I am trying to implement a Cart System using Riverpod to manage the state of the Cart.

This is the part where the user clicks on a product to add it to the cart:

   GestureDetector(
                      child: Icon(Icons.shopping_cart),
                      onTap: () async {
                        print("cart test");
                        //create new cart item
                        Cart cartItem = new Cart(
                          id: product.id,
                          name: product.name,
                          oldPrice: product.oldPrice,
                          price: product.price,
                          imageUrl: product.imageUrl,
                          category: product.category,
                          quantity: 1
                        );
                        var cartInstance = context.read(cartListProvider);
                        if(isExistsInCart(cartInstance.state,cartItem))
                          context.read(cartListProvider).edit(cartItem,1);
                        else
                          {
                            context.read(cartListProvider).add(cartItem);//if already available in cart, just increase quantity
                            var string = json.encode(context.read(cartListProvider).state);
                            await storage.write(key: cartKey, value: string);
                            
                          }




                      },
                    )

Here you have the provider class:

import 'package:cart_system_riverpod/models/cart.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

final cartListProvider = StateNotifierProvider((ref){

  return CartList([]); //init empty cart

});

I have also added ProviderScope to the top of the Widgets tree.

My issue is that I am getting errors implementing:

cartInstance = context.read(cartListProvider)

and

context.read(cartListProvider).edit(cartItem,1);

always at the read(...) part

The editor shows the hint The method 'read' isn't defined for the type 'BuildContext'.

CodePudding user response：

From Riverpod 1.0.0 context.read was removed in favour of ref.read

So replace context.read with ref.read

Try this:

    Consumer(
      builder: (context, ref, _) {
        return GestureDetector(
          child: Icon(Icons.shopping_cart),
          onTap: () async {
            print("cart test");
            //create new cart item
            Cart cartItem = new Cart(
                id: product.id,
                name: product.name,
                oldPrice: product.oldPrice,
                price: product.price,
                imageUrl: product.imageUrl,
                category: product.category,
                quantity: 1);
            var cartInstance = ref.read(cartListProvider);
            if (isExistsInCart(cartInstance.state, cartItem))
              ref.read(cartListProvider).edit(cartItem, 1);
            else {
              ref.read(cartListProvider).add(
                  cartItem); //if already available in cart, just increase quantity
              var string = json.encode(ref.read(cartListProvider).state);
              await storage.write(key: cartKey, value: string);
            }
          },
        );
      },
    );

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