Create finding-and-converting-json-values-in-dart.dart

tipsandtricks/finding-and-converting-json-values-in-dart/finding-and-converting-json-values-in-dart.dart

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+// 🐦 Twitter                   https://twitter.com/vandadnp
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+// 🤝 Want to support my work?  https://buymeacoffee.com/vandad
+
+import 'dart:developer' as devtools show log;
+
+extension Log on Object? {
+  void log() =>
+      devtools.log(this?.toString() ?? '\x1b[101m\x1b[30mNULL\x1b[0m');
+}
+
+extension Find<K, V, R> on Map<K, V> {
+  R? find<T>(
+    K key,
+    R? Function(T value) cast,
+  ) {
+    final value = this[key];
+    if (value != null && value is T) {
+      return cast(value as T);
+    } else {
+      return null;
+    }
+  }
+}
+
+const json = {
+  'name': 'Foo Bar',
+  'age': 20,
+};
+
+void testIt() {
+  // get the age
+  final String? ageAsString = json.find(
+    'age',
+    (int value) => 'Your age is $value',
+  );
+  ageAsString.log();
+  // force get the name using ! operator
+  final String helloName = json.find(
+    'name',
+    (String name) => 'Hello, $name',
+  )!;
+  helloName.log();
+  // non-existent key
+  final String? address = json.find(
+    'address',
+    (String address) => 'You live at $address',
+  );
+  address.log();
+}