# Java ElasticsearchClient: Conditionally mapping result hits to a certain object depending on a field or index

**URL:** <https://discuss.elastic.co/t/java-elasticsearchclient-conditionally-mapping-result-hits-to-a-certain-object-depending-on-a-field-or-index/337524>\
**Category:** Elasticsearch\
**Tags:** language-clients\
**Created:** [July 4, 2023, 7:33am UTC](https://discuss.elastic.co/t/java-elasticsearchclient-conditionally-mapping-result-hits-to-a-certain-object-depending-on-a-field-or-index/337524 "2023-07-04T07:33:09Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![paulwellnerbou](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/paulwellnerbou/32/85165_2.png) [@paulwellnerbou](https://discuss.elastic.co/u/paulwellnerbou)\
**Post date:** [July 4, 2023, 7:33am UTC](https://discuss.elastic.co/t/java-elasticsearchclient-conditionally-mapping-result-hits-to-a-certain-object-depending-on-a-field-or-index/337524/1 "2023-07-04T07:33:09Z")

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Using the Java ElasticsearchClient, is it possible to create a custom mapper, so that depending on a certain field (or index) of the result hit, a different object is mapped?

I have several indices with different, but very similar documents. The base properties are the same in all of them. And if I query for a list of IDs, I ususally query for (similar) objects in different indices. Ideally I want to have a result list `List<? extends BaseDocument>` with potentially different objects in it, all of them extending my `BaseDocument`.

Of course, one approach would be to this in my `BaseDocument`, which will store all unmapped properties in a map.

```auto
@JsonAnyGetter
@JsonAnySetter
protected final Map<String, Object> properties = new LinkedHashMap<>();

```

And then, in `SpecialDocument`, I can access those properties by

```auto
public getSpecialProperty() {
    return super.properties.get("specialProperty");
}

```

Another way would be to map all result hits just to a `Map`, and then checking the contents of the map and using a custom `ObjectMapper` to map this map back to my domain objects:

```auto
	public List<? extends BaseDocument> search(final List<String> indices, final Query query) throws IOException {
		final ObjectMapper objectMapper = new ObjectMapper();
		final SearchResponse<Map> searchResponse = elasticsearchClient.search(s -> s.index(indices).query(query), Map.class);
		return searchResponse.hits().hits().stream().map(
			hit -> {
				switch (hit.source().get("documentType").toString()) {
					case "specialDocument":
						return objectMapper.convertValue(hit.source(), SpecialDocument.class);
					case "anotherSpecialDocument":
						return objectMapper.convertValue(hit.source(), AnotherSpecialDocument.class);
					default:
						return new BaseDocument();
				}
			}
		).toList();
	}

```

Now, this is mapping the result twice, one time to a `Map`, another time to a concrete object.

Is there a way to pass a mapper to the `ElasticsearchClient` (instead of the `JsonpMapper`, for example?), where I can define conditions to map the result directly to a certain object, instead of treating all results as the same?

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 1, 2023, 7:34am UTC](https://discuss.elastic.co/t/java-elasticsearchclient-conditionally-mapping-result-hits-to-a-certain-object-depending-on-a-field-or-index/337524/2 "2023-08-01T07:34:04Z")

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