[SpringBoot2.4.3] JPQLを活用

SQLクエリーに似た簡易言語
本格的な検索処理はJPQLを理解する必要がある
1.EntityManagerの用意
2.Queryの作成
3.結果(List)の取得

html

	<table>
	<form action="/find" method="post">
		<tr>
			<td>FIND:</td>
			<td><input type="text" name="fstr" size="20" th:value="${value}"></td></td>
		</tr>
		<tr>
			<td></td>
			<td><input type="submit"></td>
		</tr>
	</form>
	</table>

controller

	@RequestMapping(value="/find", method=RequestMethod.GET)
	public ModelAndView find(ModelAndView mav) {
		mav.setViewName("find");
		mav.addObject("title", "Find Page");
		mav.addObject("msg","MyData sample");
		mav.addObject("value", "");
		Iterable<MyData> list = dao.getAll();
		mav.addObject("datalist", list);
		return mav;
	}
	@RequestMapping(value="/find", method=RequestMethod.POST)
	public ModelAndView search(HttpServletRequest request,
			ModelAndView mav) {
		mav.setViewName("find");
		String param = request.getParameter("fstr");
		if(param =="") {
			mav = new ModelAndView("redirect:/find");
		} else {
			mav.addObject("title","Find result");
			mav.addObject("msg","「" + param + "」の検索結果");
			mav.addObject("value", param);
			List<MyData> list = dao.find(param);
			mav.addObject("datalist", list);
		}
		return mav;
	}

MyDataDao

public interface MyDataDao <T> extends Serializable {
	public List<T> getAll();
	public T findById(long id);
	public List<T> findByName(String name);
	public List<T> find(String fstr);
}

	@Override
	public List<MyData> find(String fstr){
		List<MyData> list = null;
		String qstr = "from MyData where id = :fstr";
		Query query = entityManager.createQuery(qstr).setParameter("fstr", Long.parseLong(fstr));
		list = query.getResultList();
		return list;
	}