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1. Top results related to define dependency injection

   • Dependency Injection circular dependency .NET Core 2.0

     Top Answer

     Answered Sep 21, 2017 · 24 votes

     Circular dependencies are usually a sign for an improper application design, which should be revised. As I already mentioned in the comments, having a database context that depends on the user manager does not seem to be a good idea. This makes me assume that your database context does too much and likely violates the single-responsibility principle.

     Just looking at the dependencies of your database context, you are already adding too much application specific state in there: You not only have a dependency on the user manager, but also on the HTTP context accessor; and you are resolving the HTTP context also immediately in the constructor (which is generally not the best idea).

     From your code excerpt it seems that you want to retrieve the current user for later use. If you want to use this for example to filter queries for the user, then you should think about whether it’s really a good idea to statically bake this into the database context instance. Consider accepting an ApplicationUser inside methods instead. That way, you get rid of all those dependencies, you make your database context better testable (since the user is no longer a state of the context), and you also make the single responsibility of the context clearer:

     public IList<Thing> GetThings (ApplicationUser user){ // just an example… return Things.Where(t => t.UserId == user.Id).ToList();}-

     Note that this is also inversion of control. Instead of having the database context actively retrieve the user it should query for (which would add another responsibility, violating the SRP), it expects to be passed the user it should query for, moving the control to the calling code.

     Now, if you query stuff for the current user very often, it might become somewhat annoying to resolve the current user in a controller and then pass it to the database context. In that case, create a service to no longer repeat yourself. That service can then depend on the database context and other things to figure out the current user.

     But just clearing up your database context from stuff it shouldn’t do is enough to fix this circular dependency.

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   • Dependency Injection - What If Dependency Lifetimes Are Shorter Than The Dependent Object?

     Top Answer

     Answered Jan 27, 2011 · 1 votes

     The Spring framework's web integration addresses this problem using proxies and aspects. Longer-scoped objects are injected with proxies to the shorter-scoped objects. Each proxy knows how to fetch the "current" version of its shorter-scoped delegate, via the HTTP session or HTTP request (for session- and request-scoped beans, respectively).

     See http://static.springsource.org/spring/docs/2.5.x/reference/beans.html#beans-factory-scopes-other-injection

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     2/5

   • Dependency Injection in Angular compared to .Net Dependency Injection

     Top Answer

     Answered Feb 16, 2021 · 4 votes

     Technically, all services in Angular are scoped. However, they can be scoped to:

     • Root - an instance of a service provided in the root (or injected in AppModule) is shared between all modules and components. This is also what we call a singleton, scoped to root (entire app).

     @Injectable({ providedIn: 'root',})

     • Module - an instance of a service provided in a lazy-loaded module is shared between the components of the module. This is also a singleton, but scoped to a module.

     @NgModule({ ... providers: [{ provide: LocationStrategy, useClass: HashLocationStrategy }]})

     • Component - an instance of a service injected into a component only lives while that component lives. Once that component is destroyed, the instance o the service is also destroyed. Multiple instances of the same component each have their own instance of the service.

     @Component({ ... providers: [{ provide: ItemService, useValue: { name: 'lamp' } }]})

     This section of the documentation touches upon the hierarchy of injection: https://angular.io/guide/hierarchical-dependency-injection

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     3/5

   • Dependency Injection to resolve dependency with runtime data

     Top Answer

     Answered Aug 19, 2020 · 6 votes

     Your current approach has several downsides:

     • You inject runtime data into the constructor of your component, which can lead to complications.
     • You make use of an Abstract Factory, which is often not the best abstraction.
     • Your constructor invokes validation, while it should do nothing other than storing its incoming dependencies. This way you can compose your object graphs with confidence.

     Concerning the factory: Inject an IRepository rather than an IRepositoryFactory. This might require you to hide the real repository behind a proxy, as explained here.

     Concerning the Auth value, it depends on the need, but if the Auth value is an important part of the API of CustomerService, this justifies adding Auth as argument on the methods of CustomerService. If it is an implementation detail, inject an IAuthProvider abstraction of some sort that allows you to retrieve the value at runtime (after the object graph is built). Again, this all is described in this article.

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   • Dependency injection of type having nested dependency

     Top Answer

     Answered Jul 27, 2018 · 2 votes

     Associate the IdbContext interface with the dbContext implementation.

     Assuming

     public class dbContext: DbContext, IdbContext { //...}-

     It is failing because it was not registered and the provider does not know what to initialized when injecting IdbContext into the repository.

     services.AddDbContext<IdbContext, dbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("dbContext")));services.AddTransient<IRepository, Repository>();-

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     5/5

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2. en.wikipedia.org › wiki › Dependency_injectionDependency injection - Wikipedia

   en.wikipedia.org › wiki › Dependency_injection

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   In software engineering, dependency injection is a programming technique in which an object or function receives other objects or functions that it requires, as opposed to creating them internally. Dependency injection aims to separate the concerns of constructing objects and using them, leading to loosely coupled programs.

3. stackoverflow.com › questions › 130794design patterns - What is dependency injection? - Stack Overflow

   stackoverflow.com › questions › 130794

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   Sep 25, 2008 · Dependency injection is a pattern used to create instances of objects that other objects rely upon without knowing at compile time which class will be used to provide that functionality or simply the way of injecting properties to an object is called dependency injection.

   Code sample

   private Wheel wh= [Inject an Instance of Wheel at runtime]

   private Battery bt= [Inject an Instance of Battery at runtime]

   Car(Wheel wh,Battery bt) {

     this.wh = wh;

     this.bt = bt;...

   See more on stackoverflow

4. People also ask

   What is the difference between dependency injection and dependency injection?

   • Generally for silly, simple stuff I might pass in the dependency but it is so easy to use the DI container in most frameworks often just as easy to do that too. Dependency Injection is passing dependency to other objects or framework ( dependency injector). Dependency injection makes testing easier.

   design patterns - What is dependency injection? - Stack Overflow

   stackoverflow.com/questions/130794/what-is-dependency-injection

   See all results for this question

   What is a dependency injection technique?

   • The goal of the dependency injection technique is to remove this dependency by separating the usage from the creation of the object. This reduces the amount of required boilerplate code and improves flexibility. But before we take a look at an example, I want to tell you more about the dependency injection technique.

   Design Patterns Explained – Dependency Injection- Stackify

   stackify.com/dependency-injection/

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   What is Dependency Injection (DI)?

   • DI is a way to decouple object creation from object use. Yes, the distinction is clearly stated in my paragraph 2, "DI one of the possible implementations of DIP", in Uncle Bob's SOLID paradigm. I've also made this clear in an earlier post. The whole point of Dependency Injection (DI) is to keep application source code clean and stable:

   design patterns - What is dependency injection? - Stack Overflow

   stackoverflow.com/questions/130794/what-is-dependency-injection

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5. www.freecodecamp.org › news › a-quick-intro-toA quick intro to Dependency Injection: what it is, and when ...

   www.freecodecamp.org › news › a-quick-intro-to

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   Oct 18, 2018 · Introduction. In software engineering, dependency injection is a technique whereby one object (or static method) supplies the dependencies of another object. A dependency is an object that can be used (a service ). That’s the Wikipedia definition but still, but it’s not particularly easy to understand. So let’s understand it better.

6. www.tutorialsteacher.com › ioc › dependency-injectionDependency Injection - TutorialsTeacher.com

   www.tutorialsteacher.com › ioc › dependency-injection

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   Dependency Injection (DI) is a design pattern used to implement IoC. It allows the creation of dependent objects outside of a class and provides those objects to a class through different ways. Using DI, we move the creation and binding of the dependent objects outside of the class that depends on them. The Dependency Injection pattern involves ...

7. builtin.com › articles › dependency-injectionDependency Injection: A Guide With Examples | Built In

   builtin.com › articles › dependency-injection

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   Jan 12, 2024 · Dependency injection is a technique that involves making the interactions between objects as thin as possible through specific dependencies. This allows for loosely coupled code, or code that only depends on the required portion of a separate class to run. This reduces hard-coded dependencies and allows for cleaner, more flexible code.

8. www.geeksforgeeks.org › dependency-injectiondiDependency Injection(DI) Design Pattern - GeeksforGeeks

   www.geeksforgeeks.org › dependency-injectiondi

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   Jan 12, 2024 · In software design, dependency injection (DI) is a design pattern that aims to decouple objects from their dependencies. Instead of creating their own dependencies internally, objects receive them from an external source. Here’s an explanation of dependency injection with a practical example: Imagine a coffee shop:

9. stackify.com › dependency-injectionDesign Patterns Explained – Dependency Injection- Stackify

   stackify.com › dependency-injection

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   Mar 15, 2024 · Dependency injection is a programming technique that makes a class independent of its dependencies. It achieves that by decoupling the usage of an object from its creation. This helps you to follow SOLID’s dependency inversion and single responsibility principles.