Dependency Injection in ASP.NET Core and issue with null suppresion

Hi, I'm having some issues with null suppression and dependency injection in ASP.NET Core

I have this block of code

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

And it wasn't able to resolve

Cannot resolve scoped service 'RemoteGatewayManager.Types.Classes.AppDb' from root provider

Cannot resolve scoped service 'RemoteGatewayManager.Types.Classes.AppDb' from root provider

I also tried with DbContext

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

And the

provider.GetService<AppDb>()!

provider.GetService<AppDb>()!

returns

null

null

, but doesn't throw. Isn't it supposed to throw for being null?
Also why is it returning null instead of telling that it is not able to resolve service?

Edit:

AppDb

AppDb

is a class that inherrits from

DbContext

DbContext

Thanks in advance

C#•4y ago•

12 replies

kunio_kun

Dependency Injection in ASP.NET Core and issue with null suppresion

Hi, I'm having some issues with null suppression and dependency injection in ASP.NET Core

I have this block of code

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

And it wasn't able to resolve

Cannot resolve scoped service 'RemoteGatewayManager.Types.Classes.AppDb' from root provider

Cannot resolve scoped service 'RemoteGatewayManager.Types.Classes.AppDb' from root provider

I also tried with DbContext

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

builder.Services.AddDbContext<AppDb>();
builder.Services.AddHostedService(provider =>
    new DbMigrator(provider.GetService<ILogger<DbMigrator>>()!, provider.GetService<AppDb>()!)
);

And the

provider.GetService<AppDb>()!

provider.GetService<AppDb>()!

returns

null

null

, but doesn't throw. Isn't it supposed to throw for being null?
Also why is it returning null instead of telling that it is not able to resolve service?

Edit:

AppDb

AppDb

is a class that inherrits from

DbContext

DbContext

Thanks in advance

Dependency Injection in ASP.NET Core and issue with null suppresion

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