使用Laravel Route进行Ajax删除时出现500错误

Question

我花了将近6个小时找到解决方案来解决这个问题，但是失败了

$(document).ready(function(){

var url = "api/departments";

//display modal form for department editing
$('.open-modal').click(function(){
    var department_id = $(this).val();

    $.get(url + '/' + department_id, function (data) {
        //success data
        console.log(data);
        $('#department_id').val(data.id);
        $('#department').val(data.department);
        $('#btn-save').val("update");

        $('#myModal').modal('show');
    }) 
});

//display modal form for creating new department
$('#btn-add').click(function(){
    $('#btn-save').val("add");
    $('#frmDepartments').trigger("reset");
    $('#myModal').modal('show');
});

//delete department and remove it from list
$('.delete-department').click(function(){
    var department_id = $(this).val();

    $.ajax({

        type: "DELETE",
        url: url + '/' + department_id,
        success: function (data) {
            console.log(data);

            $("#department" + department_id).remove();
        },
        error: function (data) {
            console.log('Error:', data);
        }
    });
});

//create new department / update existing department
$("#btn-save").click(function (e) {
    $.ajaxSetup({
        headers: {
            'X-CSRF-TOKEN': $('meta[name="_token"]').attr('content')
        }
    })

    e.preventDefault(); 

    var formData = {
        department: $('#department').val(),
        //description: $('#description').val(),
    }

    //used to determine the http verb to use [add=POST], [update=PUT]
    var state = $('#btn-save').val();

    var type = "POST"; //for creating new resource
    var department_id = $('#department_id').val();;
    var my_url = url;

    if (state == "update"){
        type = "PUT"; //for updating existing resource
        my_url += '/' + department_id;
    }

    console.log(formData);

    $.ajax({

        type: type,
        url: my_url,
        data: formData,
        dataType: 'json',
        success: function (data) {
            console.log(data);

            var department = '<tr id="department' + data.id + '"><td>' + data.id + '</td><td>' + data.task + '</td><td>' + data.created_at + '</td>';
            department += '<td><button class="btn btn-warning btn-xs btn-detail open-modal" value="' + data.id + '">Edit</button>';
            department += '<button class="btn btn-danger btn-xs btn-delete delete-department" value="' + data.id + '">Delete</button></td></tr>';

            if (state == "add"){ //if user added a new record
                $('#departments-list').append(department);
            }else{ //if user updated an existing record

                $("#department" + department_id).replaceWith( department );
            }

            $('#frmDepartments').trigger("reset");

            $('#myModal').modal('hide')
        },
        error: function (data) {
            console.log('Error:', data);
        }
    });
});
});

我有这条路线

//departments
Route::resource('/departments', 'DepartmentController@index');


Route::get('/api/departments/{department_id?}',function($department_id){
$department = App\Models\Department::find($department_id);

return Response::json($department);
});

Route::post('/api/departments',function(Request $request){
$department = App\Models\Department::create($request->all());

return Response::json($department);
});

Route::put('/api/departments/{department_id?}',function(Request   $request,$department_id){
$department = App\Models\Department::find($department_id);

$department->department = $request->department;

$department->save();

return Response::json($department);
});

Route::delete('/api/departments/{department_id?}',function($department_id){
$department = App\Models\Department::destroy($department_id);

return Response::json($department);
});

删除或错误

  

删除http://localhost:8089/api/departments/1 500（内部服务器）

保存编辑

  

PUT http://localhost:8089/api/departments/1 500（内部服务器错误）

知道如何解决这个问题吗？

在浏览器中直接访问路径将显示json数据

 my_url/api/departments/1


 {"id":1,"department":"Dolorum at consectetur amet ut eligendi quia in earum. Magnam nihil ut voluptatem quisquam cum ad. Magni quo qui et molestiae.","created_by":"Dr. Filiberto Larson DDS","updated_by":"Anabelle Kling","created_at":"2016-05-16 05:47:13","updated_at":"2016-05-16 05:47:13"}