[英]Select all records if parameter is null else return specfic item in JPA Criteria query
我正在使用JPA,並且如果搜索字段為空並且如果搜索參數不為null,那么我想編寫搜索查詢以獲取所有記錄,然后應用條件查詢。
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<String> cq = cb.createQuery(String.class);
Root<String> query = cq.from(String.class);
cq.where(cb.equal(query.get("id"), '1234567'));
TypedQuery<String> q = entityManager.createQuery(cq);
List<String> results = q.getResultList();
return results;
謝謝
我終於有了使用Criteria API的解決方案。 看看下面的代碼。
public List < Object > retrieveAll(Object obj) {
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery < Object > cq = cb.createQuery(Object.class);
Root < Object > objQuery = cq.from(Object.class);
List < Predicate > predicates = new ArrayList < Predicate > ();
// You can add as many as Predicate you want.
if (null != obj.getName() && !obj.getName().isEmpty()) {
predicates.add(cb.equal(objQuery.get("Name"), obj.getName()));
}
List < Object > results = new ArrayList < Object > ();
if (!predicates.isEmpty()) {
cq.select(objQuery).where(predicates.toArray(new Predicate[] {}));
cq.orderBy(cb.asc(objQuery.get("Name")));
results = entityManager.createQuery(cq).getResultList();
} else {
results = entityManager.createQuery("from Emplyee ORDER BY Name asc").getResultList();
}
return results;
}
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