I have in a Spring Repo something like this:
findTop10ItemsByCategIdInOrderByInsertDateDesc(List ids)
I want the first 10 items where category id in list of ids ordered by insert date.
Another similar query:
findTop10ItemsByDomainIdAndCategIdInOrderByInsertDateDesc(List ids, #Param Integer domainId)
Here I want that the domain id is equal to the given param and the categId to be in given list.
I managed to resolve it using #Query but I wonder if there is an one liner for the above queries.
thanks
EDIT
The top works fine. Initially I had findTop10ItemsByDomainIdAndCategIdOrderByInsertDateDesc. Now I want the results from a list of category ids. That's the new requirement.
SECOND EDIT
My query works for find the set o results where domain id is equal to a given param and categ id is contained in a given list. BUT I found out that HQL doesn't support a setMaxResult kind of thing as top or limit.
#Query("select i from Items i where i.domainId = :domainId and i.categId in :categoryIds order by i.insertDate desc")
The params for this method were (#Param("domainid") Integer domainid,List<Integer> categoryIds) but it seams that I'm alowed to use either #Param annotation to each parameter or no #Param at all ( except for Pageable return; not my case )
I still don't know how to achieve this think:
extract top n elements where field a eq to param, field b in set of param, ordered by another field.
ps: sorry for tags but there is no spring-crudrepository :)
The method to resolve your problem is:
List<MyClass> findTop10ByDomainIdAndCategIdInOrderByInsertDateDesc(Long domainId, List<Long> ids);
Top10 limits the results to first 10.
ByDomainId limits results to those that have passed domainId.
And adds another constraint.
CategIdIn limits results to those entries that have categId in the passed List.
OrderByInsertDateDesc orders results descending by insert date before limiting to TOP10.
I have tested this query on the following example:
List<User> findTop10ByEmailAndPropInOrderByIdDesc(String email, List<Long> props);
Where User is:
private Long id;
private String username;
private String password;
private String email;
private Long prop;
Currently I would recommend using LocalDate or LocalDateTime for storing dates using Spring Data JPA.
Related
So I have a table of tags. Tag has an id and a name.
As a first step I wanted to sort all the IDs by descending order
List<Tag> findAllByOrderByIdDesc()
Next I wanted just to get first three tags and got it done by doing
List<Tag> findTop3ByOrderByIdDesc()
Now I want to get all tags in descending order from position x until position x+3 but I can't seem to find or figure out what to do here.
You can pass Pageable parameter.
Example:
List<Tag> findTop3ByOrderByIdDesc(Pageable page);
In the Pageable parameter you need to pass page number and offset.
Consider if you want to get values range from id 20 to 30.
PageRequest.of(2,10);
pass this as your Pageable parameter.
Pageable is a good idea but you have to use PagingAndSortingRepository or JpaRepository, not CrudRepository.
I came to a problem where I need to put ordering by multiplication of two columns of entity, for the sake of imagination entity is:
#Entity
public class Entity {
#Column(name="amount")
private BigDecimal amount;
#Column(name="unitPprice")
private BigDecimal unitPrice;
.
.
.
many more columns
}
My repo interface implements JpaRepository and QuerydslPredicateExecutor,
but I am struggling to find a way to order my data by "amount*unitPrice",
as I can't find a way to put it into
PageRequest (new Sort.Order(ASC, "amount * unitPrice"))
without having PropertyReferenceException: No property amount * unitPrice... thrown.
I can't user named query, as my query takes quite massive filter based on user inputs (can't put where clause into query, because if user hasn't selected any value, where clause can't just be in query).
To make it simple. I need something like findAll(Predicate, Pageable), but I need to force that query to order itself by "amount * unitPrice", but also have my Preditate (filter) and Pageable (offset, limit, other sortings) untouched.
Spring Sort can be used only for sorting by properties, not by expressions.
But you can create a unique sort in a Predicate, so you can add this sort-predicate to your other one before you call the findAll method.
I have domain object Person with date fields:
public class Person {
#Id
private Long id;
private Date date
Build example like this:
Person person = new Person();
person.setSomeOtherFields("some fields");
Example<Person> example = Example.of(person);
How i can create example query with date range (search entity contains date greater or equal from some date and less or equal some another date)?
The Spring Data JPA query-by-example technique uses Examples and ExampleMatchers to convert entity instances into the underlying query. The current official documentation clarifies that only exact matching is available for non-string attributes. Since your requirement involves a java.util.Date field, you can only have exact matching with the query-by-example technique.
You could write your own ExampleMatcher that returns query clauses according to your needs.
I've modified an existing RESTful/JDBC application i have to work with new features in Spring 4... specifically the JpaRepository. It will:
1) Retrieve a list of transactions for a specified date. This works fine
2) Retrieve a count of transactions by type for a specified date. This is not working as expected.
The queries are setup similarly, but the actual return types are very different.
I have POJOs for each query
My transactions JPA respository looks like:
public interface MyTransactionsRepository extends JpaRepository<MyTransactions, Long>
//My query works like a charm.
#Query( value = "SELECT * from ACTIVITI_TMP.BATCH_TABLE WHERE TO_CHAR(last_action, 'YYYY-MM-DD') = ?1", nativeQuery = true )
List< MyTransactions > findAllBy_ToChar_LastAction( String lastActionDateString );
This returns a list of MyTransactions objects as expected. Debugging, i see the returned object as ArrayList. Looking inside the elementData, I see that each object is, as expected, a MyTransactions object.
My second repository/query is where i'm having troubles.
public interface MyCountsRepository extends JpaRepository<MyCounts, Long>
#Query( value = "SELECT send_method, COUNT(*) AS counter FROM ACTIVITI_TMP.BATCH_TABLE WHERE TO_CHAR(last_action, 'YYYY-MM-DD') = ?1 GROUP BY send_method ORDER BY send_method", nativeQuery = true )
List<MyCounts> countBy_ToChar_LastAction( String lastActionDateString );
This DOES NOT return List as expected.
The object that holds the returned data was originally defined as List, but when I inspect this object in Eclipse, I see instead that it is holding an ArrayList. Drilling down to the elementData, each object is actually an Object[2]... NOT a MyCounts object.
I've modified the MyCountsRepository query as follows
ArrayList<Object[]> countBy_ToChar_LastAction( String lastActionDateString );
Then, inside my controller class, I create a MyCounts object for each element in List and then return List
This works, but... I don't understand why i have to go thru all this?
I can query a view as easily as a table.
Why doesn't JPA/Hibernate treat this as a simple 2 column table? send_method varchar(x) and count (int or long)
I know there are issues or nuances for how JPA treats queries with counts in them, but i've not seen anything like this referenced.
Many thanks for any help you can provide in clarifying this issue.
Anthony
That is the expected behaviour when you're doing a "group by". It will not map to a specific entity. Only way this might work is if you had a view in your database that summarized the data by send_method and you could map an entity to it.
I Have a list of string where i want to find particular value and return.
If i just want to search i can use Hashset instead of list
HashSet<string> data = new HashSet<string>();
bool contains = data.Contains("lokendra"); //
But for list i am using Find because i want to return the value also from list.
I found this methos is time consuming. The method where this code resides is hit more than 1000 times and the size of list is appx 20000 to 25000.This method takes time.Is there any other way i can make search faster.
List<Employee> employeeData= new List<Employee>();
var result = employeeData.Find(element=>element.name=="lokendra")
Do we have any linq or any other approach which makes retrievel of data faster from search.
Please help.
public struct Employee
{
public string role;
public string id;
public int salary;
public string name;
public string address;
}
I have the list of this structure and if the name property matches the value "lokendra".then i want to retrun the whole object.Consider list as the employee data.
I want to know the way we have Hashset to get faster search is there anyway we can search data and return fast other than find.
It sounds like what you actually want is a Dictionary<string, Employee>. Build that once, and you can query it efficiently many times. You can build it from a list of employees easily:
var employeesByName = employees.ToDictionary(e => e.Name);
...
var employee;
if (employeesByName.TryGetValue(name, out employee))
{
// Yay, found the employee
}
else
{
// Nope, no employee with that name
}
EDIT: Now I've seen your edit... please don't create struct types like this. You almost certainly want a class instead, and one with properties rather than public fields...
You can try with employeeData.FirstOrDefault(e => e == "lokendra"), but it still needs to iterate over collection, so will have performance list Find method.
If your list content is set only once and then you're searching it again and again you should consider implementing your own solution:
sort list before first search
use binary search (which would be O(log n) instead of O(n) for standard Find and Where)