Error when trying to inject a service into an angular component “EXCEPTION: Can’t resolve all parameters for component”, why?

Import it from the file where it is declared directly instead of the barrel. I don’t know what exactly causes the issue but I saw it mentioned several times (probably some kind of circular dependency). It should also be fixable by changing the order of the exports in the barrel (don’t know details, but was … Read more

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘demoRestController’

Your DemoApplication class is in the com.ag.digital.demo.boot package and your LoginBean class is in the com.ag.digital.demo.bean package. By default components (classes annotated with @Component) are found if they are in the same package or a sub-package of your main application class DemoApplication. This means that LoginBean isn’t being found so dependency injection fails. There are a couple of ways to solve your problem: Move LoginBean into com.ag.digital.demo.boot or a sub-package. Configure … Read more

Why is IoC / DI not common in Python?

I don’t actually think that DI/IoC are that uncommon in Python. What is uncommon, however, are DI/IoC frameworks/containers. Think about it: what does a DI container do? It allows you to wire together independent components into a complete application … … at runtime. We have names for “wiring together” and “at runtime”: scripting dynamic So, a DI container is nothing … Read more

Why is IoC / DI not common in Python?

I don’t actually think that DI/IoC are that uncommon in Python. What is uncommon, however, are DI/IoC frameworks/containers. Think about it: what does a DI container do? It allows you to wire together independent components into a complete application … … at runtime. We have names for “wiring together” and “at runtime”: scripting dynamic So, a DI container is nothing … Read more

Unable to resolve service for type while attempting to activate

For the Dependency Injection framework to resolve IRepository, it must first be registered with the container. For example, in ConfigureServices, add the following: AddScoped is just one example of a service lifetime: For web applications, a scoped lifetime indicates that services are created once per client request (connection). See the docs for more information on Dependency Injection in ASP.NET Core.

ASP.NET Core Dependency Injection error: Unable to resolve service for type while attempting to activate

To break down the error message: Unable to resolve service for type ‘WebApplication1.Data.BloggerRepository’ while attempting to activate ‘WebApplication1.Controllers.BlogController’. That is saying that your application is trying to create an instance of BlogController but it doesn’t know how to create an instance of BloggerRepository to pass into the constructor. Now look at your startup: That is saying whenever a IBloggerRepository is required, create a BloggerRepository and … Read more

What is a JavaBean exactly?

A JavaBean is just a standard All properties are private (use getters/setters) A public no-argument constructor Implements Serializable. That’s it. It’s just a convention. Lots of libraries depend on it though. With respect to Serializable, from the API documentation: Serializability of a class is enabled by the class implementing the java.io.Serializable interface. Classes that do not implement this interface will not … Read more