How to build a query with Panache which depends on optional fields? - quarkus-panache

Question

Let's say I have the following database entity:
Customer
- firstname
- lastname
- status (active | inactive)
- email
And the following (simplified) Java method:
getCustomers (String firstname, String lastname, String status, String email) {...}
If all strings are empty I want to retrieve all records from the database. If lastname and status have values I want to retrieve the relevant records. And so on. So when creating the query I need to check if the fields have values and then add these fields to the database query. How would I best implement this with Quarkus Panache?

Answer 1

I don't think there is a specific method to do it but if you pass the parameters as Map<String, Object>:
public List<Customer> getCustomers(Map<String, Object> parameters)
if ( parameters == null ) {
return Customer.listAll();
}
Map<String, Object> nonNullParams = parameters.entrySet().stream()
.filter( entry -> entry.getValue() != null )
.collect( Collectors.toMap( Map.Entry::getKey, Map.Entry::getValue ) );
if ( nonNullParams.isEmtpty() ) {
return Customer.listAll();
}
String query = nonNullParams.entrySet().stream()
.map( entry -> entry.getKey() + "=:" + entry.getKey() )
.collect( Collectors.joining(" and ") );
return Customer.find(query, nonNullParams);
}
or
public List<Customer> getCustomers (String firstname, String lastname, String status, String email) {
Map<String, Object> parameters = new HashMap<>();
addIfNotNull(parameters, "firstName", firstName );
addIfNotNull(parameters, "lastName", lastName );
addIfNotNull(parameters, "status", status );
addIfNotNull(parameters, "email", email );
if ( parameters.isEmtpty() ) {
return Customer.listAll();
}
String query = parameters.entrySet().stream()
.map( entry -> entry.getKey() + "=:" + entry.getKey() )
.collect( Collectors.joining(" and ") );
return Customer.find(query, parameters)
}
private static void addIfNotNull(Map<String, Object> map, String key, String value) {
if (value != null) {
map.put(key, value);
}
}

Answer 2

You can use filters for this, which is a Hibernate feature supported by Panache. It's not very well documented, so here is a working example.
Your database entity:
#Entity
#Table(name = "book")
#FilterDef(name = "Books.byISBN",
defaultCondition = "isbn = :isbn",
parameters = #ParamDef(isbn = "isbn", type = "string"))
#Filter(name = "Books.byISBN")
public class Book extends PanacheBaseEntity {}
Your web resource
#Path("book")
public class BookResource {
#Inject
BookRepository bookRepository;
#GET
#Produces(MediaType.TEXT_PLAIN)
public String index(#QueryParam("isbn") Optional<String> isbnFilter) {
final PanacheQuery<Book> bookQuery = bookRepository.findAll();
isbnFilter.ifPresent(isbn -> bookQuery.filter("Book.byISBN", Parameters.with("isbn", isbn)));
return bookQuery.list().stream()
.map(Book::name)
.collect(Collectors.joining(","));
}
}