How to use SQLQueryFactory with your QueryDSL JPA Entities

#java #spring #querydsl #jpa

Even you want QueryDSL SQL features such as bulk insert, you are using queryDSL JPA, unfortunately there is no way to generate RelationalPath<T> from EntityPath<T> automatically.

Dec 7 '18

As @timo Westkämper feedback You can't turn it into a RelationalPath automatically

but you can create RelationalPathBase using your entityPath

RelationalPathBase relationalPathBase= new RelationalPathBase(this.entityPath.getType(), this.entityPath.getMetadata(), "yourSchemaName","yourTableName");

Open Full Answer

But there's a good news. you can wrap RelationalPath<T> from EntityPath<T> manually like this. so, I made util class that wrap RelationalPath<T> from EntityPath<T>.

TL;DR: copy the class below, apply it, and use it.

	import com.querydsl.core.types.EntityPath;
	import com.querydsl.sql.RelationalPath;
	import com.querydsl.sql.RelationalPathBase;

	import javax.persistence.Table;
	import java.lang.reflect.AnnotatedElement;
	import java.util.Objects;
	import java.util.concurrent.ConcurrentHashMap;
	import java.util.concurrent.ConcurrentMap;

	public final class QueryDslUtils {

	/**
	* Simple Type cache (If you want another cache strategy, make it your own.)
	*/
	private static final ConcurrentMap<EntityPath<?>, RelationalPath<?>> relationalMap = new ConcurrentHashMap<>();

	/**
	* Entity Class to SQLQueryFactory RelationalPath
	* @param entityPath
	* @param <T>
	* @return
	*/
	@SuppressWarnings("unchecked")
	public static <T> RelationalPath<T> asRelational(EntityPath<T> entityPath) {
	AnnotatedElement annotatedElement = Objects.requireNonNull(Objects.requireNonNull(entityPath, "entityPath is null").getAnnotatedElement(), "no annotation");
	Table table = Objects.requireNonNull(annotatedElement.getAnnotation(Table.class), "no entity table");
	RelationalPath<?> result = relationalMap.get(entityPath);
	if(result == null)
	relationalMap.put(entityPath, result = new RelationalPathBase<T>(entityPath.getType(), entityPath.getMetadata(), table.schema(), table.name()));
	return (RelationalPath<T>) result;
	}
	}

view raw QueryDslUtils.java hosted with ❤ by GitHub

How to use? that's very simple. when you are using SQLQueryFactory, then just call QueryDslUtils.asRelational to wrap RelationalPath entity and use any SQLQueryFactory's clause.

@Entity
@Table(name = "my_table", schema = "my_schema") // MUST HAVE THIS ANNOTATION!
@Data // for Lombok
public class SomeEntity {
  @Column("some_col")
  private String someColumn;
  // ...getter, setter, etc.
}

EntityPath<SomeEntity> myEntity = QSomeEntity.someEntity;
RelationalPath<SomeEntity> sqlEntity = QueryDslUtils.asRelational(myEntity);

sqlQueryFactory.insert(sqlEntity)...execute();