table表格条件判断, 选中按钮置灰

 <el-button
            v-permission="['admin', 'buSrmCoopPo:close']"
            size="mini"
            type="primary"
            class="filter-item"
            plain
            :disabled="checkOpd()"
            @click="close()"
          >
            关闭
          </el-button>

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/*关闭开启检测*/
      checkOpd() {
        if (this.mainSelections.length == 0) {
          return true;
        } else {
          const obj = this.mainSelections[0];
          if (obj.billStatus == "7") {
            return false;
          } else {
            return true;
          }
        }
      },