Ant Design vue Modal 中Select组件下拉选项随页面滚动与Select框分离异常 解决办法

  <a-form-item>
                <a-select
                  v-decorator="['inst_id']"
                  placeholder="请选择研究中心"
                  :getPopupContainer="(triggerNode)=>{ return triggerNode.parentNode}" 
                  allowClear
                  showSearch
                  :filterOption="filterOption"
                  @change="inst_change"
                >
                  <a-select-option
                    v-for="item in inst_list"
                    :key="item.id"
                    :value="item.id"
                  >{{item.instname}}</a-select-option>
                </a-select>
              </a-form-item>

  <a-form-item>

                <a-select

                  v-decorator="['inst_id']"

                  placeholder="请选择研究中心"

                  :getPopupContainer="(triggerNode)=>{ return triggerNode.parentNode}" 

                  allowClear

                  showSearch

                  :filterOption="filterOption"

                  @change="inst_change"

                >

                  <a-select-option

                    v-for="item in inst_list"

                    :key="item.id"

                    :value="item.id"

                  >{{item.instname}}</a-select-option>

                </a-select>

              </a-form-item>