如何通过 Map 的特定键合并/加入两个 Map 列表？

Question

如何通过特定键合并两个 List

例如：

List

List<Map<String, dynamic>> Wallet = [
  {
    "id": 1,
    "value": 153030
  },
  {
    "id": 2,
    "value": 817831
  },
  {
    "id": 3,
    "value": 25
  },
  {
    "id": 4,
    "value": 660
  },
  {
    "id": 5,
    "value": 132
  },
  {
    "id": 7,
    "value": 145
  }
];

List<Map<String, dynamic>> Currencies = [
  {
    "id": 1,
    "name": "coin",
    "desc": "Dummytext.",
    "order": 101,
    "icon": "https://icon1.png"
  },
  {
    "id": 2,
    "name": "karma",
    "desc": "Dummytext.",
    "order": 102,
    "icon": "https://icon2.png"
  },
  {
    "id": 3,
    "name": "laurel",
    "desc": "Dummytext.",
    "order": 104,
    "icon": "https://icon3.png"
  },
  {
    "id": 4,
    "name": "diamonds",
    "desc": "Dummytext.",
    "order": 100,
    "icon": "https://icon4.png"
  },
  {
    "id": 5,
    "name": "tears",
    "desc": "Dummytext.",
    "order": 402,
    "icon": "https://icon5.png"
  },
  {
    "id": 6,
    "name": "shard",
    "desc": "Dummytext.",
    "order": 409,
    "icon": "https://icon6.png"
  },
  {
    "id": 7,
    "name": "relict",
    "desc": "Dummytext.",
    "order": 400,
    "icon": "https://icon7.png"
  },
  {
    "id": 9,
    "name": "seal",
    "desc": "Dummytext.",
    "order": 403,
    "icon": "https://icon9.png"
  },
  {
    "id": 10,
    "name": "silver",
    "desc": "Dummytext.",
    "order": 405,
    "icon": "https://icon10.png"
  }
];

合并后的列表我要找的操作后

List<Map<String, dynamic>> ExtendedWallet = [
  {
    "id": 1,
    "value": 153030,
    "name": "coin",
    "desc": "Dummytext.",
    "order": 101,
    "icon": "https://icon1.png"
  },
  {
    "id": 2,
    "value": 817831,
    "name": "karma",
    "desc": "Dummytext.",
    "order": 102,
    "icon": "https://icon2.png"
  },
  {
    "id": 3,
    "value": 25,
    "name": "laurel",
    "desc": "Dummytext.",
    "order": 104,
    "icon": "https://icon3.png"
  },
  {
    "id": 4,
    "value": 660,
    "name": "diamonds",
    "desc": "Dummytext.",
    "order": 100,
    "icon": "https://icon4.png"
  },
  {
    "id": 5,
    "value": 132,
    "name": "tears",
    "desc": "Dummytext.",
    "order": 402,
    "icon": "https://icon5.png"
  },
  {
    "id": 7,
    "value": 145,
    "name": "relict",
    "desc": "Dummytext.",
    "order": 400,
    "icon": "https://icon7.png"
  }
];

请注意，“id”在 Wallet 中 not 的 Currencies 地图将不会被使用，将被跳过。

希望你们能得到我的意见，并能帮助我解决这个问题！

Answer 1

你可以使用singleWhere找到cross id，然后使用map进行合并，这里修复的问题是飞镖垫here

  List<Map<String, dynamic>> wallet = [
    {"id": 1, "value": 153030},
    {"id": 2, "value": 817831},
    {"id": 3, "value": 25},
    {"id": 4, "value": 660},
    {"id": 5, "value": 132},
    {"id": 7, "value": 145}
  ];

  List<Map<String, dynamic>> currencies = [
    {
    "id": 1,
    "name": "coin",
    "desc": "Dummytext.",
    "order": 101,
    "icon": "https://icon1.png"
  },
  {
    "id": 2,
    "name": "karma",
    "desc": "Dummytext.",
    "order": 102,
    "icon": "https://icon2.png"
  },
  {
    "id": 3,
    "name": "laurel",
    "desc": "Dummytext.",
    "order": 104,
    "icon": "https://icon3.png"
  },
  {
    "id": 4,
    "name": "diamonds",
    "desc": "Dummytext.",
    "order": 100,
    "icon": "https://icon4.png"
  },
  {
    "id": 5,
    "name": "tears",
    "desc": "Dummytext.",
    "order": 402,
    "icon": "https://icon5.png"
  },
  {
    "id": 6,
    "name": "shard",
    "desc": "Dummytext.",
    "order": 409,
    "icon": "https://icon6.png"
  },
  {
    "id": 7,
    "name": "relict",
    "desc": "Dummytext.",
    "order": 400,
    "icon": "https://icon7.png"
  },
  {
    "id": 9,
    "name": "seal",
    "desc": "Dummytext.",
    "order": 403,
    "icon": "https://icon9.png"
  },
  {
    "id": 10,
    "name": "silver",
    "desc": "Dummytext.",
    "order": 405,
    "icon": "https://icon10.png"
  }
  ];

  var result = currencies.map((e) {
    Map<String, dynamic> founded =
        wallet.singleWhere((w) => w['id'] == e['id'], orElse: (){return null;});

    if (founded != null) {
      e.addEntries(founded.entries);
      return e;
    } else {
      return null;
    }
  }).toList();

  print(result);
}

Answer 2

您可以使用此代码获得所需的结果

import 'dart:convert';
void main() {  
  List<Map<String, dynamic>> Wallet = [
  {
    "id": 1,
    "value": 153030
  },
  {
    "id": 2,
    "value": 817831
  },
  {
    "id": 3,
    "value": 25
  },
  {
    "id": 4,
    "value": 660
  },
  {
    "id": 5,
    "value": 132
  },
  {
    "id": 7,
    "value": 145
  }
];
  
  List<Map<String, dynamic>> Currencies = [
  {
    "id": 1,
    "name": "coin",
    "desc": "Dummytext.",
    "order": 101,
    "icon": "https://icon1.png"
  },
  {
    "id": 2,
    "name": "karma",
    "desc": "Dummytext.",
    "order": 102,
    "icon": "https://icon2.png"
  },
  {
    "id": 3,
    "name": "laurel",
    "desc": "Dummytext.",
    "order": 104,
    "icon": "https://icon3.png"
  },
  {
    "id": 4,
    "name": "diamonds",
    "desc": "Dummytext.",
    "order": 100,
    "icon": "https://icon4.png"
  },
  {
    "id": 5,
    "name": "tears",
    "desc": "Dummytext.",
    "order": 402,
    "icon": "https://icon5.png"
  },
  {
    "id": 6,
    "name": "shard",
    "desc": "Dummytext.",
    "order": 409,
    "icon": "https://icon6.png"
  },
  {
    "id": 7,
    "name": "relict",
    "desc": "Dummytext.",
    "order": 400,
    "icon": "https://icon7.png"
  },
  {
    "id": 9,
    "name": "seal",
    "desc": "Dummytext.",
    "order": 403,
    "icon": "https://icon9.png"
  },
  {
    "id": 10,
    "name": "silver",
    "desc": "Dummytext.",
    "order": 405,
    "icon": "https://icon10.png"
  }
];
  
 List<Map<String, dynamic>> ExtendedWallet = [];
  Currencies.forEach((element){
      Wallet.forEach((e){
        if(e["id"]==element["id"]){
          ExtendedWallet.add(
            getExtendedWallet(e["id"]
                              ,e["value"]
                              ,element["name"]
                              ,element["desc"],
                              element["order"],
                              element["icon"])
          );
        }
      });
    
  });
  print(json.encode(ExtendedWallet).toString());
}

 Map<String, dynamic> getExtendedWallet(int id,int value,String name,String desc,int order,String icon){
  final Map<String, dynamic> data = new Map<String, dynamic>();
    data["id"] = id;
    data["value"] = value;
    data["name"] = name.toString();
    data["desc"] = desc.toString();
    data["order"] = order;
    data["icon"] = icon.toString();
    return data; 
}