Flutter null safety: The method '[]' can't be unconditionally invoked because the receiver can be 'null'

Question

I am trying to pass data from a GridView builder with index value but getting following error:

The method '[]' can't be unconditionally invoked because the receiver can be 'null'.
Try making the call conditional (using '?.') or adding a null check to the target ('!').

On this line:

itemBuilder: (BuildContext ctxt, int index) {
   return ProductCard(
     product: productsProvider.data[index],
   );
}),

However if i put null check operator(!) it shows another error:

itemBuilder: (BuildContext ctxt, int index) {
   return ProductCard(
      product: productsProvider.data![index],
   );
}),


The operator '[]' isn't defined for the type 'AsyncData<ProductCategoryDetailsModel>'.
Try defining the operator '[]'.

I have tried placing null safety operators (? and !) every possible place but couldn't find any way. Please help!

@override
Widget build(BuildContext context, ScopedReader watch) {
  AsyncValue<ProductCategoryDetailsModel>? productsProvider =
    watch(productCategoryDetailsProvider);

return Scaffold(
 
  body: Center(
    child: SingleChildScrollView(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          productsProvider!.when(
              data: (data) {
                return SingleChildScrollView(
                  child: Column(
                    children: [
                    
                      Container(
                        margin: EdgeInsets.all(20),
                        child: GridView.builder(
                            itemCount: data.data!.data!.length,
                            physics: BouncingScrollPhysics(),
                            gridDelegate:
                                SliverGridDelegateWithMaxCrossAxisExtent(
                                    maxCrossAxisExtent: 180,
                                    childAspectRatio: 3 / 4,
                                    crossAxisSpacing: 10,
                                    mainAxisSpacing: 10),
                            shrinkWrap: true,
                            itemBuilder: (BuildContext ctxt, int index) {
                              return ProductCard(
                                product: productsProvider.data[index],
                              );
                            }),
                      ),
                    ],
                  ),
                );
              },
              loading: () => Center(
                    child: CircularProgressIndicator(),
                  ),
              error: (error, stack) => Text(error.toString())),
          ],
        ),
      ),
    ),
  );
 }
}

The new version of flutter insted of using : productsProvider.data[index] try : productsProvider.get(index) . — Salah dine Maham, Mar 14 '22 at 15:59

The Anonymous Koder · Answer 1 · 2021-07-06T03:02:44.633

0

Try using the operator List?['property'] to access the Map

itemBuilder: (BuildContext ctxt, int index) {
   return ProductCard(
      product: productsProvider.data?[index],
        //edit in the above line data![index] to data?[index]
   );
}),

edited Jul 06 '21 at 03:02

answered Jul 05 '21 at 11:20

The Anonymous Koder

552
3
12

Could you please relate to my code – Golam Sarwar Shakil Jul 05 '21 at 14:00

score 0 · Answer 2 · answered Jul 05 '21 at 16:05

0

Oh! i was passing wrong info. The right code is:

 itemBuilder: (BuildContext ctxt, int index) {
     return ProductCard(
       product: data.data!.data![index],
     );
 }),

answered Jul 05 '21 at 16:05

Golam Sarwar Shakil

115
4
9

Flutter null safety: The method '[]' can't be unconditionally invoked because the receiver can be 'null'

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