javax persistence NoResultException No entity found for query

Question

Before I posted this question  I already looked this  but I couldn t get what I was looking for   I know that for the query I wrote there may exist only one row or none at all  So  there is not reason for me to use getResultList     Here is my code   String hql  from DrawUnusedBalance where unusedBalanceDate   today   Query query em createQuery hql   query setParameter  today  new LocalDate      DrawUnusedBalance drawUnusedBalance        DrawUnusedBalance query getSingleResult      we can have only a                                                   single datum per day    System out println drawUnusedBalance toString        The problem is  if there is no row  it throws an exception  and if not it works fine  I know the problem but I am also looking for the best solution    What I wanted is  if there is no row in the DB I wanted to get a null object  instead of getting an exception  so I will insert a new data  if it is not null  I just want to update it   There is one way to handle this  which I believe is not the right way to do it  It is  I will have a try-catch block and if it throws an exception I can write to insert new data in to the DB on the catch block  But I believe there will be a better way

User · Answer

When you don t know whether there are any results  use getResultList        List lt User gt  foundUsers    List lt User gt   query getResultList            if  foundUsers    null    foundUsers isEmpty                  return false            User foundUser   foundUsers get 0

User · Answer

Another option is to use uniqueResultOptional   method  which gives you Optional in result   String hql  from DrawUnusedBalance where unusedBalanceDate   today   Query query em createQuery hql   query setParameter  today  new LocalDate      Optional lt DrawUnusedBalance gt  drawUnusedBalance query uniqueResultOptional

User · Answer

String hql  quot from DrawUnusedBalance where unusedBalanceDate   today quot   DrawUnusedBalance drawUnusedBalance   em unwrap Session class       createQuery hql  DrawUnusedBalance class       setParameter  quot today quot  new LocalDate         uniqueResultOptional        orElseThrow NotFoundException  new

User · Answer

Yes  You need to use the try catch block  but no need to catch the Exception  As per the API it will throw NoResultException if there is no result  and its up to you how you want to handle it   DrawUnusedBalance drawUnusedBalance   null  try  drawUnusedBalance    DrawUnusedBalance query getSingleResult   catch  NoResultException nre     Ignore this because as per your logic this is ok     if drawUnusedBalance    null      Do your logic

User · Answer

When using java 8  you may take advantage of stream API and simplify code to  return  YourEntityClass  entityManager createQuery         getResultList    stream   findFirst      That will give you java util Optional  If you prefer null instead  all you need is        getResultList    stream   findFirst   orElse null

User · Answer

You mentioned getting the result list from the Query  since you don t know that there is a UniqueResult  hence the exception  you could use list and check the size   if  query list   size      1     Since you re not doing a get   to get your unique object a query will be executed whether you call uniqueResult or list

[java] javax.persistence.NoResultException: No entity found for query

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