Sets in Dart

main.dart

void main() {
  Set<String> smartTags = {};
  
  final List<Product> productsToPullTagsFrom = [
    Product(productName: 'Product A', bvTags: ['tag 1']),
    Product(productName: 'Product B', bvTags: ['tag 2', 'tag 3']),
    Product(productName: 'Product C', bvTags: ['tag 1', 'tag 3']),
    Product(productName: 'Product D'), // no tags, and in fact, tags are null
    Product(productName: 'Product E', bvTags: []),
    Product(productName: 'Product F', bvTags: ['tag 1', 'tag 2', 'tag 3', 'tag 4']),
    Product(productName: 'Product G', bvTags: ['tag 1', 'tag 1', 'tag 1', 'tag 1', 'tag 1', 'tag 1', 'tag 1'])
  ];
  
  productsToPullTagsFrom.forEach((p) {
    if (p.bvTags != null) {
      if (p.bvTags!.isNotEmpty) {
        smartTags.addAll(p.bvTags!); // avoids an inner-loop required. addAll will individually add the elements of one list to another.
      }
    }
  });
  
  // out of 6 products, there are only 4 unique tags. 
  // Try changing this to see if you can avoid the error
  final int expectedLength = 16;
  try {
    assert(smartTags.length == expectedLength);  
  } on AssertionError {
    print('***\nIf you see this message, we dont have the right number of tags in our Set.\n\nLength of smart tags is ${smartTags.length}, but we asserted it would be $expectedLength\n***');
  } catch (e) {
    // some other sort of error
    print(e);
  }
  
  print('Smart tags in Set<String> smartTags is: [${smartTags.join(', ')}]');
}

class Product {
  final String productName;
  final List<String>? bvTags;
  
  Product({required this.productName, this.bvTags});
}