Class PricingEvaluatorUtil

Package io.github.isagroup

public class PricingEvaluatorUtil extends Object

Utility class that provides methods to generate and manage JWT that contains the pricing plan evaluation context.

It can be used to evaluate the context of an user compared to his plan and generate a JWT with the results, using a single java method. This class consumes the information of the configured PricingContext to perform its operations.

Once a class that extends from PricingContext exists inside your Spring application, PricingEvaluatorUtil can be injected in any bean by using @Autowired. Once declared, the token can be generated using the generateUserToken method:

import io.github.isagroup.PricingEvaluatorUtil;

@Component
public class MyComponent {

    @Autowired
    private PricingEvaluatorUtil pricingEvaluatorUtil;

    public String myMethod() {
        String token = pricingEvaluatorUtil.generateUserToken();
        String newToken = pricingEvaluatorUtil.addExpressionToToken(
            firstToken,
            "feature1",
            "userContext['feature1use'] < planContext['usageLimits']['feature1']");
        return token;
    }
}

Considering one BOOLEAN and two NUMERIC features, myMethod may generate a JWT with the following payload:

{
  "features": {
    "feature1": {
      "eval": "userContext['feature1use'] < planContext['usageLimits']['feature1Limit']",
      "used": 2,
      "limit": 2
    },
    "feature2": {
      "eval": true,
      "used": 1,
      "limit": 5
    },
    "feature3": {
      "eval": false,
      "used": null,
      "limit": null
    }
  },
  "sub": "Default",
  "exp": 1746083891,
  "userContext": {
    "feature1use": 2,
    "feature2use": 1
  },
  "iat": 1745997491,
  "planContext": {
    "name": "BASIC",
    "description": null,
    "price": 0,
    "unit": "user/month",
    "isPrivate": false,
    "features": {
      "feature1": false,
      "feature2": true,
      "feature3": false
    },
    "usageLimits": {
      "feature1Limit": 2,
      "feature2Limit": 5
    }
  }
}

Method summary

Constructor details

PricingEvaluatorUtil

public PricingEvaluatorUtil(PricingContext pricingContext)

Parameters:

pricingContext - The corresponding implemented PricingContext object

Method details

generateUserToken

public String generateUserToken()

Generate a user authentication JWT that includes the pricing plan evaluation context. This token is generated by using the information provided by the configured PricingContext.

Returns: a String with the encoded JWT that contains all the information

addExpressionToToken

public String addExpressionToToken(String token, String featureId, String expression)

Modifies the given JWT by changing the evaluation of the given feature by a String expression that will be evaluated on the client side of the application.

Parameters:

token - JWT returned generated by generateUserToken method

featureId - the name or id of the feature that is defined inside the token body

expression - the expression of the feature that will replace its evaluation

Returns: a modified version of the provided JWT that contains the new expression in the eval attribute of the feature inside features claim.

Usage:

public class Example {

    private PricingEvaluatorUtil pricingEvaluatorUtil;

    public Example(PricingEvaluatorUtil pricingEvaluatorUtil) {
      this.pricingEvaluatorUtil = pricingEvaluatorUtil;
    }

    public static void main(String[] args) {
        String firstToken = pricingEvaluatorUtil.generateUserToken();
        String newToken = pricingEvaluatorUtil.addExpressionToToken(
            firstToken,
            "feature1",
            "userContext['feature1use'] < planContext['usageLimits']['feature1']");
    }
}

The new payload for the JWT token will have:

{
  "features": {
    "feature1": {
      "eval": "userContext['feature1use'] < planContext['feature1']",
      "limit": 2,
      "used": 2
    }
    // other claims...
  }
}