Scribbles for my bad memory

Flutter’s didChangeDependencies lifecycle method is a common source of redundant network requests and data reloads. Based on real-world code examples from a notes app, let’s explore why this happens and how to fix it.

When Does didChangeDependencies Trigger?

didChangeDependencies in Flutter triggers in these scenarios:

• Immediately after initState()
• When an InheritedWidget ancestor changes
• When the widget's dependencies change

In the provided HomePage code:

@override  
void didChangeDependencies() {  
  super.didChangeDependencies();  
  navigateToPage(currentPageNumber); // ❌ Unconditional call  
}  

This causes duplicate API calls every time the event being triggerd.

The Fix: Initialize-Once Flag

class HomePageState extends State<HomePage> {  
  ...
  bool _isInitialized = false; // Add flag  

  @override  
  void didChangeDependencies() {  
    super.didChangeDependencies();  
    if (!_isInitialized) {  
      _isInitialized = true;  
      navigateToPage(currentPageNumber); // ✅ Only first load  
    }  
  }  
  ...
}  

Why This Works

1. First Load: Initializes data once
2. Subsequent Route Changes: Skips reload unless explicitly refreshed
3. Memory Efficiency: Prevents duplicate API calls (evident from the NotesService cache-less implementation)

Key Takeaways

1. didChangeDependencies isn’t just for initialization
2. Always guard data-loading logic with flags