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c#dependency-injectionblazor.net-5
Nick Gelotte
Nick Gelotte

Reputation: 377

Mixing Blazor Components, DI and C# 8 nullable

I am using .net 5 for a Blazor app in a project with nullable enabled. It is using Code Behind to create Blazor Components. I want to use a constructor so that I can avoid marking every non DI property as nullable to simplify accessing them in my blazor code. However, If I create a constructor like public PageNumberOne(ILogger<PrimaryItem> logger) {}

I get the error MissingMethodException: No parameterless constructor defined for type

If I use the inject attribute on the DI items then I have the warning - Non-nullable property _logger must contain a non-null value when exciting the constructor

So how do I mix DI with nullable without just marking every property as nullable?

I could also create them in the main body of the "code" block but then I cannot access my DI items for initialization because they are not available until the OnInitialized. So again I have to mark them as Nullable.

Upvotes: 16

Views: 4008

Answers (1)

dani herrera
dani herrera

Reputation: 51755

Microsoft advice from Request a service in a component at ASP.NET Core Blazor dependency injection documentation:

Since injected services are expected to be available, don't mark injected services as nullable. Instead, assign a default literal with the null-forgiving operator (default!).

[Inject]
private IExampleService ExampleService { get; set; } = default!;

Upvotes: 25

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