如何从 snapshot.data [index] 中的数据创建 map。 颤振/飞镖

Question

I am trying to access and use values that are In my snapshot.data[index]

What I am printing using print(snapshot.data[index]):

I/flutter (11316): Code : LE-0000000002
I/flutter (11316): Description : test_01
I/flutter (11316): Organisation Unit : 01_01_04_01_SA - Shah Alam
I/flutter (11316): Date Reported : 18/09/2020
I/flutter (11316): Status : LE110 - Pending Approval
I/flutter (11316): RunHyperlink : {classid: 25510, id: 2, mad_key: 32835}

this is the code thats feeding data into the snapshot

List<Map<String, dynamic>> incidentList = [
                    for (final json in listNode.map((x) => x.toJson()))
                      {
                        'Code': json['field'][0]['field_value'],
                        'Description': json['field'][1]['field_value'],
                        'Organisation Unit': json['field'][2]['field_value'],
                        'Date Reported': json['field'][3]['field_value'],
                        'Status': json['field'][4]['field_value'],
                        'RunHyperlink' : json['run_hyperlink']
                      }
                  ];


                  final List<String> values =  [];
                  for(final item in incidentList){
                    String groupedElement = "";
                    for(var innerItem in item.entries)
                    {
                      groupedElement += "${innerItem.key} : ${innerItem.value}\n";
                    }
                    values.add(groupedElement);
                  }

                  await WriteCache.setListString(key: 'cache4', value: values);

and this is the future builder:

FutureBuilder(
              future: ReadCache.getStringList(key: 'cache4'),
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  return ListView.builder(
                      itemCount: snapshot.data.length,
                      itemBuilder: (context, index) {
                        return Padding(
                          padding: const EdgeInsets.all(8.0),
                          child: ListTile(
                            onTap: () {

                              print(snapshot.data[index]);
                            },
                            title: Padding(
                              padding: const EdgeInsets.only(top: 10),
                              child: Text(snapshot.data[index],
                                  style: GoogleFonts.poppins(
                                    textStyle: const TextStyle(
                                      fontWeight: FontWeight.normal,
                                      fontSize: 20,
                                    ),
                                  )),
                            ),
                            tileColor: Colors.blueGrey[200],
                            shape: RoundedRectangleBorder(
                                borderRadius: BorderRadius.circular(10)),
                          ),
                        );
                      });
                } else {
                  return const Text("No Data");
                }
              },
            ),

I want to use the "id: value" that is being displayed. I understand that need to create a map to do so but am unsure of how to go about it. Can anyone help me create this map?

The reason why I need to access and use the "id: value" is that I need to pass whatever value is in the "id" to a queryparameter.

Thanks!

Answer 1

At least for a AsyncSnapshot from firestore should be able to access the id just by treating the snapshot.data as a map:

int id = snapshot.data[index]['id']

otherwise you could cast it to a Map like that:

Map snapshotData = snapshot.data[index] as Map<String, int>

Answer 2

try this

   List data = snapshot.data!

you can access id by

data[index].id

Answer 3

Maybe it makes sense to generate models to simplify working with data?
The models below were generated from YAML model descriptions during build process:

lib/stackoverflow.json.dart

class Incident {
  Incident(
      {required this.code,
      required this.description,
      required this.organisationUnit,
      required this.dateReported,
      required this.status,
      required this.runHyperlink});

  factory Incident.fromJson(Map json) {
    return Incident(
      code: json['Code'] == null ? '' : json['Code'] as String,
      description:
          json['Description'] == null ? '' : json['Description'] as String,
      organisationUnit: json['Organisation Unit'] == null
          ? ''
          : json['Organisation Unit'] as String,
      dateReported:
          json['Date Reported'] == null ? '' : json['Date Reported'] as String,
      status: json['Status'] == null ? '' : json['Status'] as String,
      runHyperlink: RunHyperlink.fromJson(json['RunHyperlink'] as Map),
    );
  }

  final String code;

  final String description;

  final String organisationUnit;

  final String dateReported;

  final String status;

  final RunHyperlink runHyperlink;

  static List<Incident> fromJsonList(List json) {
    return json.map((e) => Incident.fromJson(e as Map)).toList();
  }

  Map<String, dynamic> toJson() {
    return {
      'Code': code,
      'Description': description,
      'Organisation Unit': organisationUnit,
      'Date Reported': dateReported,
      'Status': status,
      'RunHyperlink': runHyperlink.toJson(),
    };
  }

  static List<Map<String, dynamic>> toJsonList(List<Incident> list) {
    return list.map((e) => e.toJson()).toList();
  }
}

class RunHyperlink {
  RunHyperlink({required this.classId, required this.id, required this.madKey});

  factory RunHyperlink.fromJson(Map json) {
    return RunHyperlink(
      classId: json['classid'] == null ? 0 : json['classid'] as int,
      id: json['id'] == null ? 0 : json['id'] as int,
      madKey: json['mad_key'] == null ? 0 : json['mad_key'] as int,
    );
  }

  final int classId;

  final int id;

  final int madKey;

  static List<RunHyperlink> fromJsonList(List json) {
    return json.map((e) => RunHyperlink.fromJson(e as Map)).toList();
  }

  Map<String, dynamic> toJson() {
    return {
      'classid': classId,
      'id': id,
      'mad_key': madKey,
    };
  }

  static List<Map<String, dynamic>> toJsonList(List<RunHyperlink> list) {
    return list.map((e) => e.toJson()).toList();
  }
}

lib/stackoverflow.json.yaml

classes:
  Incident:
    fields:
      code:
        type: String
        alias: Code
      description:
        type: String
        alias: Description
      organisationUnit:
        type: String
        alias: Organisation Unit
      dateReported:
        type: String
        alias: Date Reported
      status:
        type: String
        alias: Status
      runHyperlink:
        type: RunHyperlink
        alias: RunHyperlink

  RunHyperlink:
    fields:
      classId:
        type: int
        alias: classid
      id: int
      madKey:
        type: int
        alias: mad_key

pubspec.yaml

dev_dependencies:
  build_runner: any
  object_serializer: ^0.3.6

dart run build_runner build