Change text fragment in TextFormField and make it static (not changeable) Flutter

I have added the text that is displayed in the TextFormField. I need to change the text size of not everything, but only KWh, make it smaller + can the € and KWh values ​​be made static so that they cannot be changed?

code

TextFormField(
            keyboardType: TextInputType.number,
            controller: _priceController
              ..text = '€' + widget.price.toStringAsFixed(2) + ' KWh',
            style: widget.textStyle,
            textAlign: TextAlign.center,
            decoration: const InputDecoration(
              contentPadding: EdgeInsets.zero,
              border: InputBorder.none,
            ),
          ),

>Solution :

This is why Suffix and Prefix are provided in InputDecoration.

To use them for your desired output, do as:

TextFormField(
  keyboardType: TextInputType.number,
  controller: _priceController
      ..text = widget.price.toStringAsFixed(2),
  style: widget.textStyle,
  textAlign: TextAlign.center,
  decoration: const InputDecoration(
  prefix: Text('€',
      style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
  suffix: Text('KWh',
      style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
  contentPadding: EdgeInsets.zero,
  border: InputBorder.none,
  ),
),

You can change the color, fontSize, fontWeight or any such TextStyle property by using widgets for Suffix and Prefix. Prefix and Suffix stay static and can’t be changed/Edited by the user.

Output:

Do Remember, Suffix is placed at the end of the TextFormField, so, you’ve to adjust the its width according to that.

Else, it will look like this with a full width TextFormField: