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Custom Query Join in JPA using Criteria Builder API

Currently I am doing it like this:
List<Table1Entity> findAllMatchingEntities(Table1Entity table1Entity) {
String queryString = "SELECT table1.* FROM table1 "
+ "JOIN table2 t2 ON table1.id=t2.table1_id";
if (table1Entity.getName() != null) {
queryString +=" where name like ?";
}
Query query = em.createNativeQuery(queryString, Table1Entity.class);
if (table1Entity.getName() != null) {
query.setParameter(1, table1Entity.getName())
}
return query.getResultedList();
}
If I want to check more parameters in this join this will quickly turn into a lot of if statements and it would be really complicated to set parameters correctly.
I know I can check parameters with criteria Builder API like this:
if(table1Entity.getName() != null) {
table1EntitySpecification = (root, query, criteriaBuilder)
-> criteriaBuilder.like(
criteriaBuilder.lower(root
.get("name")),
("%" + table1Entity.getName() + "%")
.toLowerCase());;
}
and after that get them all with:
findAll(table1EntitySpecification) with findAll from simpleJPARepository. Now I can chain them together with .or or .and etc. and avoid setting the parameter and checking for null second time.
But how do I do join with criteria APi?
I know I can have in my #Repository something like this:
#Query(value = "SELECT table1.* FROM table1 JOIN table2 t2 ON table1.id=t2.table1_id", nativeQuery = true)
List<Table1Entity> findAllMatchingEntities(Table1Entity table1Entity);
But since name is optional (can be null) I can't just leave it in #Query.
What is the best solution here to avoid using native query and in case of having to check many parameters to avoid using if statements?

I don't know if I fully get your question, but regarding the possibility of nulls, and using the CRUD repository, you can always do a null check before like:
#Query(value = "SELECT table1.* FROM table1 JOIN table2 t2 ON table1.id=t2.table1_id WHERE table1.id is not null", nativeQuery = true)
List<Table1Entity> findAllMatchingEntities(Table1Entity table1Entity);
Depending on what you are trying to achieve, you can always compose the query with similar checks like (not related to your code):
#Query("SELECT c FROM Certificate c WHERE (:id is null or upper(c.id) = :id) "
+ "and (:name is null or upper(c.name) = :name)")
List<Table1> findStuff(#Param("id") String id,
#Param("name") String name);

HQL: Two conditions in where clause returning empty result

I am trying to select from db using HQL with two conditions as below:
String hql = "from User u where u.login=? and u.password=?";
Query query = sessionFactory.getCurrentSession().createQuery(hql);
System.out.println(query);
query.setString(0, u);
query.setString(1, p);
#SuppressWarnings("unchecked")
List<User> listUser = (List<User>) query.list();
System.out.println(listUser);
if (listUser != null && !listUser.isEmpty()) {
return true;
}
return false;
But I am getting empty result. I tried by giving only one condition , then it is giving proper result. (i.e. from User u where u.login=?). How to achieve this with two conditions?

How do i form a query for jdbcTemplate

am trying to form a query based on parameters, if the parameters for WHERE clause is null or not. it seems to be a huge code if i do this on if and else. Is there any other smart way to this??
example :
String query = "SELECT CUSTOMER_NAME FROM CUSTOMER_TABLE WHERE ";
if(cust_id !=null && !(cust_id.trim().equalsIgnoreCase("")))
{
query = query + "cust_id='"+cust_id+"'";
}
else
{
}
checking all the columns like this, the code is looking like a mess, please let me know if there is an other way to do this
adding to the above question :
I also have the parameters for like operator
example
if(strCustName!=null)
{
String query = "SELECT * FROM CUSTOMER WHERE CUSTOMER_NAME LIKE '"+strCustName+"';
}

You can use NamedParameterJDBCTemplate
And your query could be
... WHERE (cust_id=:custIdParam OR :custIdParam is null)
AND (another_column=:another_param OR :another_param is null)
UPDATE:
String sqlstr = "select * from the_table where lastname like :lastname or :lastname is null"
NamedParameterJdbcTemplate jt = new NamedParameterJdbcTemplate(datasource);
Map namedParameters = new HashMap();
namedParameters.put("lastname", "%test%");
SqlRowSet result = jt.queryForRowSet( sqlstr ,namedParameters );
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Need a help to create hibernate query

need a help to create hibernate query that table is jdwCustomerTlrdRef and it should take all the operation_spec = customer name. the method should return sysId.
Here is the code to review. Please help me i am new to this hibernate query.
public getCustomerTlrdRef(BigDecimal sysId) {
System.out.println("---- getAllCustomerTlrdRef " );
String query = "from JdwCustomerTlrdRef as jdwCustomerTlrdRef where jdwCustomerTlrdRef.operation_spec= '+customer_name+'";
Query q = getSessionFactory().getCurrentSession().createQuery(query);
List<JdwCustomerTlrdRef> customerTlrdRefSysId = q.list();
System.out.println(" List size: " + customerTlrdRefSysId.size());
return customerTlrdRefSysId;
}

This should work.
String query = "from JdwCustomerTlrdRef jdwCustomerTlrdRef where jdwCustomerTlrdRef.operation_spec= '+ customer_name +'";
Otherwise if you want to pass the parameter later in your code then do it this way.
String query = "FROM JdwCustomerTlrdRef jdwCustomerTlrdRef WHERE jdwCustomerTlrdRef.operation_spec = :customer_name"
then in your code you can pass the parameter this way.
query.setParameter("customer_name", theCustomerNameParameter);

Filtering results in a JPQL query

I am trying to make "filter" search for all questions in my database. Now I get a exception telling me that I can't compare enum values with string. Is it because I don't use the fully qualified package name of wher the enum type is declared? If so, is it better ways than hard-coding the package name?
Exception Description: Error compiling the query [SELECT q FROM
Question q WHERE q.status = 'APPROVED'], line 1, column 40: invalid
enum equal expression, cannot compare enum value of type
[app.utility.Status} with a non enum value of type
[java.lang.String].
public List<Question> all(Status status, ViewOption viewOption) {
String jpql = "SELECT q FROM Question q ";
boolean isWhereClauseAdded = false;
if (status != Status.ALL) {
if (!isWhereClauseAdded) {
jpql += "WHERE ";
}
jpql += "q.status = '" + status + "'";
}
if (viewOption != ViewOption.ALL) {
if (!isWhereClauseAdded) {
jpql += "WHERE ";
}
// Check if 'AND' operator is needed.
if (status != Status.ALL) {
jpql += " AND ";
}
switch (viewOption) {
case ONLY_IMAGES:
jpql += "q.image != ''";
break;
case NO_IMAGES:
jpql += "q.image = '' ";
break;
}
}
TypedQuery<Question> query = entityManager.createQuery(jpql,
Question.class);
return query.getResultList();
}

The right thing to do would be to use a query parameter:
String jpql = "select ... where q.status = :status";
Query query = em.createQuery(jpql).setParameter("status", status);
Rather than creating your query dynamically be concatenating query parts, you should also use the Criteria API, which has been designed with this goal in mind.

Can you try changing:
jpql += "q.status = '" + status + "'";
To:
jpql += "q.status = app.utility.Status." + status;