hibernate

问题 Why does JPA OneToOne (or even OneToMany for that matter) have its orphanRemoval default to false . I mean, wouldn't it be better to force the remove operation to entities that have been removed from the relationship and to cascade the remove operation to those entities by default & have the user make the choice to not do it explicitly? Would the current behavior of the default being false not result in orphan entries (that might potentially become zombie records) that might lead to bloat of

问题 Why does JPA OneToOne (or even OneToMany for that matter) have its orphanRemoval default to false . I mean, wouldn't it be better to force the remove operation to entities that have been removed from the relationship and to cascade the remove operation to those entities by default & have the user make the choice to not do it explicitly? Would the current behavior of the default being false not result in orphan entries (that might potentially become zombie records) that might lead to bloat of

问题 I am facing a common error with Hibernate sessions : javax.persistence.TransactionRequiredException: Executing an update/delete query. I found a solution, make my test class extends AbstractTransactionalJUnit4SpringContextTests but I don't understand why is it necessary. I try to set junit (4.11 version) tests on my project. My test class : _ @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = { "classpath:config/ioc/application-context-spring-test.xml" })

问题 I am facing a common error with Hibernate sessions : javax.persistence.TransactionRequiredException: Executing an update/delete query. I found a solution, make my test class extends AbstractTransactionalJUnit4SpringContextTests but I don't understand why is it necessary. I try to set junit (4.11 version) tests on my project. My test class : _ @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = { "classpath:config/ioc/application-context-spring-test.xml" })

问题 I am facing a common error with Hibernate sessions : javax.persistence.TransactionRequiredException: Executing an update/delete query. I found a solution, make my test class extends AbstractTransactionalJUnit4SpringContextTests but I don't understand why is it necessary. I try to set junit (4.11 version) tests on my project. My test class : _ @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = { "classpath:config/ioc/application-context-spring-test.xml" })

问题 I wanted to get records of Patient (POJO class) who's contact number is not null. So, I referred this post. In the answer two ways are specified SELECT * FROM table WHERE YourColumn IS NOT NULL; SELECT * FROM table WHERE NOT (YourColumn <=> NULL); From above I wrote below hql which runs successfully from Patient p where p.contactNo is not null But, for 2nd type of hql from Patient p where not (p.contactNo <=> null) throws Exception org.hibernate.hql.internal.ast.QuerySyntaxException:

问题 How to find length of embedded nested array in mongodb? For example, I have the below collection in my mongoDB. The loc field contains coordinates field which is an array and again it contains another array which is in 0th index. How can I find length of loc.corrdinates[0] ? I tried to do this with using aggregation pipeline but it gives syntax error: db.atolldata.aggregate([ {$project:{_id:0, fileName:1, sizeOfArray:{$size:"$loc.coordinates[0]"}}}]); . Here is my collection db.mydb.findOne()

问题 How to find length of embedded nested array in mongodb? For example, I have the below collection in my mongoDB. The loc field contains coordinates field which is an array and again it contains another array which is in 0th index. How can I find length of loc.corrdinates[0] ? I tried to do this with using aggregation pipeline but it gives syntax error: db.atolldata.aggregate([ {$project:{_id:0, fileName:1, sizeOfArray:{$size:"$loc.coordinates[0]"}}}]); . Here is my collection db.mydb.findOne()

问题 I try to follow the @OneToOne bidrectional example from documetation but I always have a null reference in the PhoneDetails phone_id colum, and obtein a Phone with null details when do a get. I follow the documentation creating Phone and PhoneDetails Classes as is say. But because the documentation don't specify how to test and I need to develop an Spring Boot app, I create one to test and maybe, in any step of this I have the error. Here are my steps, and the code I update to github hoping

问题 There are two entities with relation @ManyToOne and @OneToMany (Categories and Products). When I enabeling (cascade=CascadeType.ALL) one record in Products pulls for deleting one Category, and that is BAD. What must be do for this entities that result is only deleting occurs in one place(Table) without cascade(related) delete for another reference??? I am using Spring 5.1.5 (not Spring Boot) Thank you! SPRING 5 / TOMCAT 9 / JACKSON-DATABIND / spring-data-jpa 2.1.5 / persistence-api 1.0.2 /