Spring Data Mongo - 如何通过@DBRef字段的id进行查询 [英] Spring Data Mongo - How to query by @DBRef field's id
问题描述
我是Spring Data Mongo的新手,所以我必须做错事,因为我无法设法执行这么简单的查询。这是我的模特:
I am new to Spring Data Mongo so I must be doing something wrong because I can't manage to execute such a simple query. This is my model:
@Document(collection="brands")
public class Brand{
@Id
private int id;
private String name;
...
//getters-setters
}
@Document(collection="models")
public class Model{
@Id
private int id;
private String name;
@DBRef
private Brand brand;
...
//getters-setters
}
我想从一个品牌获得所有模型,所以我按如下方式实现DAO:
I would like to get all models from a brand, so I implement the DAO as follows:
@Repository
public interface IModelDAO extends MongoRepository<Model, Integer>{
@Query(value="{ 'brand.$id' : ?0 }")
public List<Model> findByBrandId(Integer id);
}
如果我在shell中执行这个mongodb查询它可以工作: db.modelss.find({'brand。$ id':1})
If I execute this mongodb query in the shell it works: db.modelss.find({ 'brand.$id' : 1 })
但是,Java应用程序抛出以下异常:
But, the Java application throws the following exception:
Caused by: java.lang.IllegalAccessError
at org.springframework.data.mapping.PropertyReferenceException.detectPotentialMatches(PropertyReferenceException.java:134)
显然它正在寻找Brand类中的字段$ id,因为它不存在它失败了。所以我将查询更改为以下内容,以便导航到id字段:
Apparently it is looking for a field $id in Brand class, and since it doesn't exist it fails. So I change the query to the following, so that it navigates to the id field:
@Query(value="{ 'brand.id' : ?0 }")
现在,它不会抛出异常,但它在DB中找不到任何内容。
Now, it doesn't throw an exception but it doesn't find anything in the DB.
调试MongoTemplate.executeFindMultiInternal()方法可以看到
Debugging the MongoTemplate.executeFindMultiInternal() method in can see that in
DBCursor cursor = null;
try {
cursor = collectionCallback.doInCollection(getAndPrepareCollection(getDb(), collectionName));
光标的查询是 query = {brand:134}
。所以它没有找到任何东西是有道理的。在调试期间将查询值更改为query = {brand。$ id:134}它可以正常工作。
cursor's query is query={ "brand" : 134}
. So it makes sense it doesn't find anything. Changing the query value during debugging to query={ "brand.$id" : 134} it works.
那么,为什么查询没有正确翻译?
So, why isn't the query correctly translated?
推荐答案
问题是由 @Id
int 强>类型。将其更改为整数解决了它:
The problem was caused by the @Id
int type. Changing it to Integer solved it:
@Document(collection="brands")
public class Brand{
@Id
private Integer id;
private String name;
...
//getters-setters
}
@Document(collection="models")
public class Model{
@Id
private Integer id;
private String name;
@DBRef
private Brand brand;
...
//getters-setters
}
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