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dgarciasquare1dgarciasquare1
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refactor(json): streamline JSON parsing and serialization, replacing deprecated methods
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3 files changed

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‎lib/src/utils/json_handler.dart‎

Lines changed: 21 additions & 159 deletions
Original file line numberDiff line numberDiff line change
@@ -1,169 +1,31 @@
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import 'dart:convert';
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import 'package:flutter_policy_engine/utils/log_handler.dart';
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/// A utility class for handling JSON conversions with generic type support.
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/// Utility for type-safe JSON conversions with generic support.
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///
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/// This class provides methods to convert JSON strings to strongly-typed objects
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/// and vice versa, with proper error handling and type safety.
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/// Provides strongly-typed parsing and serialization to prevent runtime errors
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/// when working with dynamic JSON data structures.
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class JsonHandler {
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/// Converts a JSON string to an object of type T.
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///
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/// [jsonString] - The JSON string to parse
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/// [fromJson] - A factory function that creates an instance of T from a Map
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///
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/// Returns an instance of T if successful, null otherwise.
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///
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/// Example:
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/// ```dart
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/// final policy = JsonHandler.fromJson<Policy>(
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/// jsonString,
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/// (json) => Policy.fromJson(json),
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/// );
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/// ```
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static T? fromJson<T>(
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String jsonString,
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T Function(Map<String, dynamic> json) fromJson,
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) {
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try {
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final Map<String, dynamic> jsonMap = jsonDecode(jsonString);
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return fromJson(jsonMap);
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} on FormatException catch (e) {
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LogHandler.error('JSON format error: $e');
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return null;
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} on TypeError catch (e) {
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LogHandler.error('Type conversion error: $e');
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return null;
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} catch (e) {
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LogHandler.error('Stack trace: ${e.toString()}');
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return null;
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}
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}
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/// Converts a JSON string to a list of objects of type T.
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///
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/// [jsonString] - The JSON string to parse (should be a JSON array)
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/// [fromJson] - A factory function that creates an instance of T from a Map
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///
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/// Returns a List<T> if successful, empty list otherwise.
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///
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/// Example:
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/// ```dart
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/// final policies = JsonHandler.fromJsonList<Policy>(
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/// jsonString,
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/// (json) => Policy.fromJson(json),
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/// );
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/// ```
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static List<T> fromJsonList<T>(
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String jsonString,
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T Function(Map<String, dynamic> json) fromJson,
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) {
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try {
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final List<dynamic> jsonList = jsonDecode(jsonString);
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return jsonList
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.map((item) => fromJson(item as Map<String, dynamic>))
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.toList();
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} on FormatException catch (e) {
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LogHandler.error('JSON format error: $e');
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return [];
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} on TypeError catch (e) {
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LogHandler.error('Type conversion error: $e');
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return [];
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} catch (e) {
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LogHandler.error('Stack trace: ${e.toString()}');
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return [];
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}
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}
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/// Converts an object to a JSON string.
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///
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/// [object] - The object to convert
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/// [toJson] - A function that converts the object to a Map
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/// Converts JSON map to strongly-typed map using provided constructor.
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///
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/// Returns a JSON string if successful, null otherwise.
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///
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/// Example:
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/// ```dart
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/// final jsonString = JsonHandler.toJson<Policy>(
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/// policy,
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/// (policy) => policy.toJson(),
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/// );
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/// ```
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static String? toJson<T>(
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T object,
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Map<String, dynamic> Function(T object) toJson,
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/// Use this when you need to parse a collection of JSON objects into
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/// a specific type while maintaining type safety.
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static Map<String, T> parseMap<T>(
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Map<String, dynamic> jsonMap,
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T Function(Map<String, dynamic>) fromJson,
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) {
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try {
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final Map<String, dynamic> jsonMap = toJson(object);
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return jsonEncode(jsonMap);
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} on TypeError catch (e) {
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LogHandler.error('Type conversion error: $e');
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return null;
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} catch (e) {
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LogHandler.error('Stack trace: ${e.toString()}');
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return null;
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}
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return jsonMap.map(
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(key, value) => MapEntry(key, fromJson(value as Map<String, dynamic>)),
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);
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}
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/// Converts a list of objects to a JSON string.
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///
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/// [objects] - The list of objects to convert
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/// [toJson] - A function that converts an object to a Map
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/// Converts typed map to JSON-serializable format using provided serializer.
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///
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/// Returns a JSON string if successful, null otherwise.
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///
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/// Example:
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/// ```dart
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/// final jsonString = JsonHandler.toJsonList<Policy>(
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/// policies,
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/// (policy) => policy.toJson(),
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/// );
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/// ```
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static String? toJsonList<T>(
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List<T> objects,
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Map<String, dynamic> Function(T object) toJson,
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/// Use this when you need to serialize a collection of typed objects
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/// back to JSON format for storage or transmission.
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static Map<String, dynamic> mapToJson<T>(
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Map<String, T> items,
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Map<String, dynamic> Function(T) toJson,
12526
) {
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try {
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final List<Map<String, dynamic>> jsonList =
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objects.map((object) => toJson(object)).toList();
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return jsonEncode(jsonList);
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} on TypeError catch (e) {
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LogHandler.error('Type conversion error: $e');
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return null;
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} catch (e) {
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LogHandler.error('Stack trace: ${e.toString()}');
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return null;
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}
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}
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/// Safely parses a JSON string and returns the raw Map.
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///
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/// [jsonString] - The JSON string to parse
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///
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/// Returns a Map<String, dynamic> if successful, null otherwise.
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static Map<String, dynamic>? parseJson(String jsonString) {
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try {
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return jsonDecode(jsonString) as Map<String, dynamic>;
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} on FormatException catch (e) {
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LogHandler.error('JSON format error: $e');
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return null;
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} catch (e) {
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LogHandler.error('Stack trace: ${e.toString()}');
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return null;
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}
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}
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/// Validates if a string is valid JSON.
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///
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/// [jsonString] - The string to validate
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///
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/// Returns true if the string is valid JSON, false otherwise.
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static bool isValidJson(String jsonString) {
162-
try {
163-
jsonDecode(jsonString);
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return true;
165-
} catch (e) {
166-
return false;
167-
}
27+
return items.map(
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(key, value) => MapEntry(key, toJson(value)),
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);
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}
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}

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