Anyone used this following BatchInsert with mybatis: (the documentation is bit not clear for me interms of implementation)
https://mybatis.org/mybatis-dynamic-sql/docs/insert.html
Don't know where that insert() method is coming from (I dont think it is within mapper)
My requirememt is in here Using HashMap dynamically for parameter mapping in mybatis
Due to performance issues I am not able to use the solution mentioned there. So just checking this mybatis dynamic sql..
Related
I had seen somewhere that it was said that #NamedNativeQuery does not support dynamic sorting. What is the reason? Does NamedNativeQuery do anything special at all? It only maps the query defined in it to a method in the repository, in which case you can use used pagination and dynamic sorting. (Because if we directly use #Query(query="...",nativeQuery=true) on the method, we can use dynamic sorting without any problem.)
What is the difference between JPAQuery and JPAQueryFactory?
And, When to use which?
According to the querydsl reference documentation:
Both JPAQuery and HibernateQuery implement the JPQLQuery interface.
For the examples of this chapter the queries are created via a JPAQueryFactory instance. JPAQueryFactory should be the preferred
option to obtain JPAQuery instances.
But, I could not understand clearly.
Can anyone explain it briefly?
What matters is that Hibernates query language (HQL) is a superset of JPA's query language (JPQL). Hibernate also has a special method for result set transformation and being able to iterate over scrollable result sets without the need to keep a reference to all records in memory. In order to take advantage of this extra functionality, the HQLTemplates and the HibernateHandler have to be used. The first is responsible for serializing the additional types of expressions, the second for the integration with Hibernates Query implementation. The HibernateHandler is actually obtained from the HQLTemplates as well, so all that remains is specifying HQLTemplates.
And in fact: a JPAQuery instantiated with HQLTemplates.INSTANCE for the Templates variable, behaves the same as a HibernateQuery. FWIW, if you provide an EntityManager instance with the construction of your JPAQuery, then the appropriate implementation for Templates is deduced for your ORM vendor automatically.
All JPAQueryFactory really is, is a factory method that binds the EntityManager and Templates variables for newly instantiated JPAQueries. This eliminates the need to pass these as a variable individually for each instantiation of a JPAQuery.
There is no need to use the JPAQueryFactory, but it could make your code easier to read. Furthermore, a lot of code examples on the QueryDSL website utilize the query factory, so it might make it easier to use these examples as snippets in your own code.
I'm having issues trying to get MyBatis and Javers (with Spring) integrated and working. I've followed instructions at http://javers.org/documentation/spring-integration/ and gotten the Aspect setup, and annotated my entity class and registered it with Javers, and the MyBatis interface correctly annotated with #Repository and #JaversAuditable on the appropriate methods, but still haven't gotten it to work, even setting breakpoints in the Javers Aspect, but nothing triggers.
I've also gone about it the other way, using MyBatis plugin interceptor, as per http://www.mybatis.org/mybatis-3/configuration.html#plugins (then used http://www.mybatis.org/spring/xref-test/org/mybatis/spring/ExecutorInterceptor.html as a basic example for commits). However while it's triggering, it's not doing what I expected and is basically just an aspect around on the commit method, which takes a boolean rather than containing which entity(ies) are being commited which would let me pass them to Javers. I suppose I could add an interceptor on the update/insert MyBatis methods, and then stored that in a ThreadLocal or similar so that when commit/rollback was called I could pass it to Javers as necessary, but that's messy.
I've got no clue where to go from here, unless someone can see something I've missed with one of those 2 methods.
So in my confusion, I realized that since MyBatis generates the concrete object for the Mapper Interfaces, Spring never seems the creation of that object, simply has the final object registered as a Bean in the context. Thus, Javers never has a chance to process the Bean as it's created in order to do any proxying or what not as necessary.
So, silly me. So I ended up creating a Spring-Data #Repository layer that mostly just passes the call through to the Mapper. Although on updates I'm doing some extra bits which the DAO shim layer (as I'm calling it) works well for.
My question is that how to call a function in LINQ query? e.g
source.Where(x=> double.Parse(x.Col1)==3)
or
source.Where(x=> AnyUserFunction(x.Col1)==true)
Basically my requirement is to check weather Col1 is a numeric value or not, but I occasionally need to call my User Defined functions as well.
The problem is that your Linq to Entities provider doesn't know how to translate your custom methods to SQL. The solution proposed by #teovankot is the easy way to solve this problem, but if you want to work with Linq to Objects I suggest you use AsEnumerable extension method instead ToList because AsEnumerable does not execute the query until you consult the data, it preserves deferred execution, but be careful, try to don't use AsEnumerable or ToList on the entire DbSet because you'd retrieve all rows of that table affecting your application's performance.
Now if you only want to check weather Col1 is a numeric value or not, another solution could be using SqlFunctions.IsNumeric method which is translated into native SQL:
using System.Data.Entity.SqlServer;
//...
source.Where(x=> SqlFunctions.IsNumeric(x.Col1)==1);
You can find another set of functions you can also call in the DbFunctions static class.SqlFunctions are SQL Server specific, whereas DbFunctions aren't.
You can't call user defined functions easy in linq to sql.
But you can do it after you get all your data from DB to your server. Like this:
source.ToList().Where(x=> AnyUserFunction(x.Col1)==true)
Note ToList() call. this will get all your data from DB so you basically working with linq to objects where you can easy use your user defined fucntions.
How do I use the 'exists' keyword in Spring Data in a query method?
I would like to have a method like this:
public interface ProfileRepository extends JpaRepository<Profile, Long> {
boolean existsByAttribute(String attribute);
}
where Attribute is a field of the Profile.
A workaround would be to use a custom-implementation. But the appendix defines exists as keyword. Could someone give me an example how to use this keyword?
Documented keywords are intended to be used in combination with a property reference. Thus, the semantics of EXISTS in this case are that it checks whether the property exists. Note, that the part of the documentation is pulled it from Spring Data Commons and the keyword being listed there doesn't mean it's supported in Spring Data JPA (indicated in the first paragraph of the section you linked). Exists is not supported by Spring Data JPA as it only makes sense in MongoDB for example as there's a difference between a field not present entirely and the field available with a logically null value.
So what you're looking for seems to be around the (Is)Null keyword with the current limitation that it would return objects and you'd have to check the returned list for content. There's a ticket to add support for projections for derived query methods which you might wanna follow for further progress.