JPACriteria Bean

Objective

Make a search query with JPA simple by using a bean holding filter criteria defined via annotations to instruct a query builder. Use convention over configuration. Allow for queries which join to other entities.

Examples

Example 1

To generate a query like the following:

	SELECT u FROM User u 
	WHERE u.active = true
	ORDER BY u.username;	

...you just need a bean like so:

	@CriteriaBean(rootEntity = User.class)
	public class UserFilter {

		@Filter
		private boolean active = true;

		@Order
		private String orderByProperty;

		// getters and setters...

	}

Example 2

A more complex example:

	SELECT o FROM Order o 
	INNER JOIN o.customer c
	WHERE o.placed >= {month ago} 
	AND o.status = 'SHIPPED'
	AND c.country = 'GB'
	ORDER BY c.lastname, c.firstname;

...achieved like so:

	@CriteriaBean(type = Order.class)
	public class CustomerFilter {

		@Filter(operator = ComparisonOperator.GTE)
		private Calendar placed;

		@Filter 
		private String status;

		@Filter(joinFrom = "customer")
		private String country;

		@Order
		private List<OrderCriteria> orderByProperties;
		

		// getters and setters...

	}

Example 3

And one more with pagination this time:

	SELECT o FROM Order o 
	INNER JOIN o.customer c
	WHERE o.placed >= {month ago} 
	AND o.status = 'SHIPPED'
	AND c.country = 'GB'
	ORDER BY c.lastname, c.firstname
	LIMIT 20, 10;

...achieved like so:

	@CriteriaBean(type = Order.class)
	public class CustomerFilter {

		@Filter(operator = ComparisonOperator.GTE)
		private Calendar placed;

		@Filter 
		private String status;

		@Filter(joinFrom = "customer")
		private String country;

		@Order
		private List<OrderCriteria> orderByProperties; 
		
		@PageNumber 
		private int resultPageNumber = 2; 
		
		@PageSize
		privage int recordsPerPage = 10;

		// getters and setters...

	}

Components

Annotations

@CriteriaBean Target - TYPE Params Class rootEntity - the starting entity from which joins, if any, will originate

@Filter Target - FIELD Params String propertyName (Optional) - defaults to name of field on criteria bean ComparisonOperator operator (Option) - defaults to EQ enum ComparisonOperator { EQ, NEQ, GT, GTE, LT, LTE, NULL, NOT_NULL} String joinFrom (Optional) - defaults to rootEntity; ignored if no join specified JoinType joinType (Optional) - defaults to INNER, ignored if no join specified

@PaginationValues (Optional) Target - FIELD Understands PaginationParams class in order to extract firstResult and maxResults for JPA query

@PageNumber @PageSize (Optional) Target - FIELD of types int, long, Integer, Long Used to derive firstResult and maxResults for JPA query

@Order (Optional) Target - FIELD of types String, List, OrderCriteria or List Used to indicate order criteria Params boolean ascending (Optional) - defaults to true, ignored if OrderCriteria / List is used class OrderCriteria { String propertyName; boolean ascending; }

Query builder

Consructed with a @CriteriaBean and an EntityManager

getCountQuery() - returns a Query which can be executed to return the count of all records matching the filter criteria getQuery() - returns a Query which can be executed to return records (in object form) matching the filter criteria