Laravel 5.6:从下拉列表中获取选定的值以在另一个中使用它 [英] Laravel 5.6: Get selected value from a dropdown to use it in another

问题描述

6，我正在使用一个下拉列表从数据库表中读取一列.我想要的只是在该下拉列表上获取选定的值，然后使用它创建一个新查询，并将其填充到新的下拉菜单中.

6, I'm using a dropdown to read a column from a database table. All I want is to get the selected value on that dropdown and use it to create a new query that will be populated in a new drop-down.

阅读并看了几个示例后，我看到人们使用ajax，而其他人使用laravel HTTP请求(如$request->get())，所以我不知道该采取哪种方式，因为我对其中的任何一个都不熟悉，甚至在尝试多个时代使它无法正常工作.

After reading and see several examples I see people using ajax and other people using laravel HTTP request like $request->get() so i don't know which way to take since I'm not familiar with any of those and even when trying several times can't get it to work.

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?

Can anyone give me an insight into the best/efficient way to do it? Is it possible to do it only using php or some feature in laravel that I'm missing?

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

View with dropdow #1: sector and #2: subsector

<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

Getting error: Undefined variable: sectors

推荐答案

好，我设法使用具有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:

Ok, i managed to do it using javascript and ajax function with json datatype. I'm new at JavaScript and it took me a while so i'm taking the time to publish the details for the newcomers. Here we go:

查看文件: 诀窍是使用html隐藏对象，该对象会在下拉列表之前捕获此行的路由+前缀:

The View file: The trick is to use a html hidden object that captures a route + prefix like in this line before the dropdowns:

 <input type="hidden" name="application_url" id="application_url" value="{{URL::to(Request::route()->getPrefix()) }}"/>

此对象的名称为"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:

The name of this object is "application_url" which we'll be using later in the javascript code to complete the url that the routes needs.
DropDown#1 with name "sectorSelect":

<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"

DropDown #2 with name: "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.然后我们在Sectorscontroller中调用"selectsubsector"方法.

We are creating a route with an {id} parameter. This will be the selected value in dropdown #1. Then we call the "selectsubsector" method in the Sectorscontroller.

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):

Second Dropdown query (selectsubsector method):

   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

Final part of the view file The javaScript + ajax function

<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>

希望它对解决方案和解释有所帮助.我也很高兴获得一些反馈.

Hope it helps the solution and the explanations. I'm happy to get some feedback as well.

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