I have a list of JPA entities , and I want to know automatically the order used to generate Database schema , for example :
if Entity A has an association with Entity B , so Table B must be created before Table A , ( I need to know this order for synchronization purposes)
When you start your application , hibernate has a behavior to check the existing schemas (weather or not they persist or not). If the schemas are missing you should see hibernate Logging meta data messages such as (Table Found *table name *) for each and every table. I think that is what you are looking for . It generates all metadata info every time it scans your entity like table found , table created, table not found.
Related
I am using Hibernate eveners to keep the audit data of several entities (Enity_History the audit table) and I use the default REVINFO table.
Is there a way to delete the audit data, that is older than 3 months from today, without using a native query?
Yeah, you should be able to use HQL for this. For every entity with #Audited a new entity is created with the name suffix _AUD. So you should be able to do delete from fully.qualified.name.to.Entity_AUD e where add_days(e.originalId.timestamp, 30*3) < CURRENT_TIMESTAMP
In my application i am using below property
spring.jpa.properties.hibernate.hbm2ddl.auto= validate
so does it validates schema like if manually i added one new column in my oracle table and not added this column in java entity .
so in this case will it give error on project startup ?
No, it's perfectly alright to have columns in a table that aren't mapped. An error would be a missing column or table that's mapped to an entity. Your database doesn't need to be identical to your mappings.
Do we still have to map All tables to Entity Class in a Spring Hibernate Project ?
I have couple Tables :
- Quote (Transaction)
- NextNumber
- Branch (Master)
e.g :
I want to create a numbering like 'QF18-4238/BHP.SI/ISD', this numbering will saved in Quote Table.
For some Reason:
The Number '4238' -> will also saved in NextNumber Table.
The '/BHP.SI/ISD' -> will lookup from Branch Table depending on whos LoggedIn.
If Login as **A** the result will **'/BHP.TMI/MM'**
else if **B** the result will **''/BHP.SI/ISD**
Is it possible to just create one Entity Class ?
please enlighten me
Database Model:
I am following https://www.javatpoint.com/crud-in-servlet
to create an CRUD application in servlets and mysql.
Each user inputs his information in a webpage and submit to the web server, which then invokes a servlet SaveServlet to save the information as a record in a database table. The database table however has an additional "id".
SaveServlet.java doesn't create an id for each record. So I was wondering how to create an id for each record?
Thanks.
If you are using jpa/hibernate then your entity must be having the #Id annotation on the record id field (you dont need to set it, it will be done automatically based on you Id generation mechanism defined in the entity class and database schema).
if you are using plain jdbc for persisting records then you need to check the database how primary key is defined. for oracle you can your sequence.nextvalue to set the primary key.
Question, am currently using hibernate and I was wondering if there was any way to get the value of a lazy loaded entities id without hitting the DB again? For example we currently have an entity called group that has a ManyToOne relationship with another entity Organization.
when we call a simple repository method
groupsRepository.findByUser(id) it returns a list of groups based on given user. The query looks like this
select
groups0_.PersonId as PersonId1_118_1_,
groups0_.GroupId as GroupId2_8_1_,
groups1_.GroupID as GroupID1_74_0_,
groups1_.CreatedAt as CreatedA2_74_0_,
groups1_.CreatedBy as CreatedB3_74_0_,
groups1_.Description as Descript4_74_0_,
groups1_.Name as Name5_74_0_,
groups1_.OrganizationID as Organiza9_74_0_,
groups1_.Role as Role6_74_0_,
groups1_.Status as Status10_74_0_,
groups1_.TouchedAt as TouchedA7_74_0_,
groups1_.TouchedBy as TouchedB8_74_0_
from
Groupsofpeople groups0_
inner join
groups groups1_
on groups0_.GroupId=groups1_.GroupID
where
groups0_.PersonId=?
Later on I need to see if the groups org is equal to another org which I do by comparing the OrganizaitonId's, a value that has already been fetched from the db. But every time I do this I have fetch the org from the db, is there anyway to prevent that so that the org attached to group will be prepopulated with it's id since it is already being fetched anyway? Or is this just a concession I have to make if I am using hibernate?