Element vue Select 下拉框默認

<el-form :inline="true" :model="formData">
        <el-form-item label="所屬倉庫">
          <el-select v-model="formData.storageName" placeholder="請選擇" class="w-200" @change="getData()">
            <el-option v-for="item in storageNames" :key="item.storage_Id" :label="item.storageName" :value="item.storage_Id">
            </el-option>
          </el-select>
        </el-form-item>
      </el-form>                                                              -------------------v-model="formData.storageName"  給這個model 賦值

     getStorageList() {

      const url = "/api/basicInfo/base/storage/getList";

      const params = {};

      var callback = res => {

        if (res.result) {

          this.storageNames = res.data;

          this.formData.storageName = res.data[0].storageName;

        }

      };

      this.common.ajax(url, params, callback);

    }