java - Spring Elasticsearch : Howto search across multiple indexes with mappings to different objects

Question

首先很抱歉，如果有人问过这个问题，我到处搜索都没有结果。

基本上我有一个具有 3 个索引的 ES 实例。索引的数据/映射是从我的 java POJO 生成的。现在我可以单独搜索每个索引并将其映射回给定的 Pojo/类。

但是，当我想一次性搜索 3 个索引并将搜索命中映射到正确的 Pojo 时，我完全不知所措。

例如，这是我目前如何搜索映射到我拥有的 UserProfile 对象的单个索引:

    public Iterable<UserProfile> fetchUserSearchSuggestions(String query, Integer page, Integer size) {

        PageRequest pageRequest = PageRequest.of(page, size);

        QueryBuilder queryBuilder = QueryBuilders.boolQuery().should(new WildcardQueryBuilder("displayName", query + "*"))
                .should(new WildcardQueryBuilder("name", query + "*"));

        Query searchQuery = new NativeSearchQueryBuilder()
                .withFilter(queryBuilder)
                .withPageable(pageRequest)
                .build();

        SearchHits<UserProfile> searchSuggestions =
                elasticsearchOperations.search(searchQuery,
                        UserProfile.class,
                        IndexCoordinates.of(elasticUserIndex));

        List<UserProfile> suggestions = new ArrayList<>();

        searchSuggestions.getSearchHits().forEach(searchHit -> {
            suggestions.add(searchHit.getContent());
        });
        long totalCount = searchSuggestions.getTotalHits();
        Page<UserProfile> resultPage = PageableExecutionUtils.getPage(
                suggestions,
                pageRequest,
                () -> totalCount);
        return resultPage;
    }

同样，我的问题是，如果我想一次性搜索所有索引，例如通用搜索，并将用户结果映射到 UserProfile 类，等等，对于我拥有的每个不同对象，我该怎么做。

感谢阅读

Answer 1

你知道 MultiSearchRequest 吗？

假设我们有一个具有这种结构的请求类:

class Request {
    private String index;
    private String field;
    private String value;
}

• index - ElasticSearch 索引
• field - 我们正在寻找的领域
• 值 - 字段值

跨多个索引的搜索看起来像这样

   public MultiSearchResponse find(List<Request> requests) throws IOException {
    
    MultiSearchRequest multiSearchRequest = new MultiSearchRequest();

    for (Request req : requests){
        QueryBuilder queryBuilder = QueryBuilders.boolQuery()
                .must(QueryBuilders.matchBoolPrefixQuery(req.field, req.value));

        SearchSourceBuilder builder = new SearchSourceBuilder();
        builder.size(1);
        builder.query(queryBuilder);

        SearchRequest searchRequest = new SearchRequest();
        searchRequest.searchType(SearchType.DFS_QUERY_THEN_FETCH);
        searchRequest.indices(req.index);
        searchRequest.source(builder);

        multiSearchRequest.add(searchRequest);
    }

    return restHighLevelClient.msearch(multiSearchRequest, RequestOptions.DEFAULT);
}

我不知道我的解决方案是否有帮助，但还是

--更新--

在我的宠物项目中，我是这样的转换器

public static List<SensorValueElasticsearch> parse(MultiSearchResponse response) {

    List<SensorValueElasticsearch> values = new ArrayList<>();
    
    for (MultiSearchResponse.Item item : response.getResponses()){
        if (item.getResponse().getHits().getTotalHits().value > 0){
            values.addAll(convertToList(item.getResponse()));
        }
    }
    return values;
}

public static List<SensorValueElasticsearch> convertToList(SearchResponse response) {
    SearchHit[] res = response.getHits().getHits();

    List<SensorValueElasticsearch> list = new LinkedList<>();

    for (SearchHit sh : res) {

        SensorValueElasticsearch object = null;
        try {
            object = OBJECT_MAPPER.readValue(sh.getSourceAsString(), SensorValueElasticsearch.class);
        } catch (JsonProcessingException e) {
            LOGGER.warn("Error while convert SearchResponse to SensorValueElasticsearch", e);
        }

        list.add(object);
    }

    return list;
}

在 OBJECT_MAPPER.readValue 之前的情况下，您必须检查您收到的是哪种对象，或者像这样用 try-catch block 编写返回:

        ObjectA a = null;
        ObjectB b = null;

        try {
            return OBJECT_MAPPER.readValue(sh.getSourceAsString(), ObjectA.class);
        } catch (JsonProcessingException e) {
            // ignore
        }

        try {
            return OBJECT_MAPPER.readValue(sh.getSourceAsString(), ObjectB.class);
        } catch (JsonProcessingException e) {
            // ignore
        }

        throw new IllegalArgumentException("Unknown class");