ASP.NET core - Configuration file not being mapped to POCO

Question

I have read plenty of similar-ish questions, yet nothing worked for me. I am most likely doing something wrong but I don't see what.

Below is the config file I created, called ErrorCodes.json at the root of the project (same level as appsettings.json ):

{
  "ErrorMap": {
    "Type": {
      "Input": {
        "Null": {
          "Code": "ABC-1000",
          "Message": "The request body is null or empty"
        },
        "Name": {
          "Code": "ABC-1001",
          "Message": "The 'name' property was not set"
        },
        "Age": {
          "Code": "ABC-1002",
          "Message": "The 'age' property was not set"
        },
        "Email": {
          "Code": "ABC-1003",
          "Message": "The 'email' property was not set"
        }
      }
    }
  }
}

In startup.cs I have the following constructor:

public Startup()
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("ErrorCodes.json", optional: false, reloadOnChange: false)
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: false);

    this.configuration = builder.Build();
}

And my ConfigureServices method is here:

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<ErrorMap>(configuration.GetSection(nameof(ErrorMap)));
    services.AddSingleton(
        context => context.GetRequiredService<IOptions<ErrorMap>>().Value);
    )
    services.AddSingleton<ErrorCodeConfig>();
    // some other stuff
}

ErrorCodeConfig is a "bean" (not sure about the name for that in the C# world) that depends on ErrorMap , it's defined as such:

public class ErrorCodeConfig
{
    private readonly ErrorMap _errors;

    public ErrorCodeConfig(ErrorMap errors)
    {
        _errors = errors;
    }

    public Error Get(string typeKey, string errorKey)
    {
        return _errors.Get(typeKey, errorKey);
    }
}

The class ErrorMap and Error are defined as such:

public class ErrorMap
{
    public Dictionary<string, Dictionary<string, Error>> Type;

    public Error Get(string key, string key2)
    {
        return Type.GetValueOrDefault(key).GetValueOrDefault(key2);
    }
}

public class Error
{
    public string Code { get; set; }
    public string Message { get; set; }
}

I can run the application, everything gets injected properly except the Dictionary in the ErrorMap class. It remains null and I am not sure why.

Here is what I have tried so far:

• I used a wrong name in the ConfigurationBuilder to see if it was a read problem, so I temporarily renamed my file, and as it could not find it it threw an exception. So I'm assuming that at the very least it can find the file.
• I appended appsettings.json with my ErrorMap block to see if I could have it injected with the default config file, but I got no luck. It didn't crash but the config class was still not populated.

Would you have any ideas of what I did wrong in my project? Thanks for reading

Answer 1

Tested on my computer with

var errorMap = new ErrorMap();
Configuration.GetSection(nameof(ErrorMap)).Bind(errorMap);

with this version of ErrorMap

public class ErrorMap
{
    public Dictionary<string, Dictionary<string, Error>> Type { get; set; }

    public Error Get(string key, string key2)
    {
        return Type.GetValueOrDefault(key).GetValueOrDefault(key2);
    }
}