created alram form widget placeholders

lib/widgets/time_selector.dart

@@ -12,6 +12,7 @@ class TimeSelector extends StatefulWidget {
     required this.dueDateController,
     required this.dueTimeController,
     this.formKey,
+    this.onChanged,
   });
 
   final DateTime? initialDueDateTime;
@@ -19,6 +20,7 @@ class TimeSelector extends StatefulWidget {
   final FocusNode? nextFocusNode;
   final TextEditingController dueDateController;
   final TextEditingController dueTimeController;
+  final void Function(DateTime dateTime)? onChanged;
 
   @override
   State<TimeSelector> createState() => _TimeSelectorState();
@@ -48,7 +50,18 @@ class _TimeSelectorState extends State<TimeSelector> {
           child: TextFormField(
             focusNode: dueDateFocusNode,
             controller: widget.dueDateController,
-            onChanged: maybeEnableDueTime,
+            onChanged: (value) {
+              maybeEnableDueTime(value);
+              if (dateTimeValidator(value) == null &&
+                  widget.onChanged != null) {
+                final dateTime = DateTime.tryParse(
+                  '$value ${widget.dueTimeController.text}'.trim(),
+                );
+                if (dateTime != null) {
+                  widget.onChanged!(dateTime);
+                }
+              }
+            },
             onFieldSubmitted: (_) {
               isDueTimeEnabled
                   ? dueDateFocusNode.nextFocus()
@@ -85,6 +98,16 @@ class _TimeSelectorState extends State<TimeSelector> {
             onFieldSubmitted: (_) => dueTimeFocusNode.nextFocus(),
             controller: widget.dueTimeController,
             enabled: isDueTimeEnabled,
+            onChanged: (value) {
+              if (timeValidator(value) == null && widget.onChanged != null) {
+                final dateTime = DateTime.tryParse(
+                  '${widget.dueDateController.text} $value'.trim(),
+                );
+                if (dateTime != null) {
+                  widget.onChanged!(dateTime);
+                }
+              }
+            },
             decoration: InputDecoration(
               label: Text('Due Time'),
               suffixIcon: IconButton(