Element-ui el-cascader不觸發prop?

html代碼：

    <el-form label-position="right" label-width="100px" :model="formInline" style="width: 380px;" :rules="rules" ref="form">
    <el-form-item label="所屬部門" prop="selectedId">
          <el-cascader
            :options="treeData"
            expand-trigger="hover"
            filterable
            :show-all-levels="false"
            v-model="formInline.selectedId"
            :props="defaultProps"
            change-on-select
            @change="handleChange">
          </el-cascader>
        </el-form-item>
      </el-form>

驗證代碼：

rules: {
        selectedId: [{
          type: 'array',
          required: true,
          message: '請選擇部門',
          trigger: 'change'
        }]
       }

注意：代碼中強調的地方。必須一致。 驗證： type: 'array'