Rewrite query in JPA - jpa

Question

I want to rewrite this SQL query in JPA.
String hql = "SELECT date(created_at) AS cdate, sum(amount) AS amount, count(id) AS nooftransaction "
+ "FROM payment_transactions WHERE date(created_at)>=date(now()- interval 10 DAY) "
+ "AND date(created_at)<date(now()) GROUP BY date(created_at)";
TypedQuery<Merchants> query = entityManager.createQuery(hql, Merchants.class);
List<Merchants> merchants = query.getResultList();
Is there a way to rewrite the queries into JPA or I should use it as it is?

Answer 1

In situations like these, more often than not the best approach is to write a plain SQL view:
CREATE OR REPLACE VIEW payment_transactions_stats AS
SELECT date(created_at) AS cdate, sum(amount) AS amount, count(id) AS nooftransaction
FROM payment_transactions
WHERE date(created_at)>=date(now()- interval 10 DAY)
AND date(created_at)<date(now()) GROUP BY date(created_at);
And map it to an #Immutable entity. This approach works well when:
you have read only data
the view does not need parameters (in this case there are solutions as well which span from hacky to nice)

Answer 2

You provide no details about the classes and entities but it could be something like:
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple> query = builder.createTupleQuery();
From<PaymentTransaction> tx = query.from(PaymentTransaction.class);
Expression<Long> sumAmount = builder.sum(tx.get("amount"));
Expression<Long> count = builder.count(tx.get("id"));
Expression<Date> createdAt = tx.get("created_at");
query.multiselect(createdAt, sumAmount, count);
query.where(builder.greaterThanOrEqualTo(createdAt, builder.function("DATEADD", "DAY", new Date(), builder.literal(-10))),
builder.lessThan(createdAt, new Date()));
query.groupBy(createdAt);
entityManager.createQuery(query).getResultList().stream()
.map(t -> new Merchants(t.get(0, Date.class), t.get(1, Long.class), t.get(2, Long.class)))
.collect(Collectors.toList());

Answer 3

It is better not to use JPA for complex queries like this. JPA are usually used for simple queries.

Answer 4

Since the question is tagged with spring-data-jpa, you could try using a Spring CRUDRepository on top of your table. In the CRUDRepository, write a custom method with the #Query annotation.
It's hard for me to formulate the entire query because I don't know the members of your Merchants class.
Alternatively you can set the nativeQuery = true for the #Query annotation and use actual DB query to solve your problem.

Answer 5

You can use below code
CriteriaBuilder qb = entityManager.getCriteriaBuilder();
CriteriaQuery cq = qb.createQuery();
Root paymentInstructionsRoot = cq.from(PaymentInstructions.class);
List<Predicate> predicates = new ArrayList<>();
predicates.add(qb.greaterThanOrEqualTo(path, fromDateRange));
predicates.add(qb.lessThanOrEqualTo(path, toDateRange));
Selection cdate = paymentInstructionsRoot.get(PaymentInstructions_.createdAt).alias("cdate");
Selection amount = qb.sum(paymentInstructionsRoot.get(PaymentInstructions_.amount))).alias("amount");
Selection nooftransaction = qb.count(paymentInstructionsRoot.get(PaymentInstructions_.id))).alias("nooftransaction");
Selection[] selectionExpression = {cdate, amount, nooftransaction};
Expression[] groupByExpression = {paymentInstructionsRoot.get(PaymentInstructions_.createdAt)};
cq.multiselect(selectionExpression).where(predicates.toArray(new Predicate[]{})).groupBy(groupByExpression).where(predicates.toArray(new Predicate[]{}));
List<PaymentInstructions> paymentInstructions = entityManager.createQuery(cq).getResultList();

Answer 6

In your Entity class that represents the 'payment_transactions' table, add the following:
#SqlResultSetMapping(
name = "PaymentTransaction.summaryMapping",
classes = {
#ConstructorResult(targetClass = PaymentTransactionSummary.class,
columns = {
#ColumnResult(name = "cdate")
, #ColumnResult(name = "amount")
, #ColumnResult(name = "nooftransaction")
})
}
)
Create a new pojo class named PaymentTransactionSummary (must match the name used above, or whatever name you choose, with member fields cdate, amount, and nooftransaction. Include a constructor that includes those three fields in the order listed above.
Then in your dao class, write this:
Query q = entityManager.createNativeQuery("your query string from above"
, "PaymentTransaction.summaryMapping");
List<PaymentTransactionSummary> results = q.getResultList();