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:
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}
​
@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}`);}
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
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}`);}