Flutter/Dart - Trying to iterate over a map of values // Syntax help needed - flutter

Question

I'm a self-learning beginner at coding, failing at a self-set task. The aim of the task is ultimately to figure out the syntax...but I spent hours now. So...help pls! Warning: I thoroughly confused myself...so don't expect beauty in my attempt.
I want to use iterate over this map:
const marginsCard = [
{
'ID': 0,
'margins': [
{'marginLeft': 0},
{'marginRight': 5},
{'marginBottom': 0},
{'marginTop': 20},
],
},
{
'ID': 1,
'margins': [
{'marginLeft': 5},
{'marginRight': 0},
{'marginBottom': 0},
{'marginTop': 20,},
],
},
{
'ID': 2,
'margins': [
{'marginLeft': 5},
{'marginRight': 0},
{'marginBottom': 0},
{'marginTop': 20,},
],
},
];
The goals are to
iterate over 'ID'
hand over the values for the margins to a constructor method that
hand back a Card with the specified margins
put those Cards in a list.
The function calling the constructor function in its current state:
buildCardElementList(){
cardElementsList = [
...(marginsCard[int.parse('ID')] as List<Map<String,Object>>).map((cardElement){
return buildCardElement(cardElement['marginLeft'], cardElement['marginRight'], cardElement['marginBottom'], cardElement['marginTop']);
}).toList()];
return cardElementsList;
}
There is so much try and eror in this, I'm sure there are multiple issues. Can someone help me out with clean syntax so I can start to understand what I'm doing again?
Thanks!
EDIT // P.S.: I'm leaving out the receiving/constructing function; it's not the issue.

Answer 1

Enjoy ;)
void main() {
final cards = marginsCard.map(_buildCard).toList();
print(cards);
}
Card _buildCard(Map<String, Object> cardElement) {
return Card(
marginLeft: resolveMargin(cardElement, 'marginLeft'),
marginRight: resolveMargin(cardElement, 'marginRight'),
marginBottom: resolveMargin(cardElement, 'marginBottom'),
marginTop: resolveMargin(cardElement, 'marginTop'),
);
}
num resolveMargin(Map<String, Object> cardElement, String marginName) {
final marginElements = cardElement['margins'] as List<Map<String, Object>>;
return marginElements.firstWhere((marginElement) => marginElement.containsKey(marginName))[marginName] as num;
}
class Card {
final num marginLeft, marginRight, marginBottom, marginTop;
Card({required this.marginLeft, required this.marginRight, required this.marginBottom, required this.marginTop});
#override
String toString() => "marginLeft: $marginLeft; marginRight: $marginRight; marginBottom: $marginBottom; marginTop: $marginTop";
}
const marginsCard = [
{
'ID': 0,
'margins': [
{'marginLeft': 0},
{'marginRight': 5},
{'marginBottom': 0},
{'marginTop': 20},
],
},
{
'ID': 1,
'margins': [
{'marginLeft': 5},
{'marginRight': 0},
{'marginBottom': 0},
{'marginTop': 20,},
],
},
{
'ID': 2,
'margins': [
{'marginLeft': 5},
{'marginRight': 0},
{'marginBottom': 0},
{'marginTop': 20,},
],
},
];