JSONParse.cls

/*
MIT License

Copyright (c) 2018 open-force

Permission is hereby granted, free of charge, to any person obtaining a copy
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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SOFTWARE.
*/
/**
 * Utility class to streamline parsing nested JSON data structures.
 *
 * @see https://github.com/open-force/jsonparse
 */
public with sharing class JSONParse {

	private static final Pattern ARRAY_NOTATION = Pattern.compile('\\[(\\d+)\\]');

	/**
	 * Every JSONParse instance is a wrapper around some actual data, which we store here.
	 */
	private Object value;

	/**
	 * Create a JSONParse instance from a serialized JSON string.
	 *
	 * @param jsonData
	 */
	public JSONParse(String jsonData) {
		value = JSON.deserializeUntyped(jsonData);
	}

	/**
	 * Create a JSONParse instance from data that has already been unmarshalled from a JSON string.
	 *
	 * @param value
	 */
	private JSONParse(Object value) {
		this.value = value;
	}

	// ---------------------------------------
	// ------ Interactions -------------------
	// ---------------------------------------

	/**
	 * Drill into a nested structure to get to some subtree in the document. We allow the path to include a mix
	 * of array notation and string keys.
	 *
	 * @param path
	 *
	 * @return A new JSONParse wrapper that wraps the targeted subtree.
	 * @throws NotAnArrayException if we try to apply an array notation to a node that isn't an array
	 * @throws NotAnObjectException if we try to apply a map key to a node that isn't an object
	 * @throws MissingKeyException if part of the path can't be resolved because there is no match on that key
	 */
	public JSONParse get(String path) {

		JSONParse currentNode = this; // we start with ourselves and drill deeper

		// drill down through the nested structure
		for(String key : path.split('\\.')) {

			// check to see if we are going to parse this key as a reference to an array item
			Matcher arrayMatcher = ARRAY_NOTATION.matcher(key);

			if(arrayMatcher.matches()) {

				Integer index = Integer.valueOf(arrayMatcher.group(1));
				currentNode = currentNode.asList().get(index);
			}
			else { // otherwise, treat this key as a normal map key

				Map<String, JSONParse> wrappedMap = currentNode.asMap();

				if(!wrappedMap.containsKey(key)) {
					throw new MissingKeyException('No match found for <' + key + '>: ' + wrappedMap.keySet());
				}

				currentNode = wrappedMap.get(key);
			}
		}

		return currentNode;
	}

	/**
	 * Make an assumption that this JSONParse instance wraps a JSON object, and attempt to return a Map of the values.
	 *
	 * @return A Map of JSONParse instances
	 * @throws NotAnObjectException if the internal wrapped value is not a JSON object
	 */
	public Map<String, JSONParse> asMap() {
		if(!isObject()) {
			throw new NotAnObjectException('The wrapped value is not a JSON object:\n' + toStringPretty());
		}

		Map<String, Object> valueAsMap = (Map<String, Object>)value;
		Map<String, JSONParse> wrappers = new Map<String, JSONParse>();
		for(String key : valueAsMap.keySet()) {
			wrappers.put(key, new JSONParse(valueAsMap.get(key)));
		}

		return wrappers;
	}

	/**
	 * Make an assumption that this JSONParse instance wraps a List, and attempt to return an iterable version
	 * of the values.
	 *
	 * @return A List of JSONParse instances, each wrapping one of the List items
	 * @throws NotAnArrayException if the internal wrapped value is not a List instance
	 */
	public List<JSONParse> asList() {
		if(!isArray()) {
			throw new NotAnArrayException('The wrapped value is not a JSON array:\n' + toStringPretty());
		}

		List<JSONParse> wrappers = new List<JSONParse>();
		for(Object item : (List<Object>)value) {
			wrappers.add(new JSONParse(item));
		}

		return wrappers;
	}

	// ---------------------------------------
	// ------ Utility ------------------------
	// ---------------------------------------

	public Boolean isObject() {
		return value instanceof Map<String, Object>;
	}

	public Boolean isArray() {
		return value instanceof List<Object>;
	}

	public String toStringPretty() {
		return JSON.serializePretty(value);
	}

	// ---------------------------------------
	// ------ Value Extraction ---------------
	// ---------------------------------------

	public Blob getBlobValue() {
		if(value instanceof String)
			return EncodingUtil.base64Decode((String)value);
		throw new InvalidConversionException('Only String values can be converted to a Blob: ' + toStringPretty());
	}

	public Boolean getBooleanValue() {
		if(value instanceof Boolean)
			return (Boolean)value;
		return Boolean.valueOf(value);
	}

	public Datetime getDatetimeValue() {
		if(value instanceof Long)
			return Datetime.newInstance((Long)value);
		if(value instanceof String)
			return Datetime.valueOfGmt(((String)value).replace('T', ' '));
		throw new InvalidConversionException('Only Long and String values can be converted to a Datetime: ' + toStringPretty());
	}

	public Date getDateValue() {
		if(value instanceof Long)
			return Datetime.newInstance((Long)value).dateGmt();
		if(value instanceof String)
			return Date.valueOf((String)value);
		throw new InvalidConversionException('Only Long and String values can be converted to a Date: ' + toStringPretty());
	}

	public Decimal getDecimalValue() {
		if(value instanceof Decimal)
			return (Decimal)value;
		if(value instanceof String)
			return Decimal.valueOf((String)value);
		throw new InvalidConversionException('This value cannot be converted to a Decimal: ' + toStringPretty());
	}

	public Double getDoubleValue() {
		if(value instanceof Double)
			return (Double)value;
		if(value instanceof String)
			return Double.valueOf((String)value);
		throw new InvalidConversionException('This value cannot be converted to a Double: ' + toStringPretty());
	}

	public Id getIdValue() {
		if(value instanceof String)
			return Id.valueOf((String)value);
		throw new InvalidConversionException('This value cannot be converted to an Id: ' + toStringPretty());
	}

	public Integer getIntegerValue() {
		if(value instanceof Integer)
			return (Integer)value;
		if(value instanceof Decimal)
			return ((Decimal)value).intValue();
		if(value instanceof String)
			return Integer.valueOf((String)value);
		throw new InvalidConversionException('This value cannot be converted to an Integer: ' + toStringPretty());
	}

	public Long getLongValue() {
		if(value instanceof Long)
			return (Long)value;
		if(value instanceof Decimal)
			return ((Decimal)value).longValue();
		if(value instanceof String)
			return Long.valueOf((String)value);
		throw new InvalidConversionException('This value cannot be converted to a Long: ' + toStringPretty());
	}

	public String getStringValue() {
		if(isObject() || isArray())
			throw new InvalidConversionException('Objects and arrays are not Strings: ' + toStringPretty());
		if(value instanceof String)
			return (String)value;
		return String.valueOf(value);
	}

	public Time getTimeValue() {
		if(value instanceof Long)
			return Datetime.newInstance((Long)value).timeGmt();
		if(value instanceof String)
			return Datetime.valueOfGmt(((String)value).replace('T', ' ')).timeGmt();
		throw new InvalidConversionException('Only Long and String values can be converted to a Time: ' + toStringPretty());
	}

	public Object getValue() {
		return value;
	}

	// ---------------------------------------
	// ------ Exceptions ---------------------
	// ---------------------------------------
	public class NotAnObjectException extends Exception {}
	public class NotAnArrayException extends Exception {}
	public class MissingKeyException extends Exception {}
	public class InvalidConversionException extends Exception {}
}