Dart, compare two lists and return element from first list that does not exist in second list-CodePudding

I have two lists,

List first = [{'name':'ABC','serialNumber':'ABC-124-353'},
{'name':'XYZ','serialNumber':'XYZ-123-567'},
{'name':'GRE', 'serialNumber': 'GRE-290-128'}];

List second = [{'name':'PQR','serialNumber':'PQR-D123-SII23'},{'name':'GAR','serialNumber':'GAR-G43-432'},
{'name':'MNOP','serialNumber':'XYZ-123-567'}];

Is there any easier way to compare first list and second list by serialNumber. such that element from first list that doesn't exist in second list are outputted as a result.

So in this case

[{'name':'ABC','serialNumber':'ABC-124-353'},{'name':'GRE', 'serialNumber': 'GRE-290-128'}]

from first list is desired output, because ABC-124-353 and GRE-290-128 doesn't exist in list second

CodePudding user response：

I'd make a set of the serial numbers of the second list, so that you can do efficient contains checks. So:

var secondListSerials = {for (var entry in secondList) entry["serialNumber"]};
var firstListOnly = [for (var entry in firstList) 
  if (!secondListSerials.contains(entry["serialNumber"]) entry
];

CodePudding user response：

Another solution would be to use where on your first List to check if the serialNumber is contained in the second list:

final secondSerials = second.map((item) => item['serialNumber']).toSet();
print(first.where((item) => !secondSerials.contains(item['serialNumber'])).toList());