Agfdhyk

Currently I am using Query DSL in my Java(with JPA) EE project. I recieve a filterObject from UI as json with all the filters. My FilterObject looks like this

public class FilterObject {



    private String name;

    private List<Status> status;

    private String module;

    private List<Source> source;

    ......

}

And in my service class I have something like this

 public List<MyModel> findByFilter(FilterObject filterObject) {

        BooleanBuilder builder = new BooleanBuilder();



        QMyModel mymodel= QMyModel.myModel;



        if(filterObject.getName() != null) {

            builder.and(mymodel.name.contains(filterObject.getName()));

        }

        if(! CollectionUtils.isEmpty(filterObject.getStatus())) {

            builder.and(mymodel.status.in(filterObject.getStatus()));

        }

        ...............

        ...............

}

And finally I have this

JPAQuery<MyModel> query = new JPAQuery<>(getEntityManager());

List<MyModel> myModels =  query.from(QMyModel.mymodel).where(builder).fetch();

EDIT:

/**

 * QMyModel is a Querydsl query type for MyModel

 */

@Generated("com.querydsl.codegen.EntitySerializer")

public class QMyModel extends EntityPathBase<MyModel> {



    private static final long serialVersionUID = 1041638507L;



    private static final PathInits INITS = PathInits.DIRECT2;



    public static final QMyModel myModel = new QMyModel("myModel");



    public final StringPath name = createString("name");



    public final EnumPath<Status> status = createEnum("status", Status.class);



    public final StringPath module = createString("module");



     ........

     .......

}

All these work. But my FilterObject is growing and has more than 10 fields. So I have like 10 If blocks in my service class method. Is there a better way to do this where I could avoid so many if blocks.

You can use lambda's, or (even better in this case) method reference:

public List<MyModel> findByFilter(FilterObject filterObject) {

    BooleanBuilder builder = new BooleanBuilder();



    QMyModel mymodel = QMyModel.myModel;



    add(builder, filterObject.getName(), mymodel.name::contains);

    add(builder, filterObject.getStatus(), mymodel.status::in);



    ...

}



private <T> void add(BooleanBuilder builder, T filterElement, Function<T, BooleanExpression> booleanExpressionFunction) {

    if (valid(filterElement)) {

        builder.and(booleanExpressionFunction.apply(filterElement));

    }

}



private boolean valid(Object filterElement) {

    if (filterElement == null) {

        return false;

    }

    if (filterElement instanceof Collection) {

        return !((Collection) filterElement).isEmpty();

    }

    return true;

}