Guards

Guards implemented on top of pipelines have a single responsibility to check if a method can be activated. guard pipeline must implement the IGuard interface.

if the guard decorate a class it will run on all class methods.

Usage#

import {guard,IGuard} from '@appolo/engine';
import {define} from '@appolo/inject';

@define()
export class AuthGuard implements IGuard{

   async isValid(context:PipelineContext){
      
        return context.value > context.metadata.max;
   }
}

export const authGuard = (max:number)=> guard(AuthGuard,{max})

now lets use out authGuard

@define()
export class SomeClass {
    
    @authGuard(5)
    test(value:number){
        return value*value;
    }
}

injector.get<SomeClass>(SomeClass).test(4) 

injector.get<SomeClass>(SomeClass).test(6)  // throw GuardError

Custom Error#

you can also throw your own custom error

import {guard,IGuard} from '@appolo/engine';
import {define} from '@appolo/inject';

@define()
export class AuthGuard implements IPipeline{
    
    async isValid(context:PipelineContext):Promise<boolean>{
      
        if(context.value > context.metadata.max){
            return true;  
        }
        throw new MyCustomError()

   }
}

Roles Guard example#

we assume we a user context on our request

import {IGuard,guard,setMetadata,Discovery} from '@appolo/engine';
import {define} from '@appolo/inject';


@define()
export class RolesGuard implements IGuard{

    @inject() discovery:Discovery;

   async isValid(context:PipelineContext){

        let roles  = this.discovery.getReflectMetadata<string[]>("roles",context.type,context.action)
        
        if(!roles){
            return true;
        }   

        let req = context.value,user = req.user;
        
        if(roles.some(role=> user.indexOf(role)>-1)){
            return true
        }
        throw new UnauthorizedError();       
   }
}

export const rolesGuard =  guard(RolesGuard)
export const  roles = (roles:string[])=>setMetadata("roles",roles);

now we check the controller

 
@controller()
@rolesGuard()
export class SomeController extends Controller{
   
    @get("/some/data")
    @roles("admin")
    public async getData(@req req:IRequest){
        return this.send(this.getModel())
    }
}