findById()找不到属性ID [英] findById() gives No property Id found
问题描述
我有三个实体. (在此示例中，我使用xxx作为占位符)
I have three entities. (I am using xxx as a place holder for this example)
我已经用
@Entity
@Table(name = "xxx")
public class xxx {
@Id
@Column(name = "xxx_id")
int xxx_id;
但是，我能够做到:
findById(int ...)仅适用于各自存储库中的一个实体.
当我尝试对其他两个实体执行此操作时，出现此问题:
findById(int ...) for only ONE of the entities in their respective Repository.
When I try to do that for the other two entities, I get this problem:
无效的派生查询！找不到类型xxx的属性ID！"
"Invalid derived query! No property id found for type xxx!"
我能够运行它并获得适当的结果.但是，为什么我对于两个实体却收到了这个错误，而另一个实体却没有?
I am able to run it and get the proper results. But why am I getting this error for two entities but not the other?
我完全按照相同的方式设置实体及其存储库.
唯一的区别是，在其存储库不返回任何错误的实体中，我将该实体与另一个其存储库发生故障的实体连接在一起，但是在@JoinColumns部分中使用了"mappedBy" .
I set up the entities and their repositories exactly the same way.
The ONLY difference is that in the entity whose repository does not return any errors, I am joining that entity with another entity whose repository fails, but I used "mappedBy" in the @JoinColumns section.
这与为什么一个人没有问题有关吗?
Could that have something to do with why that one has no problems?
推荐答案
findBy ...如何工作?
How findBy... works?
Entity:
private int clientid;
private String firstname;
private String lastname;
查询:
Query:
findBy<Name_as_per_entity>
findByClientid(int clientid);
findByFirstnameAndLastname(String firstname, String lastname)
解决方案
由于我们将下划线字符视为保留字符，因此我们 强烈建议您遵循以下标准Java命名约定(即， 而不是在属性名称中使用下划线，而是使用驼峰式大小写.)
Because we treat the underscore character as a reserved character, we strongly advise following standard Java naming conventions (that is, not using underscores in property names but using camel case instead).
下划线_ 是Spring数据查询派生中的 保留字符 ，可能允许手动描述属性路径
The underscore _ is a reserved character in Spring Data query derivation to potentially allow manual property path description.
坚持使用 camel-case 来表示成员变量名称和所有内容的Java命名约定.将按预期工作.
Stick to the Java naming conventions of using camel-case for member variable names and everything will work as expected.
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