Add the quantity of items (e-commerce/shop app)

Question

i'm currently developing an e-commerce app,

i'm trying to increase the quantity of items the user are trying to shop and then show them in the "items Cart" but instead, i get multiple times the same item.

cart_Items_Screen

here's the code i'm using for it:

FlatButton(
                onPressed: () {
                  _addToCart(context, this.widget.product);
                },
                textColor: Colors.redAccent,
                child: Row(
                  children: [
                    Text('Add to Cart'),
                    IconButton(
                        icon: Icon(Icons.shopping_cart), onPressed: () {}),
                  ],
                ),
              ),

_addToCart(BuildContext context, Product product) async {
    var result = await _cartService.addToCart(product);
    if (result > 0) {
      print(result);
      _showSnackMessage(Text(
        'Item added to cart successfully!',
        style: TextStyle(color: Colors.green),
      ));
    } else {
      _showSnackMessage(Text(
        'Failed to add to cart!',
        style: TextStyle(color: Colors.red),
      ));
    }
  }

addToCart(Product product) async {
    List<Map> items =
        await _repository.getLocalByCondition('carts', 'productId', product.id);
    if (items.length > 0) {
      product.quantity = items.first['productQuantity'] + 1;
      return await _repository.updateLocal(
          'carts', 'productId', product.toMap());
    }
    print(items);
    product.quantity = 1;
    return await _repository.saveLocal('carts', product.toMap());
  }

Have anyone has experience something like this? Can anyone help me?

Answer 1

What are you using to keep your items? Local database or just a list? In any case you need to check your items contains first, then if it is you need update only quantity if it is not you need to add as a new element. I mean as I understand you check this with items.length > 0 and it looks too general, items.contains('productId') would be more specific to use.