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javaspringperformanceif-statementcoding-style

Clean code - Search endpoint with one or more filters with specific rules: How to avoid multiple "ifs"?


if you were developing a search endpoint that can have one or more filters and there are specific rules for combining these filters, how to avoid using multiple "ifs"?

private void addCriteria(ProductFilter filter, Query query) {
//user does not fill anything, throws exception

        if (ObjectUtils.isEmpty(filter.getIds()) && !validateComboFilters(filter)) {
            throw new RequiredFilterException();
        }

//user does not fill id filter but fills other filters

        if (ObjectUtils.isEmpty(filter.getIds()) && validateComboFilters(filter)) {

            query.addCriteria(Criteria.where(Constants.CREATED_AT)
                    .gte(filter.getFromDate())
                    .lte(filter.getToDate()));

            query.addCriteria(Criteria.where(Constants.STATUS).in(filter.getStatus()));
        }

//user fills id filter and one or more other filters

        if (ObjectUtils.isNotEmpty(filter.getIds())) {

            query.addCriteria(Criteria.where(Constants.ID)
                    .is(filter.getIds()));

            if (filter.filterByRangeDate()) {
                query.addCriteria(Criteria.where(Constants.CREATED_AT)
                        .gte(filter.getFromDate())
                        .lte(filter.getToDate()));
            }
            if (filter.filterByStatus()) {
                query.addCriteria(Criteria.where(Constants.STATUS).in(filter.getStatus()));
            }
        }
    }

Solution

  • It could look like this. I didn't check that for compilation, but I think that general approach is more or less correct.

    private static final BiFunction<ProductFilter, Query, Boolean> ADD_CRITERIA_IDS = (filter, query) -> {
        boolean res = ObjectUtils.isNotEmpty(filter.getIds());
        if (res)
            query.addCriteria(Criteria.where(Constants.ID).is(filter.getIds()));
        return res;
    };
    
    private static final BiFunction<ProductFilter, Query, Boolean> ADD_CRITERIA_STATUS = (filter, query) -> {
        boolean res = filter.filterByStatus();
        if (res)
            query.addCriteria(Criteria.where(Constants.STATUS).in(filter.getStatus()));
        return res;
    };
    
    private static final BiFunction<ProductFilter, Query, Boolean> ADD_CRITERIA_DATE_RANGE = (filter, query) -> {
        boolean res = filter.filterByRangeDate();
        if (res)
            query.addCriteria(Criteria.where(Constants.CREATED_AT)
                                      .gte(filter.getFromDate())
                                      .lte(filter.getToDate()));
        return res;
    };
    
    private void addCriteria(ProductFilter filter, Query query) {
        boolean added = ADD_CRITERIA_IDS.apply(filter, query);
        added |= ADD_CRITERIA_STATUS.apply(filter, query);
        added |= ADD_CRITERIA_DATE_RANGE.apply(filter, query);
    
        if (!added)
            throw new RequiredFilterException();
    }