How do I access the value of a given key in a nested Map in Dart?

Question

I am new in Dart and I have been trying to access the value of "farm_size" key in the following piece of code but unsuccessful. I can access up to "farms" like this

print(myData1[0]["farms"]);

But not any further. Any help will be appreciated. Thanks.

void main() {
  var myData1 = [
  {
    "id": 1,
    "first_name": "Jordan",
    "sur_name": "Zamunda",
    "member_n0": "AA1",
    "gender": "male",
    "phone": "123456789",
    "email": "jordan@example.com",
    "farms": [
      {"id": 1, "farm_name": "SOUTH_FARM", "farm_size": "160 acres"},
      {"id": 2, "farm_name": "NORTH_FARM", "farm_size": "190 acres"}
    ]
  }
];

  print(myData1[0]["farms"]);

}

Huthaifa Muayyad · Accepted Answer · 2021-08-15T17:48:08.967

2

inside farms, there is a list of more maps, to access those maps, you need to specify the index of the map you, for example we want to get the first map, we type:

print(myData1[0]["farms"][0]);
//this will print => {"id": 1, "farm_name": "SOUTH_FARM", "farm_size": "160 acres"}

//to get the name of this farm, you use the key 'farm_name' now:
print(myData1[0]["farms"][0]['farm_name']);
//prints=> SOUTH_FARM

If you're running it in dartpad, this will work:

void main() {
  
  var myData1 = [
  {
    "id": 1,
    "first_name": "Jordan",
    "sur_name": "Zamunda",
    "member_n0": "AA1",
    "gender": "male",
    "phone": "123456789",
    "email": "jordan@example.com",
    "farms": [
      {"id": 1, "farm_name": "SOUTH_FARM", "farm_size": "160 acres"},
      {"id": 2, "farm_name": "NORTH_FARM", "farm_size": "190 acres"}
    ]
  }
];
  List<Map<String,dynamic>> _list = myData1[0]["farms"]as List<Map<String,dynamic>> ;
  
  print(_list[0]['farm_name']);


}

edited Aug 15 '21 at 17:48

answered Aug 15 '21 at 17:35

Huthaifa Muayyad

11,321
3
17
49

I tried that but got this error "Error: The operator '[]' isn't defined for the class 'Object?'. – willy Aug 15 '21 at 17:37
Any idea on how a Model class with those fields would look like? – willy Aug 16 '21 at 06:13
You would have a model for the user\farmer. You also would need a model for the separate `Farm`. Inside the `user` model, besides gender and phone..etc you would have a `List` that contains individual `Farm` objects. – Huthaifa Muayyad Aug 16 '21 at 07:12
1

Sure! Thanks you. – willy Aug 16 '21 at 07:38

score 1 · Answer 2 · answered Aug 15 '21 at 18:25

1

try this

List m = myData1[0]['farms'] as List;

 print(m[0]['id']);

answered Aug 15 '21 at 18:25

Sintayew Zebene

61
4

How do I access the value of a given key in a nested Map in Dart?

2 Answers2