Policies (Filters)

Guard your methods
Policies gives you the ability to apply arguments check on a function with zero effort.
SugoiJS provides policy which can be use for guarding any method.
The Policies are used by two simple steps:
Decorate your verification method with - @Policy(policyId?:string)
This decorator registers the function as "policy validator", this will later be used as guardian middleware.
policyId?: string - This ID will be used as an alias for calling this function, default is ${class name}.${function name}
Example
​
 @Policy() //register this function as policy using the class name and function name, same as use @Policy("myNumberValidation")
    static myNumberValidation(
    policyData:{functionArgs: any[], 
    policyMeta: Array<{argIndexToValidate:number,maxValue:number}>
    }): true|any{
​
        // Those are the meta data values 
        // which passed into the decorator itself while using @UsePolicy()
        const argIndexToValidate = policyMeta[0].argIndexToValidate;
        const maxValue = policyMeta[0].maxValue;
​
        if(policyData.functionArgs[argIndexToValidate] < maxValue){
            return true; //Is valid, continue to the function/next policy or middleware
        }else{
            return policyData.functionArgs[argToValidate]; // so we will be able to identify the issue on the exception
        }
    }
2. @UsePolicy(policy: TPolicy|string, failedResponseCode: number = 400, ...policyMeta: any[])
This decorator sets a policy guard on the function it decorates:
policy:TPolicy| string - For setting the referenced policy, use the policy ID from the previous section or anonymous function reference.
failedResponseCode: number - The code will be stored under the exception if the value does not meet the criteria.
policyMeta: any[] - Any further payload data which should pass to the policy.
​
/**
* Apply policy by anonymous function
* only numbers lower than 5 will log
**/
@UsePolicy((myNumber: number)=> myNumber < 5)
lowerThan5NumberLogger(myNumber){
    console.log(`number is lower the 5! ${myNumber}`);
}
Build your own policies:
Policy can be any function of type TPolicy
TPolicy = (policyData?:{functionArgs: any[], policyMeta: any[]})=>(Promise < (true|any) > | (true|any))
When the result is boolean, true means that the data is valid, all other values will be shown on the exception
Policy full example:
class Validators{
​
    @Policy() //register this function as policy using the class name and function name, same as use @Policy("Validators.myNumberValidation")
    static myNumberValidation(policyData:{functionArgs: any[], policyMeta: {argIndexToValidate:number,maxValue:number}[]}): true|any{
        const myMeta = policyMeta[0];
        //those are the meta data values which passed to the decorator itself while using @UsePolicy()
        const argIndexToValidate = myMeta.argIndexToValidate;
        const maxValue = myMeta.maxValue;
​
        if(policyData.functionArgs[argIndexToValidate] < maxValue){
            return true; //Is valid, continue to the function/next policy
        }else{
            return policyData.functionArgs[argToValidate]; //so we will be able to identify the issue on the exception
        }
    }
}
​
@UsePolicy("Validators.myNumberValidation",{argIndexToValidate:0,maxValue:5})
lowerThan5NumberLogger(myNumber){
    console.log(`number is lower the 5! ${myNumber}`);
}

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Pre-defined polices

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Guard your methods

Decorate your verification method with - @Policy(policyId?:string)