Question

我有田地服务器名称、服务器IP、数据库和港口。我需要服务器名称领域为下级,其价值为serverName1和serverName2,分别来自List<Map<String, Map<String, String>>>。然后,如果用户选择其中一种,则其他领域应当更新适当的附加价值(Server IP, Database, Port)。我如何这样做?

class GlobalsProvider {

List<Map<String, Map<String, String>>> getServers() {
  final serverList = [{
     serverName1 : {
       Server IP :  ip1 ,
       Database :  db1 ,
       Port :  port1 
    },
     serverName2 : {
       Server IP :  ip2 ,
       Database :  db2 ,
       Port :  port2 
    }
  }];

  return serverList;
}

}

@override
  Widget build(BuildContext context) {
    return Consumer<GlobalsProvider>(
        builder: (context, value, child) => Scaffold(
            appBar: AppBar(
              title: const Text( Login ),
              centerTitle: true,
              actions: [
                IconButton(
                    onPressed: () {},
                    icon: const Icon(Icons.add)
                ),
              ],
            ),
            body: Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.start,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: [
                  Expanded(
                    flex: 2,
                    child: Visibility(
                      visible: true, 
                      child: Row(
                        children: [
                          const Expanded(child: Text( Server Name: )),
                          DropdownButton(
                            //? Not sure how to do this part
                          )
                        ],
                      ),
                    ),
                  ),
                  Expanded(
                    flex: 2,
                    child: Visibility(
                      visible: true, 
                      child: Row(
                        children: [
                          const Expanded(child: Text( Server IP: )),
                          Expanded(
                            child: TextField(
                              controller: serverIPController,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                  Expanded(
                    flex: 2,
                    child: Visibility(
                      visible: true, 
                      child: Row(
                        children: [
                          const Expanded(child: Text( Database: )),
                          Expanded(
                            child: TextField(
                              controller: dbController,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                  Expanded(
                    flex: 2,
                    child: Visibility(
                      visible: true, 
                      child: Row(
                        children: [
                          const Expanded(child: Text( Port: )),
                          Expanded(
                            child: TextField(
                              controller: portController,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                 //...

Answer 1

您有一个单一清单项目,有两个服务器。在这种情况下,

  String? selectedServer;

  final TextEditingController serverIPController = TextEditingController();
  void onServerChanged(String? value) {
    setState(() {
      selectedServer = value; 
                                /// having single item on the list, so index is 0
      serverIPController.text = serverList[0][selectedServer]?[ Server IP ] ?? "";
    });
  }

Row(
  children: [
    Text( Server ),
    Expanded(
      child: DropdownButton<String>(
        value: selectedServer,
        hint: const Text( Select Server ),
        items: serverList[0].keys.map((String value) {
          return DropdownMenuItem<String>(
            value: value,
            child: Text(value),
          );
        }).toList(),
        onChanged: onServerChanged,
      ),
    ),
  ],
),
Row(
  children: [
    const Expanded(child: Text( Server IP: )),
    Expanded(child: TextField(controller: serverIPController)),
  ],
),

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