如何使用FormBuilder FormBuilderChoiceChip FormBuilderChipOption Map(数值头像)

Question

我正在尝试使用 Map(String,String) 来满足 FormBuilderChipOption。我尝试过的代码如下：

   options:
        languageOptionsMap((city,letter) => FormBuilderChipOption(
          value: Text(city),
          avatar: CircleAvatar(child: Text(letter)),
        )).toList(growable: false),
    
    The Map is as follows:
    
      Map<String,String> languageOptionsMap = {
        'English': 'E',
        'Mandarin': 'M',
        'Hindi': 'H',
        'Spanish': 'S',
        'Arabic': 'A',
        'French': 'F',
        'Swedish': 'S',
        'Danish': 'D',
      };

我收到如下编译时错误：

======== Exception caught by widgets library =======================================================
The following NoSuchMethodError was thrown building CompleteForm(dirty, state: _CompleteFormState#5d199):
'call'
Dynamic call of object has no instance method 'call'.
Receiver: Instance of 'IdentityMap<String, String>'
Arguments: [Instance of '(dynamic, dynamic) => FormBuilderChipOption<Text>']

The relevant error-causing widget was: 
  CompleteForm CompleteForm:file:///C:/Users/stefa/StudioProjects/appformbuilder/lib/main.dart:45:19

我期待获得 FormBuilderChipOption 的值和头像。

Answer 1

在 dart 中，你无法调用 Map （它不是函数或函数对象），因此你必须首先获取元素 ( .entries )，然后将它们映射 ( .map )只需要输入的函数，而不是（城市，字母））：

options: languageOptionsMap.entries.map((entry) => FormBuilderChipOption( value: Text(entry.key), avatar: CircleAvatar(child: Text(entry.value)), )).toList(growable: false),