Local Interceptor

Create Interceptor

For example, we create a Local Interceptor logger in the module demo-student

1. Cli command

$ vona :create:bean interceptor logger --module=demo-student

2. Menu command

TIP

Context Menu - [Module Path]: Vona Aspect/Interceptor

Interceptor Definition

export interface IInterceptorOptionsLogger extends IDecoratorInterceptorOptions {}

@Interceptor<IInterceptorOptionsLogger>()
class InterceptorLogger {
  async execute(_options: IInterceptorOptionsLogger, next: Next) {
    const timeBegin = Date.now();
    const res = await next();
    const timeEnd = Date.now();
    console.log('time: ', timeEnd - timeBegin);
    return res;
  }
}

• IInterceptorOptionsLogger: Defines interceptor parameters
• execute: Outputs execution time

Using Interceptor

1. Annotating controller actions

import { Aspect } from 'vona-module-a-aspect';

@Controller()
class ControllerStudent {
  @Web.get()
+ @Aspect.interceptor('demo-student:logger')
  async findMany() {}
}

• @Aspect.interceptor: This decorator is used to use local interceptor. Simply pass the interceptor name
  • The logger interceptor belongs to the demo-student module, so the full name is demo-student:logger

2. Annotating controller class

You can use interceptor for controller classes so that all actions in the class will apply this interceptor

import { Aspect } from 'vona-module-a-aspect';

@Controller()
+ @Aspect.interceptor('demo-student:logger')
class ControllerStudent {
  @Web.get()
  async findMany() {}
}

Interceptor Parameters

You can define parameters for interceptor, allowing for more flexible configuration of interceptor logic

For example, define the prefix parameter for the logger interceptor to control the output format

1. Defining parameter types

export interface IInterceptorOptionsLogger extends IDecoratorInterceptorOptions {
+ prefix: string;
}

2. Providing default values ​​for parameters

@Interceptor<IInterceptorOptionsLogger>({
+ prefix: 'time',
})

3. Using Parameters

export interface IInterceptorOptionsLogger extends IDecoratorInterceptorOptions {
  prefix: string;
}

@Interceptor<IInterceptorOptionsLogger>({
  prefix: 'time',
})
class InterceptorLogger {
  async execute(options: IInterceptorOptionsLogger, next: Next) {
    const timeBegin = Date.now();
    const res = await next();
    const timeEnd = Date.now();
-   console.log('time: ', timeEnd - timeBegin);
+   console.log(`${options.prefix}: `, timeEnd - timeBegin);
    return res;
  }
}

4. Specify parameters when using

You can specify local interceptor parameters for a specific API

class ControllerStudent {
  @Web.get()
+ @Aspect.interceptor('demo-student:logger', { prefix: 'elapsed' })
  async findMany() {}
}

• When using interceptor, just provide the parameter value directly

5. App config

Interceptor parameters can be configured in App config

src/backend/config/config/config.ts

// onions
config.onions = {
  interceptor: {
    'demo-student:logger': {
      prefix: 'elapsed',
    },
  },
};

6. Parameter precedence

Specify parameters when using > App config > Default values