I am using Hibernate & Spring In my project. I need to access already existing table values from DB using hibernate.
I just have an entity class & I use Constructor injection here.
I am Using Hibernate & spring in same file.
Hibernate allows to generate beans and mapping configuration out of existing databases. This is called `Reverse Engineering'.
You can find the documentation here:
http://docs.jboss.org/tools/latest/en/hibernatetools/html/reverseengineering.html
Related
Is it possible to stop spring JPA from generating table for a specific entity ?
Reason:
I want to put all my native sql queries into a separate object using #NamedNativeQuery. But #NameNativeQuery requires #Entity annotation. Due to that, and unwanted table is generated automatically.
Is it possible to add an #Entity, and stop at the same time spring boot to generate table for that entity ?
P.S: I don't want to put the queries into the parent #entity, because there are too many queries. I want to have a good model structure.
My settings :
spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto=none
Spring Boot version : 2.3.3
Hibernate version : 5.6.7.Final
Have a situation where I need to use single JPA Entity class for different databases.
I have used #Nationalized annotation on fields to support I18N. I need this #Nationalized annotation applicable only when I use oracle as my database. If I use same code for other databases it should not be consider(eg: derby)
is there any mechanism to achieve this in hibernate
I am trying to validate database schema before running any queries using jdbc template. So is there any way to identify schema changes before making any queries in spring programmatically?? Currently I am using spring boot 2 and hibernate 5.
Add this to the configuration file.
hibernate.hbm2ddl.auto=validate
If the value is validated then hibernate only validates the table structure- whether the table and columns have existed or not. If the table doesn’t exist then hibernate throws an exception.
Validate is the default value for hbm2ddl.auto.
I working on a project which uses Spring boot , Spring Data JPA and postgres .There is a problem that can't solve .
When my application start up ,The database not ready yet . It need to add to application at runtime . But I also want to initialize a database using JPA.
just like spring.jpa.hibernate.ddl-auto：create-drop，Unfortunately Initialize a database using JPA will happen at application startup.
My question is that how to delay spring data jpa DDL generation. now we can't add a datasource at application runtime.
I am searching for a long time on net. But no use. The AbstractRoutingDataSource may be not suit for us, because we don't have a datasource at begin .
Please help or try to give some ideas how to achieve this
Thanks in advance
AbstractRoutingDataSource is not useful as it requires pre-configured datasources.
just check this stackoverflow question, it shows how you can add/remove datasources at runtime. While it doesn't support hibernate's delayed ddl creation but you can create database tables in runtime datasources using schema.sql and inserts some constants using data.sql.
I have a spring boot application using spring jdbc template for DAO layer connecting to Oracle DB. The DB username is different than the schema on which the queries will be run. Hence when the queries are run it needs to run using a different schema and I do not want to prefix the hardcoded value for the schema(For ex select * from user1.table.....)
I researched a bit and couldn't find a simple and straight way to do that.
For ex if I were using JPA I could have simply configured the property spring.jpa.properties.hibernate.default_schema=<schema name> but couldn't find an equivalent way of configuring the same when using spring jdbc
I ran into a similar problem and didn't find an ideal way to do it. I ended up setting the schema in SQL when the app loaded. At least I was able to reuse spring.jpa.properties.hibernate.default_schema, which I already had set for the JPA default schema.
final String schemaName = jpaProperties.getProperties().get("hibernate.default_schema");
jdbcTemplate.execute("SET SCHEMA '" + schemaName + "'");
This clearly isn't ideal, but it is better than defining your schema in multiple places.
(Note: I autowired both the JpaProperties and JdbcTemplate.)
You need to use the Oracle JDBC Driver.
A good example can be found in this mykong article:
# Oracle settings
spring.datasource.url=jdbc:oracle:thin:#localhost:1521:xe
spring.datasource.username=system
spring.datasource.password=password
spring.datasource.driver-class-oracle.jdbc.driver.OracleDriver