如果有人可以帮助我解决这个问题。所以我可以使用下面的代码获取并插入下拉按钮。如果我选择第一个下拉列表,则列表会相应地显示第二个下拉列表,如果我选择另一个值,则列表会更改。但是,当我在列表之间进行多次选择时,它会给我一个错误,例如:
引发了另一个异常:应该只有一个具有 [DropdownButton] 值的项目:Ointments。
检测到具有相同值的 0 个或 2 个或多个 [DropdownButton]。
我认为这是因为我正在调用按钮的 onChanged: 内的函数。任何帮助将非常感激。谢谢!
注意:我还在 initState 中只放置了 dynamicDropDownMainCategory() 函数。
//FIRST DROPDOWNBUTTON BELOW
//
child: DropdownButton<String>(
hint: Text('Select Category'),
icon: Icon(Icons.keyboard_arrow_down),
iconSize: 28,
isDense: true,
isExpanded: true ,
elevation: 16,
style: TextStyle(
color: Colors.black,
fontSize: 16.0,
),
value: categoryManualCurrent.isNotEmpty ? categoryManualCurrent : null,
onChanged: (String categoryValue) async {
// await dynamicDropDownMainCategory();
setState(() {
mainCategoryCurrent = categoryValue;
categoryManualCurrent = categoryValue;
});
print('THIS' + categoryManual.toString());
print('THAT' + subCategoryManual.toString());
await dynamicDropDownSubCategory();
},
items: categoryManual.toList()
.map((var value3) {
return DropdownMenuItem<String>(
value: value3,
child: Text(value3),
);
}).toList(),
),
)
],
),
//SECOND DROPDOWNBUTTON BELOW
//
child: DropdownButton<String>(
hint: Text('Select subCategory'),
icon: Icon(Icons.keyboard_arrow_down),
iconSize: 28,
isDense: true,
isExpanded: true ,
elevation: 16,
style: TextStyle(
color: Colors.black,
fontSize: 16.0,
),
value: subCategoryManualCurrent.isNotEmpty ? subCategoryManualCurrent : null,
onChanged: (String subCategoryValue) async {
//await dynamicDropDownMainCategory();
await dynamicDropDownSubCategory();
subCategoryCurrent = subCategoryValue;
setState(() {
subCategoryManualCurrent = subCategoryValue;
});
// await dynamicDropDownSubCategory();
},
items: subCategoryManual.toList()
.map((var value1) {
return DropdownMenuItem<String>(
value: value1,
child: Text(value1),
);
}).toList(),
),
),
]
),
//TWO functions im using to call the list data from firestore and insert into the //dropdownbutton
Future dynamicDropDownMainCategory() async{
await Firestore.instance
.collection('Products')
.document('Categories')
.get()
.then((snapshot) => {
categoryManual = (snapshot.data['mainCategory']),
}
);
}
Future dynamicDropDownSubCategory() async{
await Firestore.instance
.collection('Products')
.document('Categories')
.get()
.then((snapshot) => {
if (mainCategoryCurrent == categoryManualCurrent){
subCategoryManual = (snapshot.data['subCategory'+' '+mainCategoryCurrent]),
} else {
subCategoryManual = ['Error Getting Data'],
}
}
);
}