guess that it works because it seems that you have IConfiguration registered in your Blazor app DI container. If you take a look at the code for NamedConnectionStringResolverBase which as far as I can see is internally invoked when processing the connection string then you will see that it will try to resolve and use the IConfiguration:

// HERE:
var configuration = ApplicationServiceProvider
    ?.GetService<IConfiguration>();

var resolved = configuration?[connectionName]
               ?? configuration?[DefaultSection + connectionName];

if (resolved == null)
{
    throw new InvalidOperationException(
        RelationalStrings.NamedConnectionStringNotFound(connectionName));
}

Of course you can try "fixing" your console app by registering the configuration in the container but still it is not the best option compared to the one suggested.