i need too array prouducts from higher to lower id (products on firebase) - flutter

Question

class WildWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Obx(()=>GridView.count(
crossAxisCount: 3,
childAspectRatio: .48,
padding: const EdgeInsets.all(15),
mainAxisSpacing: 4.0,
crossAxisSpacing: 10,
children: productController.wild.map((ProductModel product) {
return SingleProductWidget(product: product,);
}).toList())
);
}
}
class SingleProductWidget extends StatelessWidget {
final ProductModel product;
const SingleProductWidget({Key key, this.product}) : super(key: key);
#override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(5)),
child:
Column(
children: [
GestureDetector(
onTap: () {
showDialog(
context: context,
builder: (_) =>Material(
type: MaterialType.transparency,
child: Center(
child:
Padding(
padding:
EdgeInsets.symmetric(vertical:(60)),
child:
CachedNetworkImage(
imageUrl: product.image,
fit: BoxFit.fill,
placeholder: (context, url) => new SpinKitWave(color: Color.fromARGB(255, 0, 53, 145), size: 30,),
errorWidget: (context, url, error) => new Icon(Icons.error),// Fixes border issues
height: double.infinity,
width: double.infinity,
),
),
),
),
);
}, // Image tapped
child:
CachedNetworkImage(
//height: 220,
//width: 140,
imageUrl: product.image,
placeholder: (context, url) => new SpinKitWave(color: Color.fromARGB(255, 0, 53, 145), size: 30,),
errorWidget: (context, url, error) => new Icon(Icons.error),
),
),
Padding(
padding:
const EdgeInsets.symmetric(horizontal:(0)),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Expanded(
child: CustomText(
text: "\$${product.price}",
size: 11,
weight: FontWeight.bold,),),
Expanded(
child:SingleChildScrollView(
scrollDirection: Axis.horizontal,
child: CustomText(
text: product.id,
color: kPrimaryColor,
size: 14,
weight: FontWeight.bold,
),
)
),
IconButton(
icon: Icon(Icons.add_shopping_cart),
onPressed: () {
cartController.addProductToCart(product);
})
],
),
),
],
),
);
}
}
this is products , its shown from lower to higher