[SalesForce] JSON String test class

Regarding the event_data issue: your JSON is inconsistent. In one case it's an object containing the user_agent string:

"event_data": {
                "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36"
            },

And elsewhere it's a list of quiz_data:

"event_data": [
                {
                    "quiz_question_id": "220",
                    "answer": null
                },
                {
                    "quiz_question_id": "221",
                    "answer": []
                } [...]
            ],

This wouldn't be picked up by a JSON linter, because it's just checking that the data is valid - not that it's consistent.

I notice that the parser code generated by JSON2Apex is different from your parser code above, and e.g. creates different classes to handle the different types of answers and event_data:

//
// Generated by JSON2Apex http://json2apex.herokuapp.com/
//

public class JSON2Apex {

    public class Answers {
        public String answer_exact;
        public String answer_error_margin;
        public String answer_range_start;
        public String answer_range_end;
        public String answer_weight;
        public String numerical_answer_type;
        public String blank_id;
        public String id;
        public String match_id;
        public String answer_text;
        public String answer_match_left;
        public String answer_match_right;
        public String answer_comment;
        public String answer_html;
        public String answer_match_left_html;
        public String answer_comment_html;
    }

    public class Quiz_data {
        public Integer id;
        public String regrade_option;
        public Integer points_possible;
        public String correct_comments;
        public String incorrect_comments;
        public String neutral_comments;
        public String correct_comments_html;
        public String incorrect_comments_html;
        public String neutral_comments_html;
        public String question_type;
        public String question_name;
        public String name;
        public String question_text;
        public List<Answers> answers;
        public String text_after_answers;
        public Integer assessment_question_id;
        public Integer position;
        public String published_at;
    }

    public class Answers_Z {
        public String id;
        public String text;
        public String comments;
        public String comments_html;
        public Integer weight;
        public String html;
    }

    public class Quiz_submission_events {
        public String id;
        public String event_type;
        public Event_data event_data;
        public String created_at;
    }

    public List<Quiz_submission_events> quiz_submission_events;

    public class Event_data {
        public Integer quiz_version;
        public List<Quiz_data> quiz_data;
    }

    public class Answers_Y {
        public Integer id;
        public String text;
        public String html;
        public String comments;
        public String comments_html;
        public Integer weight;
    }

    public class Answers_X {
    }

    public class Event_data_Z {
        public String user_agent;
    }

    public class Event_data_Y {
        public String quiz_question_id;
        public Object answer;
    }


    public static JSON2Apex parse(String json) {
        return (JSON2Apex) System.JSON.deserialize(json, JSON2Apex.class);
    }
}

This is an attempt to handle the inconsistencies in the JSON. I'm not sure whether it'll actually work in practice, but it's worth trying.

If it doesn't work, you have a few options.

• Ideally you would change the JSON to be consistent, but that may not be an option if you're receiving it from a third party.
• Alternatively, you could use JSON.deserializeUntyped() and check the type of each event_data at runtime, but you'd lose the advantages of typed deserialization.
• Or, you could write custom parser code to manually check the value of event_data and parse it appropriately. If you check the Create explicit parse code box on JSON2Apex, you can take the parser code as a starting point.

String.valueOf returns Blob[X] for Blob values. I believe it does it this way because System.debug internally uses String.valueOf, and debugging a potentially non-Unicode stream into a Unicode String could break things. In other words, you can't reliably use String.valueOf unless you can also use it in System.debug and get the output you expect. String.valueOf is always safe to use on a Blob, but Blob.toString may result in an exception if the contents are not a Unicode String.

Let's go with some examples to show how other standard and custom objects behave:

String.valueOf(JSON.createParser('[]'));
// JSONParser:[delegate=common.apex.json.ApexJsonParser@7cde3f62]

String.valueOf(Crypto.generateAesKey(128));
// Blob[16]

String.valueOf([SELECT Id FROM Account LIMIT 1]);
// (Account:{Id=001..., RecordTypeId=012...})

String.valueOf(new MyClassWithoutToString());
// or //
new MyClassWithoutToString().toString();
// MyClasswithoutTostring:[key1=value1, key2=value2]

String.valueOf(new MyClassWithToString());
// Hello There. I work correctly because I have an overridden toString.

String.valueOf(Date.today());    Date.today().format()
// 2016-02-10                    // 2/10/2016

Database.getQueryLocator([SELECT Id FROM Account LIMIT 1])
// Database.QueryLocator[Query=SELECT Id FROM Account LIMIT 1]

String.valueOf(Database.setSavepoint());
// SavepointValue0

String.valueOf(new Component.MyCustomComponent());
// *** Crashes and produces no logs ***

As you can see, you can never quite be sure what you're going to get out of it, unless you're using one of the concrete types listed in the documentation, which is currently: Date, DateTime, Decimal, Integer, and Long.

It does say that it supports "Object" generically, but generally speaking, you'll get the "debug safe" version of a string if you do so, which means it will probably be the wrong value.