Resolution Context

The function of a Container is to store the registrations you perform, and the ResolutionContext is the entry point to encapsulate all the resolution of the values you want. The returned values, which have Scope.CONTEXT scope, will be cached in the resolution context. This means that the context will return the same instance each time a resolution for this dependency is requested.

Contexts can be useful if you need more control over when new instances are created. A practical example of this is when we need to get a new instance on every HTTP request and we want this instance to be reused within that request.

Creating a Resolution Context

You can also get a resolution context from a container and use it to resolve the dependencies you need.

import { Microinjection } from "@microkits/microinjection";

const container = Microinjection.getDefaultContainer();
const context = container.createResolutionContext();

A context is able to access the registrations of the container responsible for its creation and its ancestors.

note

When you use container.resolve(), you are actually asking the container to create a ResolutionContext and ask it to resolve the dependency for you.

Context Hierarchy

As with containers, you can also have a hierarchy of resolution contexts. When we ask the context to resolve a context scoped instance, it will first look for an instance in its cache, then look in its ancestors cache, and then try to create a new instance using existing registrations in the container.

import { Microinjection } from "@microkits/microinjection";

const container = Microinjection.getDefaultContainer();

class User {}

container.register("user").asClass(User).inContextScope();

const parentContext = container.createResolutionContext();
const childContext = parentContext.createChildContext();

const user1 = parentContext.resolve("user");
const user2 = childContext.resolve("user");

// user1 and user2 are the same instance
console.log(user1 === user2); // true