Design: Addition information on certificate QR scan

Introduction

Currently, upon scanning the QR code on the certificate only the user name, course completed by the users plus the completion date is shown to the user. This needs to be enhanced to show the users' profile information so that it can help administrators uniquely identify and validate user credentials.

The design approach, focuses on below points.

Enable or disable of additional fields
Easy addition or deletion of additional fields for new certificates
Backward compatibility of existing certificates
Handling PII information.

Problem Statement

Add below additional fields to certificate json and make it available on QR scan.

User info:

users' state name
users' district name
users' block name
users' cluster name
users' school name

Enrolment and Assess meta data:

Course name
Course completion date
Users' assessment score (best attempt score) for all course assessments in the course

Assumptions

For all additional fields, values at the time of certificate generation are to be considered.
As QR scan is public all PII related info are masked.
The additional fields are available upon QR scan only for new certificates or re-Issued certificates.

Design

To enable addition fields in certificates, specify additionalProps as a new field in certificate template as below

{
  "additionalProps" : { <Map<String, List<String>>> // Optional, On empty, the  property is ignored
		"location": [], <List<String> like "state" "district", "block", "cluster", "school" // Optional. Details are from userLocations in user read API
		"user": [] <List<String> like "phone" // Optional. Details are from user read API
		"enrolment": [], <List<String> like "completedOn" // Optional. Details are from user_enrolments table
		"assessment": [] <List<String>> like "score" // Optional. Details are from user_activity_agg table
		"course": [] <List<String>> like "name" // Optional. Details are from content read API
	}
}

Based on the fields specified for user and enrolments the values at the time of generation of certificate are fetched
This allows addition or deletion of fields with just an update to certificate template.
Upon certificate generation, the specified additional fields are made available in related column of cert_registry as below

Below is the schema in related Coulmn with additional fields
{
  "location": { // Optional
    "state": <String>, //Optional
    "district": <String>, //Optional
    "block": <String>, //Optional
    "cluster": <String>, //Optional
    "school": <String>, //Optional
  },
  "user" :{ //Optional
    "phone": <String>, //masked phone
  }
  "enrolment": { // Optional
    "completedOn": <TimeStamp>, //Optional
  },
  "assessment": { // Optional
    "score": <Map<String, double>> //Optional
  },
  "course": { // Optional
    "name": <String>, //Optional
  }
}

Flink Job changes

In certificate-pre-processor flink job, add a new configuration as below.

pii_fields = ["userName"]

If additionalProps present in certificate template then,
- Fetch user details from user read API response
- Fetch masked values for PII fields
- Fetch enrolment related data from user_enrolments
- Fetch score data from user_activity_agg table aggregates column.
Prepare the related column data and insert into cert-registry

Conclusion:

<TODO>