QueryDSL dynamic predicate chaining

Question

How to use QueryDSL to dynamically build and chain predicates.

I have a UI with a datatable. Each column has a box where you can enter one filter term. Like so:

In the example above eventno filter = "0288" and address filter = "drive". These are then sent by the UI to the backend in a pagination object, which contains a map of column names and filter strings. Like so:

In my backend with QueryDSL I now need to dynamically construct a Predicate based on the terms provided for the columns. I have tried this for just the address event and address column, but it does not seem to filter both.

public Page<EpisodeDashboard> getPage(int pageNumber, int pageSize, Sort sort, PaginationCriteria pagination) {
    BooleanBuilder where = new BooleanBuilder();
    if (pagination.getFilterBy().getMapOfFilters().get("eventno")!=null) {
        where.and(qEpisode.eventno.containsIgnoreCase(pagination.getFilterBy().getMapOfFilters().get("eventno")));
        }
    if (pagination.getFilterBy().getMapOfFilters().get("address")!=null) {
        where.and(qEpisode.address.formattedAddress.containsIgnoreCase(pagination.getFilterBy().getMapOfFilters().get("address")));
        }
    List<Episode> e = episodeRepository.findAll(where);

I probably want something with a for each key/value in the hashmap to dynamically construct the predicates.

Answer 1

The above code actually works, but :

episodeRepository.findAll(where);

Returns a iterable and most of my project uses List. So I modified the Episode Repo with a override to:

    @Override
    List<Episode> findAll(Predicate predicate);

Now a list is returned and the code works. An enhancement on this answer would be if the "if" statements could be generated by iterating over the pagination filter hashmap.