Basic Examples

Here are just basic examples.

Getting Instance#

Binding types and scopes are detailed in Binding Types and Binding Scopes sections of the documentation.

import { Container, token } from 'brandi';

class ApiService {}

const TOKENS = {
  /*          ↓ Creates a typed token. */
  apiService: token<ApiService>('apiService'),
};

const container = new Container();

container
  .bind(TOKENS.apiService)
  .toInstance(ApiService) /* ← Binds the token to an instance */
  .inTransientScope(); /*    ← in transient scope. */

/*                           ↓ Gets the instance from the container. */
const apiService = container.get(TOKENS.apiService);

expect(apiService).toBeInstanceOf(ApiService);

Snapshoting#

import { Container, token } from 'brandi';

const TOKENS = {
  apiKey: token<string>('API Key'),
};

const container = new Container();

container
  .bind(TOKENS.apiKey)
  .toConstant('#key9428'); /* ← Binds the token to some string. */

/*        ↓ Captures (snapshots) the current container state. */
container.capture();

container
  .bind(TOKENS.apiKey)
  .toConstant('#testKey'); /* ← Binds the same token to another value. */
                           /*   For example, this can be used in testing. */

const testKey = container.get(TOKENS.apiKey);

/*        ↓ Restores the captured container state. */
container.restore();

const originalKey = container.get(TOKENS.apiKey);

expect(testKey).toBe('#testKey');
expect(originalKey).toBe('#key9428');

Other Container methods are detailed in Container section of the documentation.

Hierarchical Containers#

Hierarchical containers are detailed in Hierarchical Containers section of the documentation.

import { Container, token } from 'brandi';

class ApiService {}

const TOKENS = {
  apiService: token<ApiService>('apiService'),
};

const parentContainer = new Container();

parentContainer
  .bind(TOKENS.apiService)
  .toInstance(ApiService)
  .inTransientScope();

/*                     ↓ Creates a container with the parent. */
const childContainer = new Container().extend(parentContainer);

/**                ↓ That container can't satisfy the getting request,
 *                   it passes it along to its parent container.
 *                   The intsance will be gotten from the parent container.
 */
const apiService = childContainer.get(TOKENS.apiService);

expect(apiService).toBeInstanceOf(ApiService);