6，我正在使用一个下拉列表从数据库表中读取一列。我想要做的就是在该下拉列表上获取选定的值，并使用它创建一个新查询，并将其填充到新的下拉菜单中。
在阅读并查看了几个示例之后，我看到人们使用ajax，而其他人使用laravel HTTP请求（例如$request->get()），所以我不知道应该采取哪种方式，因为我对其中的任何一个都不熟悉，甚至什么时候尝试几次无法使其正常工作。
任何人都可以让我深入了解最佳/高效的方法吗？是否可以仅使用php或我缺少的laravel中的某些功能来做到这一点？
这是我的控制人：
public function selectsector() //this is the dropdown #1 that works fine
{
$sectors = DB::table('Sectors')->whereBetween('SectorID', [1, 10])->value('SectorID');
return view('besttradesview', ['sectors10' => $sectors]);
}
public function selectsubsector() //dropdown #2 not working
{
$subsectors = DB::table('Sectors')->where('parentid', $sectors)->get();
//this line is not working it does not recognize $sector variable
return view('besttradesview', ['subsectors42' => $subsectors]);
}
具有下拉菜单＃1：扇区和＃2：子扇区的视图
<form method="GET">
<div class="selectsector">
<Select class="selectsector" name = "sector">
@foreach($sectors10 as $sector)
<option>{{ $sector->SectorName }}</option>
@endforeach
</select>
<Select class="selectsubsector" name = "subsector">
@foreach($subsectors42 as $subsector)
<option>{{ $subsector->SectorName }}</option>
@endforeach
</select>
</form>
路线：
Route::get('kitysoftware/besttrades', 'SectorsController@selectsector');
Route::get('kitysoftware/besttrades', 'SectorsController@selectsubsector');
获取错误：未定义变量：扇区
答案 0 :(得分：3)
好吧，我设法使用json数据类型的javascript和ajax函数来做到这一点。我是JavaScript的新手，花了我一段时间，所以我花时间为新手发布详细信息。我们开始：
查看文件： 诀窍是使用html隐藏对象，该对象会在下拉菜单之前的这一行中捕获路由+前缀：
<input type="hidden" name="application_url" id="application_url" value="{{URL::to(Request::route()->getPrefix()) }}"/>
该对象的名称为“ application_url”，我们稍后将在javascript代码中使用该对象来完成路由所需的url。
名称为“ sectorSelect”的DropDown＃1：
<label class="selectsector">Sector:</label>
<Select class="selectsector" id="sectorSelect" name="sectorSelect" >
<option value=""> -- Please select sector --</option>
@foreach ($sectors10 as $sector)
<option value="{{ $sector->SectorID }}">{{ $sector->SectorName }}</option>
@endforeach
</select>
DropDown＃2，名称为：“ SubsectorSelect”
<label class="selectsector">SubSector:</label>
<Select class="selectsector" id="subSectorSelect" name="subSectorSelect">
<option value=""> -- Select an option --</option> // you don't have to do nothing here since this will be populated it from a query depending on the dropdown#1 selected value
</select>
现在在web.php路由文件中：
Route::get('kitysoftware/sectors/subsectors/{id}', 'SectorsController@selectsubsector');
我们正在创建一个带有{id}参数的路由。这将是下拉菜单1中的选定值。然后，在Sectorscontroller中调用“ selectsubsector”方法。
控制器： 第一个下拉查询：
public function selectsector()
{
$sectors = DB::table('Sectors')->select('SectorName', 'SectorID')-
>whereBetween('SectorID', [1, 10])->get();
return view('besttradesview', ['sectors10' => $sectors]);
第二个下拉查询（selectsubsector方法）：
public function selectsubsector($sectorId)
{
$subsectors = DB::table('Sectors')->select('SectorName', 'SectorID')->where('parentid', $sectorId)->get();
return response()->json($subsectors); //this line it's important since we are sending a json data variable that we are gonna use again in the last part of the view.
}
视图文件的最后部分 javaScript + ajax函数
<script type="text/javascript">
$('#sectorSelect').change(function () { //we watch and execute the next lines when any value from the dropdown#1 is selected
var id = $(this).val(); //we get the selected value on dropdown#1 and store it on id variable
var url = $('#application_url').val(); //we get the url from our hidden element that we used in first line of our view file, and store it on url variable
//here comes the ajax function part
$.ajax({
url: url + "/kitysoftware/sectors/subsectors/" + id, //we use the same url we used in our route file and we are adding the id variable which have the selected value in dropdown#1
dataType: "json", //we specify that we are going to use json type of data. That's where we sent our query result (from our controller)
success: function (data) { //*on my understanding using json datatype means that the variable "data" gets the value and that's why we use it to tell what to do since here.*
//and this final part is where we use the dropdown#1 value and we set the values for the dropdown#2 just adding the variables that we got from our query (in controllert) through "data" variable.
$('#subSectorSelect').empty();
$.each(data, function (key, value) {
$('#subSectorSelect').append('<option value="' + key.SectorID + '">' + value.SectorName + '</option>');
});
}
});
});
</script>
希望它有助于解决方案和解释。我也很高兴获得一些反馈。
答案 1 :(得分：1)
我希望这是您的要求：
<Select class="selectsector" onChange="getSelectorValue( this, '#selector2' )" id="selector1" name="sector">
@foreach($sectors10 as $sector)
<option>{{ $sector->SectorName }}</option>
@endforeach
</select>
<Select class="selectsubsector" onChange="getSelectorValue( this, '#selector1' )" name = "subsector" id="selector2" >
@foreach($sectors10 as $sector)
<option>{{ $sector->SectorName }}</option>
@endforeach
</select>
添加脚本使其生效：
<script type="text/javascript">
function getSelectorValue( selectorObj, selector ){
document.querySelector( selector ).value = selectorObj.value;
}
</script>
答案 2 :(得分：0)
控制器
aws ecr get-login-password | docker login --username AWS --password-stdin MY-REGISTRY-URL
路线
public function selectsector()
{
$sectors = Sector::get();
return view('besttradesview', compact('sectors'));
}
public function selectsubsector($sectors)
{
$subsectors = Sectors::where('parentid', $sectors)->get();
if (empty($subsectors)) {
$html = '';
$html = '<option value="">There has no Value</option>';
} else {
$html = '';
foreach ($subsectors as $subsector) {
$html .= '<option value="'.$subsector->id.'">'.$subsector->subsector.'</option>';
}
}
return response()->json(['html' => $html]);
}
ajax
Route::get('/get-selector/{id}', 'Inventory\selectorController@selectsubsector')->name('get.selector');