No such method error while calling a function - firebase

Question

I retrieved products data from Firebase for my E-commerce homepage through future builder. I've created another screen that displays more information on a product when the user clicks on a product from the E-commerce homepage.To navigate to more information screen i created a function called showProduct and called it with a button, but when the button id pressed it shows
NoSuchMethodError: The method '[]' was called on null.Receiver: null Tried calling .
The showProduct function ] was also used on the vendor profile page where the products shown are shown in gridview and when clicked on any product from the vendors's profile.The showProduct function works and open more information screen.
E-commerce Homepage:
c
lass Shop extends StatefulWidget {
final Prod products;
final User currentUser;
final String prodId;
final String onwerId;
Shop({ this.currentUser,
this.prodId,
this.products,
this.onwerId});
#override
_ShopState createState() => _ShopState( prodId: this.prodId,products: this.products,ownerId:this.onwerId);
}
class _ShopState extends State<Shop> {
String postOrientation = "grid";
String shopOrientation = "grid";
bool isFollowing = false;
bool isLoading = false;
String uid="";
String prodId;
String ownerId;
Prod products;
_ShopState({
this.prodId, this.products,this.ownerId,
});
#override
void initState() {
super.initState();
showProduct;
}
Future getProducts()async {
var firestore = Firestore.instance;
QuerySnapshot snap = await firestore.collectionGroup("userProducts").getDocuments();
return snap.documents;
}
Future<Null>getRefresh()async{
await Future.delayed(Duration (seconds : 3));
setState(() {
getProducts();
});
}
showProduct(context) {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ProductScreen(
prodId: prodId,
userId: ownerId,
),
),
);
}
#override
Widget build(BuildContext context) {
return
Scaffold(
appBar: AppBar(backgroundColor: kSecondaryColor,
title: Text( 'Shop',
style: TextStyle(
fontFamily :"MajorMonoDisplay",
fontSize: 35.0 ,
color: Colors.white),),
iconTheme: new IconThemeData(color: kSecondaryColor),
),
backgroundColor: kPrimaryColor,
body:FutureBuilder(
future: getProducts(),
builder: (context,snapshot)
{
if (snapshot.connectionState == ConnectionState.waiting) {
return Center(child: circularProgress(),);
} else {
return
RefreshIndicator(
onRefresh: getRefresh,
child: ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
var ourdata = snapshot.data[index];
return
Container(
height: 500,
margin: EdgeInsets.only(
top: 1.0, left: 10.0, right: 10.0, bottom: 1.0),
child: Column( children: <Widget>[
SizedBox( height:1.0,),
Stack(
children: <Widget>[
Container(
child:Row(
children: <Widget>[
Expanded(
child: Container(
height: 400.0,
child: ClipRRect(borderRadius: BorderRadius.circular(20.0),
child: cachedNetworkImage(ourdata.data['shopmediaUrl'],
),
),
),
),
],
),
),
Expanded(
child: Positioned(
bottom: 10,
left: 10,
child: Container(
height: 40,
width: 40,
child: ClipRRect(
borderRadius: BorderRadius.circular(40.0),
child: Image.network(ourdata.data['photoUrl'],)),
),
),
),
Expanded(
child: Positioned(
bottom: 20,
left: 60,
child: Container(
child: Text(ourdata.data['username'],style: TextStyle(color: Colors.white,fontWeight:FontWeight.bold),),
),
),
),
Container(
alignment: Alignment.bottomRight,
child: GFButton(
onPressed: () => showProduct(context) ,
text: "More",
icon: Icon(Icons.card_travel),
shape: GFButtonShape.pills,
),
),
],
),
Row(
children: <Widget>[
Container(
child: Text(ourdata.data['productname'],style: TextStyle(color: kText,fontSize: 30.0,fontWeight:FontWeight.bold),),
),
],
),
Row(
children: <Widget>[
Container( child: Text('₹',style: TextStyle(color: kText,)),
),
Container(
child: Text(ourdata.data['price'],style: TextStyle(color: kText,fontSize: 20.0,fontWeight:FontWeight.bold),),
),
],
),
Divider(color: kGrey,),
],
),
);
}
)
);
}
}
),
floatingActionButton: FloatingActionButton(
backgroundColor: Colors.black38,
onPressed: ()
async{ Navigator.push(context, MaterialPageRoute(builder: (context) =>Uploadecom(currentUser: currentUser, )));
},
child: Icon(Icons.add_box),
),
);
}
}
This is the gridview on the vendor's profile.
class ProductTile extends StatelessWidget {
final Prod products;
ProductTile(this.products);
showProduct(context) {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ProductScreen(
prodId: products.prodId,
userId: products.ownerId,
),
),
);
}
#override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () => showProduct(context),
child: cachedNetworkImage(products.shopmediaUrl),
);
}
}
If you need more codes please ask me.