背景：当option特别多时，一般的下拉框选择起来就有点力不从心了，所以使用multiselect是个很好的选择，可以通过输入文字来选择选项很方便，但是有一个需要下拉框联动，网上找了半天才找到解决方法，在此分享一下

1、先引入 <script src="~/Assets/js/bootstrap-multiselect.min.js"></script>

    <link href="~/Assets/css/bootstrap-multiselect.css" rel="stylesheet" />

然后全局定义

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  function RegSelect() {
            $('.multiselect').multiselect({
                buttonClass: 'btn btn-white ',
                enableFiltering: true,
                enableHTML: true,
                includeSelectAllOption: true,
                selectAllText: '全选',
                allSelectedText: '全部选中',
                nonSelectedText: '请选择',
                nSelectedText: '个被选中',
                templates: {
                    button: '<button type="button" class="multiselect dropdown-toggle" data-toggle="dropdown"><span class="multiselect-selected-text"></span> &nbsp;<b class="fa fa-caret-down"></b></button>',
                    ul: '<ul class="multiselect-container dropdown-menu"></ul>',
                    filter: '<li class="multiselect-item filter"><div class="input-group"><span class="input-group-addon"><i class="fa fa-search"></i></span><input class="form-control multiselect-search" type="text"></div></li>',
                    filterClearBtn: '<span class="input-group-btn"><button class="btn btn-default btn-white btn-grey multiselect-clear-filter" type="button"><i class="fa fa-times-circle red2"></i></button></span>',
                    li: '<li><a tabindex="0"><label></label></a></li>',
                    divider: '<li class="multiselect-item divider"></li>',
                    liGroup: '<li class="multiselect-item multiselect-group"><label></label></li>'
                }


            });
        }
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只需要在页面加载时RegSelect();（只能调用一次，不然会出现问题）就可以了

2、两个下拉框

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 <div class="form-group">
                    <label for="RepairOrg" class="col-sm-3 control-label">维修单位</label>
                    <div class="col-sm-9">
                        @Html.DropDownList("RepairOrgUID", ViewBag.OrgList as List<SelectListItem>, "请选择", new { @class = "form-control multiselect", onchange = "OrgChange(this)", id = "RepairOrg" })
                    </div>

                </div>

                <div class="form-group">
                    <label for="RepairContact" class="col-sm-3 control-label">维修人</label>
                    <div class="col-sm-9">
                        @Html.DropDownList("RepairContactUID", ViewBag.ContactList as List<SelectListItem>, "请选择", new { @class = "form-control multiselect", id = "RepairContact" })
                    </div>



                </div>
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3、js代码

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 function OrgChange(obj, patientID) {
            var RepairOrg = $(obj).val();
            $.post("/TerminalManage/GetContactByOrg", { RepairOrg: RepairOrg }, function (data) {          
                var newCitys = new Array();
                var obj = new Object();
                obj = {
                    label: "请选择",
                    value: ""
                };
                newCitys.push(obj);
                for (var i = 0; i < data.length; i++) {

                    obj = {
                        label: data[i].Text,
                        value: data[i].Value
                    };
                    newCitys.push(obj);
                    
                }

                $("#RepairContact").multiselect('dataprovider', newCitys);
                $('#RepairContact').multiselect('refresh');
            });
        }
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