Flutter: How to detect delete key is pressed on TextField

Question

I am developing a flutter app there the one where a user enters text in the text field and then applying a search from the server database which searches from DB. The issue is that the API call is happening when I input it further, but even when I press the back key, the API call is still happening.

So I want that there is no API call when the user presses the return key.

Here is my code

TextField(
  controller: searchTextController,
  autofocus: true,
  decoration: InputDecoration(
    fillColor: colorWhite.withOpacity(0.20),
    filled: true,
    prefixIcon: Icon(Icons.search),
    hintText: "Search Data...",
    border: InputBorder.none,
    hintStyle: TextStyle(color: Colors.white30),
  ),
  onChanged: (value) {
    updateSearchQuery(query);
  },
  style: TextStyle(color: Colors.white, fontSize: 16.0),
)

Solution 1

The best solution is to wrap your TextField with RawKeyboardListener, like so:

RawKeyboardListener(
      focusNode: _focusNode, // or FocusNode()
      onKey: (event){
        if (event.logicalKey == LogicalKeyboardKey.backspace) {
          // here you can check if textfield is focused
          print('backspace clicked');
        }
        
      },
      child: TextField()
)

You can place any widget inside RawKeyboardListener instead on TextField.

Please refer to this link, Good luck!

Solution 2

You can declare a variable globally;

var val = "";

And then in your onChanged method;

onChanged: (value) {
    if(!val.contains(value))
     updateSearchQuery(query);
    val = value;
  },

You can use it like this. When val contains value(like "aabb" and "aab") do not search.