How can I filter List<Map<String, dynamic>> to get a value in Flutter?

3
votes

I have a json data and I am loading into List<Map<String, dynamic>> using await jsonDecode..

Example, I have a;

  1. amount = 12500
  2. caliber = 24

and I need to filter the son to get maturity value: 689.19

Also if I have a amount = 12500 and value = 689.19 I need to get caliber which is 24.

How can I filter List> json data to get a value in Flutter?

[
   {"amount": "5000", "caliber": "12", "maturity":  "484.25"},
   {"amount": "5000", "caliber": "24", "maturity":  "275.67"},
   {"amount": "7500", "caliber": "12", "maturity":  "726.38"},
   {"amount": "7500", "caliber": "24", "maturity":  "413.51"},
   {"amount": "10000", "caliber": "12", "maturity":  "968.50"},
   {"amount": "10000", "caliber": "24", "maturity":  "551.35"},
   {"amount": "12500", "caliber": "12", "maturity":  "1210.63"},
   {"amount": "12500", "caliber": "24", "maturity":  "689.19"},
   {"amount": "15000", "caliber": "12", "maturity":  "1452.76"},
   {"amount": "15000", "caliber": "24", "maturity":  "827.03"},
   {"amount": "15000", "caliber": "12", "maturity":  "1694.89"},
   {"amount": "17500", "caliber": "24", "maturity":  "964.87"},
   {"amount": "17500", "caliber": "36", "maturity":  "727.66"},
   {"amount": "17500", "caliber": "48", "maturity":  "613.53"},
   {"amount": "17500", "caliber": "60", "maturity":  "548.44"},
   {"amount": "20000", "caliber": "12", "maturity":  "1937.01"},
   {"amount": "20000", "caliber": "24", "maturity":  "1102.71"}
]

UPDATE: With @Muldec help I finally got it.

First I load above son to List as shown below. And apply @Muldec answer and it worked.

List<Map> myList = List<Map>.from(jsonDecode(jsonFastCalculation) as List);
final item = myList.firstWhere((e) => e['amount'] == '12500' && e['caliber'] == '24');
print(item['maturity']);
1
listfilterflutterwhere

1 Answers

5
votes

You can use the firstWhere or where methods on your list to get the Map element you need or a list of Map depending on your search criteria.

Supposing you are absolutely sure your search criteria will give you only one item (or that you only care of the first item meeting your criteria) here's an example of code with firstWhere:

List<Map<String, dynamic>> myList = ....;

final item = myList.firstWhere((e) => e['amount'] == '12500' && e['caliber'] == '24');
print(item['maturity']);

Finding the caliber based on the amount and the maturity is simply a mater of changing the test in the firstWhere method