custom text form field.dart

FormField<String>(
    autovalidateMode: AutovalidateMode.onUserInteraction,
    validator: (value) =>
        (value?.isNotEmpty ?? false) ? null : "Cannot be null",
    onSaved: (value)=> customName = value,
    builder: (state) {
      return Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Expanded(
                child: TextFormField(
                  decoration: const InputDecoration(
                      hintText: "Custom Name"),
                  onChanged: (value) => state.didChange(value),
                ),
              ),
              if (state.isValid) const Icon(Icons.check),
              if (state.hasError)
                const Icon(
                  Icons.close,
                  color: Colors.red,
                ),
            ],
          ),
          if (state.hasError)
            Text(
              state.errorText ?? "",
              style: const TextStyle(color: Colors.red),
            )
        ],
      );
    },
),