Flutter 带有颤振贴图的下拉菜单项
我想在此地图中填充两个下拉菜单项:Flutter 带有颤振贴图的下拉菜单项,flutter,dart,Flutter,Dart,我想在此地图中填充两个下拉菜单项: var jobs = { "departments": ["dep1", "dep2", "dep3"], "dep1": ["job1", "job2"], "dep2": ["job3", "job4"], "dep3":
var jobs = {
"departments": ["dep1", "dep2", "dep3"],
"dep1": ["job1", "job2"],
"dep2": ["job3", "job4"],
"dep3": ["job5", "job6"]
};
下拉按钮1(部门)
下拉按钮2(作业)
但当我从第二个菜单中选择任何内容并更改第一个菜单的值时,我得到了这个错误:
Assertion failed: file:///home/koha/flutter/packages/flutter/lib/src/material
/dropdown.dart:1473:15
items == null || items.isEmpty || value == null ||
items.where((DropdownMenuItem<T> item) {
return item.value == value;
}).length == 1
"There should be exactly one item with [DropdownButton]'s value: job1. \nEither zero or 2 or
more [DropdownMenuItem]s were detected with the same value"
断言失败:file:///home/koha/flutter/packages/flutter/lib/src/material
/下拉。省道:1473:15
items==null | | items.isEmpty | | value==null||
项目。其中((DropdownMenuItem项目){
返回项。值==值;
}).length==1
“应该只有一个项目具有[DropdownButton]的值:job1。\n既不是零,也不是2,或者
检测到更多具有相同值的[DropdownMenuItem]
您正在更改第二个下拉列表中的项目,但变量“chosenJob”具有旧项目列表中的值。更改'chosenDep'变量时,请清除'chosenJob'内容。您正在更改第二个下拉列表中的项目,但变量'chosenJob'具有旧项目列表中的值。更改'chosenDep'变量时,请清除'chosenJob'内容。如果更改第一个变量,则必须将第二个变量更改为默认值
比如说
DropdownButton(
hint: Text(hint1),
value: chosenDep,
items: jobs['departments']
.map((e) => DropdownMenuItem(child: Text(e), value: e,))
.toList(),
onChanged: (value){
setState({
isDepChosen= true;
chosenDep = value;
chosenJob = jobs[chosenDep].first;
});
)
如果更改第一个,则必须将第二个更改为默认值 比如说
DropdownButton(
hint: Text(hint1),
value: chosenDep,
items: jobs['departments']
.map((e) => DropdownMenuItem(child: Text(e), value: e,))
.toList(),
onChanged: (value){
setState({
isDepChosen= true;
chosenDep = value;
chosenJob = jobs[chosenDep].first;
});
)
DropdownButton(
hint: Text(hint1),
value: chosenDep,
items: jobs['departments']
.map((e) => DropdownMenuItem(child: Text(e), value: e,))
.toList(),
onChanged: (value){
setState({
isDepChosen= true;
chosenDep = value;
chosenJob = jobs[chosenDep].first;
});
)