replace characters in string if they matched specific chars in FLUTTER

Question

I am creating a POS where i want to show the items purchased as a text and i intent to store those as a text too. I am separating each item by '\n' character.

Now the problem is that i dont know how to check for text which specifically matches a certain product. I have tried using string.contains method but it is not what i desire.

For example: I have products names like:

Chicken

Chicken Cheese

Now these are two different products but every chicken cheese is going to contain chicken too in it.

So, How can i replace the product

Products are in a list which are further part of a map. However, for this question; you can assume that all the items are stored as a list, Example below:

['chicken', 120],

['chicken Cheeze', 150],

['chicken Cheeze Pizza', 180],

.......................

Than, down in the code i am saving those products as a string (when tapped upon.).

// Gesture Detector is inside a Galleryview which is further part of a row and expanded widgets,
GestureDetector(
     onTap: () {
     //bill items is a string Storing all products.
          billItems += (item[0] +
                    ' :   ' +
                    item[1].toString() + '\n');
               },

P.s: All i want to do is to do something like: "chicken * 3" if chickens are orders 3 times instead of printing it 3 times. Thanks

am not following you , you have to make item description column and beside it a qty box . now if the chicken is matching with different items that fine , you should filter based on first letter not the word it self , so if you start with C all the C items will appear and so on till you get to right the chiken word , then it will filter cheese once you follow the chiken with c . is that what you want ? — Ahmed Amin Shahin
– Ahmed Amin Shahin, Commented Dec 17, 2021 at 21:44
i can share a page where i did that already if you like to see how i did it — Ahmed Amin Shahin
– Ahmed Amin Shahin, Commented Dec 17, 2021 at 21:45
Can you please share some code ? Specifically where you populate the items purchased. — esentis
– esentis, Commented Dec 17, 2021 at 22:06
@esentis I have updated y question with code. Hopefully it will help to understand the problem. Thanks for your time. in case of any confusion please dont hesitate to ask: — Bakhtawar
– Bakhtawar, Commented Dec 18, 2021 at 15:15

esentis · Accepted Answer · 2021-12-19 10:13:18Z

1

So, I have came up with a solution, though I don't know how optimal it is or fast.

I first create a product model to serialize it :

class Product {
  String name;
  double price;
  int count;

  Product({required this.name, required this.price,this.count=0});

  factory Product.fromDynamic(List product) =>
      Product(name: product[0], price: product[1]);

  Map<String, dynamic> toJson() {
    return {"name": name, "price": price,"count":count,};
  }
}

So assuming our products are in this form :

  final originalProducts = [
    ['chicken', 120],
    ['chicken', 135],
    ['chicken', 140],
    ['chicken Cheeze', 150],
    ['chicken Cheeze Pizza', 180],
  ];

I created a List<Product> :

  List<Product> modeledProducts =
      List.generate(originalProducts.length, (i) => Product.fromDynamic(originalProducts[i]));

Next I create a temporary List<String> where I will save any duplicate products found (their names), and I create the final List<Products> which will have unique products with their prices summed up :

  List<String> duplicates = [];

  List<Product> finalProducts = [];

Then we iterate through the modeledProducts to find the duplicates and do the necessary operations :

  for (final product in modeledProducts) {
    if (!duplicates.contains(product.name)) {
      duplicates.add(product.name);
      finalProducts.add(product);
    } else {
      finalProducts.firstWhere((p) => p.name == product.name).price +=
          product.price;
      finalProducts.firstWhere((p) => p.name == product.name).count++;
    }
  }

And now you are ready to use your data :

  for (final fProduct in finalProducts) {
    print(fProduct.toJson());
  }

The above will print :

{name: chicken, price: 395, count: 3}
{name: chicken Cheeze, price: 150, count: 1}
{name: chicken Cheeze Pizza, price: 180, count: 1}

answered Dec 19, 2021 at 10:13

esentis

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2 Comments

Bakhtawar Over a year ago

Hi Esentis, Thanks for your answer. I think it is a complicated and computationally / resource expensive way to overcome the problem.

Bakhtawar Over a year ago

It took me a while to figure it out. The best way of completing the task is by using "MAP<>". We need to store the name as key and price as value. it will assign a new value upon finding the key. Thanks.

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