In redis-om-spring I can search all fields by simply adding a search method to the repository.
public interface ProductRepository extends RedisDocumentRepository<Product, String> {
Page<Product> search(String text, Pageable pageable);
}
When using the EntityStream, I can search on specific fields, but not across all fields.
var result = entityStream.of(Product.class)
.anyMatch(new StartsWithPredicate<>(Product$.UNIQUE_ID.getField(),"100790"))
#AllArgsConstructor
public class Product{
#Id
String uniqueId;
#Searchable
String field1;
#Searchable
String field2;
#Searchable
String fieldN;
}
repo.save(new Product("UA","searchForA1","searchForA2","searchForAN");
repo.save(new Product("UB","searchForB1","searchForB2","searchForBN");
repo.save(new Product("UC","searchForC1","searchForC2","searchForCN");
I need to search across all fields. Am I missing something in the EntityStream API or is this not possible?
Something that generates:
FT.SEARCH my-idx "thesearchTerm"
Yes, there is a filter method in the SearchStream interface that takes a free-form text String:
SearchStream<E> filter(String freeText);
See https://github.com/redis/redis-om-spring/blob/main/redis-om-spring/src/main/java/com/redis/om/spring/search/stream/SearchStream.java#L20
Related
I have a JSON value stored in SQL Server. I want to retrieve that JSON value and bind it to C# property (which is deserialized to desired entity). I want to know what would be the best practice to do that effectively? Right now, I'm doing like this:
Public class Employee
{
public int Id;
public string Name;
public int Age;
}
Public class EmployeeData
{
public string JsonEmployeeText {get;set;} // Binding the json string from database
public List<Employee> Employees { get { return JsonConvert.DeserializeObject<Employee>(JsonEmployeeText );}} //Converting the retrieved json string from Database to c# entity
}
I guess we should not do any sort of database logic on getters as it can sometimes delay the process of initialization in case we need to use this we need to make sure we enable the lazy loading
I have something like this in my repository class in a Spring project:
#Query(value = "SELECT * FROM accounts WHERE (first_name LIKE %:firstName% AND last_name LIKE %:lastName%)", nativeQuery = true)
public List<Account> searchByFirstnameAndLastname(#Param("firstName")String firstName,#Param("lastName")String lastName);
I want it to return everything if the parameters are not provided. Even the ones with null firstname/lastname. And it ignores the null values because of the wildcard used. Since null is different from ''.
I was thinking of an if-statement structure and building the query in runtime based on the provided parameters and then setting the value for the #Query annotation.
I tried generating the where clause and passing it as a parameter but it didn't work. I guess the way Spring Data JPA processes the value of this annotation caused it.
Any idea what is the best solution to this?
Have you tried containing keyword like below :
List<Account> findByFirstnameContainingAndLastNameContaining(String firstName,String lastName);
Docs: https://docs.spring.io/spring-data/jpa/docs/current/reference/html/
You cannot go far with #Query
For dynamic queries(with many optional filters), the way to go is using Criteria API or JPQL. I suggest the Criteria API as it is object oriented and suitable for dynamic queries.
I would suggest to use QueryDSL. It is mentioned in the docs JB Nizet already posted. There is is nice but quite old tutorial here.
With QueryDSL it is very convenient to create your queries dynamically and it is easier to understand than the JPA Criteria API.
The only difficulty in using QueryDSL is the need to automatically create the query objects from your entities but this can be automated by using maven.
There are two ways to handle your situation.
The hard way is using RepositoryFactoryBean as follow
create a custom RepositoryFactoryBean
public class DaoRepositoryFactoryBean, T, I extends Serializable>
extends JpaRepositoryFactoryBean
{
#Override
protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager)
{
return new DaoRepositoryFactory(entityManager);
}
private static class DaoRepositoryFactory<E extends AbstractEntity, I extends Serializable> extends JpaRepositoryFactory
{
private EntityManager entityManager;
public DaoRepositoryFactory(EntityManager entityManager)
{
super(entityManager);
this.entityManager = entityManager;
}
#Override
protected Object getTargetRepository(RepositoryMetadata metadata)
{
return new DaoImpl<E>((Class<E>) metadata.getDomainType(), entityManager);
}
#Override
protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata)
{
return Dao.class;
}
}
}
create Dao interface
#NoRepositoryBean
public interface Dao extends JpaRepository
{
List findByParamsOrAllWhenEmpty();
}
create your implementation
#Transactional(readOnly = true)
public class DaoImpl extends SimpleJpaRepository implements Dao
{
private EntityManager entityManager;
public DaoImpl(Class<E> domainClass, EntityManager em)
{
super(domainClass, em);
this.entityManager = em;
this.domainClass = domainClass;
}
List<E> findByParamsOrAllWhenEmpty()
{
//implement your custom query logic
//scan your domainClass methods for Query anotations and do the rest
}
}
introduce it to Spring Jpa Data
jpa:repositories
base-package=""
query-lookup-strategy="" factory-class="com.core.dao.DaoRepositoryFactoryBean"
The easy way using Custom Impl which in this case you can't use #Query annotation.
"coalesce" on MySQL or "IsNull" on SQL Server is my preferred solution. They return back the first non-null value of a list and you may use it as a trick to deal with an empty string just like a null:
#Query(value = "SELECT * FROM accounts WHERE (COALESCE(first_name,'') LIKE %:firstName% AND COALESCE(last_name,'') LIKE %:lastName%)", nativeQuery = true)
public List<Account> searchByFirstnameAndLastname(#Param("firstName")String firstName,#Param("lastName")String lastName);
Thanks to the questioner and the answerer :D at this page:
like '%' does not accept NULL value
I would like to create a calculator application that can switch between different number bases. As far as entering digits is concerned, I was thinking the following would be a flexible api:
public interface ICalculator
{
string Enter(INumberElement element);
}
public class BaseTenCalculator : ICalculator
{
public string Enter(INumberElement element)
{
...
}
}
public class BaseTwoCalculator : ICalculator
{
public string Enter(INumberElement element)
{
...
}
}
My problem is that for the BaseTenCalculator, I would like a method
Enter(BaseTenNumberElement element)
and for a BaseTwoCalculator, I would like a method
Enter(BaseTwoNumberElement element)
to make sure only valid digits for that number base get entered. However, the only way I can think of enforcing this constraint is downcasting the 'element' argument in the two different implementations, and throwing an exception if INumberElement is not of the correct type. I feel like this is 'wrong', and I'm missing something. Is there another way? Is it even possible to create a common interface for two different number base calculators?
public interface ICalculator<in T> where T : INumberElement
{
string Enter(T element);
}
public class BaseTenCalculator : ICalculator<BaseTenNumberElement>
{
public string Enter(BaseTenNumberElement element)
{
throw new NotImplementedException();
}
}
public class BaseTwoCalculator : ICalculator<BaseTwoNumberElement>
{
public string Enter(BaseTwoNumberElement element)
{
throw new NotImplementedException();
}
}
I think you're thinking of the problem incorrectly. A number is a number regardless of base. Base is only a visible representation of the number. A good example to work from might be BigInteger. It has a constructor: BigInteger(String val, int radix), and a function: toString(int radix). All the work of representing the number is done the same. The only thing that differs is parsing from a string representation into the number, and then getting back out into a number format in a particular base.
You could create a multi-base calculator by using BigInteger or BigDecimal underneath and just using a base selection to set the radix value to parse or print the number(s). You'd also want to limit the input buttons (assuming you're using buttons), but that's really just a counting problem.
Im trying to write an aplication with uses hibernate to write to database, however in some actions i have to use JDBC on data in tables made by HB.
JDBS is requred to give administrator ability to create SQL queries with will return statistic info about data in database like number of processed document of specified type, numbers of success/failed log in attempts or total value of products in orders.
To do that i've done an from that allows to create class that has override toString() with return nice sql query string.
All works but now im trying to make administrator live easier by hiving him an ability to choose of table/column names. And here is an problem, because they are created by hibernate. some by #column annotation other by field name.
How can i check how field mapping?
I know its all about reflections but didnt do much of that in java yet.
example
#Entity
#Table(name= "my_table_name" )
public class TableOFSomething implements Serializable{
//This field isn't mapped into database and info about it is not requred.
//In fact, info about it may cause an error.
private static final long serialVersionUID = 7L;
#Id
#Column(name="id")
private String id;
private String fieldOne;
#Column(name="field_two")
private String fieldTwo;
#Column(name="renamed_just_for_fun")
private int Number;
//code with getters & setters
}
How to write methods that will have definition like
public <T> String tableName(Class<T> Target); //returns name of table in database
public <T> ArrayList<String> tabelFields(Class<T> Target); //returns name of fields in database
Hibernate has API - getClassMetadata that can explore the mapping. The API might change and is now located in another place , but i will use it and not in reflection for this.
look on this post for more details:
Get the table name from the model in Hibernate
if you want reflection , so use this link
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import javax.persistence.Column;
import javax.persistence.Table;
import odi.beans.statistic.QueryBean;
public class ReflectionTest {
public static void main(String[] args) {
ReflectionTest test=new ReflectionTest();
System.out.println("Table name of "+QueryBean.class.getName()+" is "+test.getTableName(QueryBean.class));
System.out.println("Column names in this table are:");
for(String n: test.getColumnNames(QueryBean.class)){
System.out.println("\t"+n);
}
System.out.println("Good bye ;)");
}
public <T> ArrayList<String> getColumnNames(Class<T> target) {
ArrayList<String> ret=new ArrayList<>();
Field[] fields = target.getDeclaredFields();
String fieldName =null;
for (Field f : fields) {
//jump to next if if field is static
if (Modifier.isStatic(f.getModifiers()))
continue;
if (f.isAnnotationPresent(Column.class)) {
Column a = f.getAnnotation(Column.class);
fieldName = a.name();
} else {
fieldName = f.getName();
}
ret.add(fieldName);
}
return ret;
}
public <T> String getTableName(Class<T> target){
String ret=target.getSimpleName();
if (target.isAnnotationPresent(Table.class))
{
Table t=target.getAnnotation(Table.class);
ret=t.name();
}
return ret;
}
}
Is it cover all possibilities?
I know now that Hibernate way would be easier, but this is also about learning of very useful reflection mechanism :)
EDIT:
Important question:
Will this work only on annotations or also on xml mapping?
I have at least two different classes like following :
//NOTE : these two classes have getter and setter also
class Artist {
String artistName;
String artistWebsite;
String artistDbpedia;
String artistImage;
List<String> astistAlbumsName;
List<String> astistAlbumsUrl;
}
class Venu {
String VenuName;
String VenuWebsite;
String VenuDbpdia;
String VenuImage;
String VenuDescription;
List<String> venuFans;
}
I want to have a producer class to get an xml file as an input and detect the type of xml (venu/artist) then start to create a product object based on the input.
the problem :
I want to create an interface for aggregate the similarity between above two classes so my interface would be:
interface Model {
public String getImage();
public String getName();
public String getWebsite();
public String getdbpedia();
}
Then I can implement this interface in my builder class and above two classes but how about those different methods?
such as getVenuFans / getArtistAlbumName / etc....?
How can I call them from my producer?
this is my builder :
Class Builder implements Model {
public String getImage(){}
public String getName(){}
public String getWebsite(){}
public String getdbpedia(){}
}
and this can be my producer :
Class Producer {
public Producer()
{
Builder b = null;
//assume Venu and Artist implements Model
b = (Builder) new Venu();
//I don't have access to getVenuFans()!
b = (Builder) new Artist();
//I don't have access to getArtistAlbumsName() / etc...
}
}
You don't have access to those methods because you're casting the objects to a Builder, and Builder doesn't have those methods.
I see what you're trying to do, but I don't think it will work. For example, getVenueFans (I'm assuming you mean venue) is only appropriate for the Venue class. It doesn't make sense to try and abstract that into an interface that other non-Venue classes will implement.
I think what you have is good: You've abstracted the common methods into an interface. To call the methods on Venue and Artist, the consuming code will need to cast the objects to the appropriate type, then call the methods on it. And that's not as bad as you might think. It's the consuming code that knows what type it's dealing with (otherwise, why would it be trying to call getVenueFans?), so that's the point where it makes sense to cast and call the method directly.