[JAVA] Make the where clause variable in Spring Data JPA

Purpose

--Display search results on the list search screen --For the search condition, use the entered item, ignore it in the case of input, and narrow down the where clause

Premise

• FW : spring-boot

procedure

Change repository

--Add to inherit *** JpaSpecificationExecutor *** in the Repository interface to be searched

testRepository

@Repository
public interface TestRepository extends JpaRepository<TestEntity, Integer>, JpaSpecificationExecutor<TestEntity> {

}

-(Supplement) Repository is a mechanism for managing Entity in a list

Specification class preparation

--Create search conditions --This method will be used later as a search condition --Specification class plays the role of search condition used in where clause

testSpecifications

/**
	 *If the matter category exists in the search condition, add it to the where condition
	 * @param anken_kbn
	 * @return
	 */
	public Specification<TestEntity> ankenKbnContains(String anken_kbn) {
		if (Util.stringIsEmpty(anken_kbn))
			return null;
		else
			return new Specification<TestEntity>() {
				@Override
				public Predicate toPredicate(Root<TestEntity> root, CriteriaQuery<?> query,
						CriteriaBuilder cb) {
					return cb.like(root.get("anken_kbn"), "%" + anken_kbn + "%");
				}
			};
	}

--This part creates a partial match search with the item anken_kbn --Prepare methods for the conditions used by chaining with and and or ――Here, there are others

• Anken_name
• Rease_campany_name
  We have a method that you can search with --If the method prepared in the Specification class returns *** null, it will be ignored *** and the search will be performed. -** Returns the passed parameter anken_kbn ** with Util.stringIsEmpty (anken_kbn) and ** null ** if anken_kbu is ** empty string ** --If the value is ** not empty **, you are creating a ** search condition ** and returning the object.

Search using Specification in Dao

--Search conditions can be set in the method chain --At this time, the repository mentioned earlier is required, so define this method where it can be injected, or in this case, take the repository object injected into the controller as the first argument and use it. ing --The second argument Form holds the value passed from the screen.

• public List findBySearchItem(TestRepository testRepository,TestForm form

testDao

@Override
	public List<TestEntity> findBySearchItem(TestRepository testRepository,TestForm form) {
		TestSpecifications spec = new TestSpecifications();
		List<TestEntity> result = TestRepository.findAll(Specifications.where(spec.ankenKbnContains(form.getAnken_kbn()))
				.and(spec.ankenNameContains(form.getAnken_name()))
				.and(spec.reaseCampanyNameContains(form.getRease_campany_name()))
				);
		System.out.println("search results");
		System.out.println(result);

		return result;
	}

--Pass the object to be the search condition to the parameter of findAll method provided by repository interface.

Specifications.where(spec.ankenKbnContains(form.getAnken_kbn()))
				.and(spec.ankenNameContains(form.getAnken_name()))
				.and(spec.reaseCampanyNameContains(form.getRease_campany_name()))

--As mentioned above, chain search conditions with and conditions, etc. --spec is an object of specifications and uses the ankenKbnContains method created in that class. --The next form shows the value received from the screen. It becomes the character string of the search condition

Use from Controler

--In testListForm, put the search result as a list to be returned to the screen. --testDao is injected --testRepository is injected --Use Dao. I just needed an instance of the repository class in Dao, so I'm passing testRepository

testControleller

	@RequestMapping("/search")
	public ModelAndView search(@ModelAttribute("testListForm") TestListForm contractListForm,
			ModelAndView mav) {

		mav.setViewName("index");
		Iterable<TestEntity> testEntityList = testDao.findBySearchItem(testRepository, testListForm);
		
		System.out.println("search results");
		System.out.println(tstEntityList);
		
		mav.addObject("contractList", hdrEntityList);
		mav.addObject("contractListF", new TestListForm());
		return mav;

	}

that's all

--Created a variable where clause by groping ――Is this a good way to write? There may be a better way to write that I don't have.