问题

我有这段代码，但在运行时出现了如下错误...

**无法找到符号
  符号：   方法 groupBy(java.lang.String)
  位置： 接口 com.avaje.ebean.ExpressionList<models.ClusterResources>**

public static List<ClusterResources> getClusterLeaderByEmpId(int cluster_id) {
List<ClusterResources> clusterLeaders = Ebean.find(ClusterResources.class)
.where()
.eq("cluster_id", cluster_id)
.groupBy("cluster_leader")
.findList();
if (clusterLeaders == null)
clusterLeaders = new ArrayList<>();
return clusterLeaders;
}

<details>
<summary>英文:</summary>

&gt; I have this code but while running i m getting error like...

**cannot find symbol
  symbol:   method groupBy(java.lang.String)
  location: interface com.avaje.ebean.ExpressionList&lt;models.ClusterResources&gt;**

public static List<ClusterResources> getClusterLeaderByEmpId(int cluster_id) {
    List<ClusterResources> clusterLeaders = Ebean.find(ClusterResources.class)
            .where()
            .eq("cluster_id", cluster_id)
            .groupBy("cluster_leader")
            .findList();
        if (clusterLeaders == null)
            clusterLeaders = new ArrayList<>();
    return clusterLeaders;
}

</details>


# 答案1
**得分**: 0

没有看到你的模型 ClusterResources，有点难以知道你想要实现什么，但是 Ebean 通常会在需要时自动添加 "group by"，例如，如果你选择了需要分组的内容：

.select("cluster_leader, MAX(cluster_value)")

请查看以下链接：
[Ebean 聚合][1] 和 [Ebean 选择][2]。

  [1]: https://ebean.io/docs/query/aggregation
  [2]: https://ebean.io/docs/query/select

<details>
<summary>英文:</summary>

without seeing your model ClusterResources it&#39;s a bit hard to know what you want to achieve, but Ebean will generally add &quot;group by&quot; automatically when needed, e.g. if you select something that needs grouping:

    .select(&quot;cluster_leader, MAX(cluster_value)&quot;)

Check out these links:
[Ebean aggregation][1] and [Ebean select][2]


  [1]: https://ebean.io/docs/query/aggregation
  [2]: https://ebean.io/docs/query/select

</details>