ElasticRestClient

A lightweight Java client for interacting with Elasticsearch via REST, supporting document CRUD, bulk operations, advanced search queries, and scrollable search.

Features

• Index, update, delete, and retrieve documents
• Bulk operations (index, update, delete)
• Flexible search with query string and match queries
• Scrollable search for large result sets
• Index management (delete, alias)
• Handles both POJOs and Jackson ObjectNode for document bodies

Getting Started

Prerequisites

• Java 17 or higher
• Maven (for building)
• Elasticsearch instance (tested with 7.x)

Installation

Maven Dependency

Not released yet.

Building from source

1. Clone the repository:

   git clone git@github.com:NiSchie/ElasticRestClient.git
   cd ElasticRestClient

2. Build the project:

   mvn clean package

Usage

1. Create a Client

ElasticRestClient client = new ElasticRestClient(
    "http://localhost:9200", // Elasticsearch host
    "user",                  // Username
    "password"               // Password
);

2. Index a Document

Index index = Index.of("my-index");
Id id = Id.of("doc-id");
Map<String, Object> doc = Map.of("field", "value");
client.document().index(index, id, doc); // POJO or Map, allows update if exists

//index only with auto-generated ID
client.document().index(index, doc); // No ID specified, Elasticsearch generates one

// Or using Jackson ObjectNode
com.fasterxml.jackson.databind.ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
com.fasterxml.jackson.databind.node.ObjectNode jsonDoc = mapper.valueToTree(doc);
client.document().index(index, id, jsonDoc);

3. Get a Document

ElasticDocument doc = client.document().getDocument(index, id);
if (doc == null) {
    // Not found
}

4. Working with ElasticDocument

After retrieving a document, you can access its source and metadata:

if (doc != null) {
    // Get the source as a Map
    Map<String, Object> source = doc.source();
    // Get the source as a Jackson ObjectNode
    com.fasterxml.jackson.databind.node.ObjectNode sourceJson = doc.sourceAsJSON();
    // Get the entire document (including metadata) as a Jackson ObjectNode
    com.fasterxml.jackson.databind.node.ObjectNode fullJson = doc.toJSON();
    // Parse the source directly into a POJO
    MyPojo pojo = doc.sourceAs(MyPojo.class);
}

5. Delete a Document

client.document().delete(index, id);

6. Search Documents

StringSearchQuery query = StringSearchQuery.of("field:value AND other:foo");
List<ElasticDocument> results = client.document().searchDocuments(index, query);

7. Count Documents by Query

Long count = client.document().countByQuery(index, query);

8. Delete by Query

client.document().deleteByMatchQuery(index, query);

9. Bulk Operations

BulkClient bulk = client.bulk();
bulk.addIndexRequest(index, id, doc); // POJO, Map, or Jackson ObjectNode
bulk.addUpdateRequest(index, id, Map.of("field", "newValue")); // Update specific fields
bulk.addDeleteRequest(index, id);
bulk.executeBulk(true); // Force execution

10. Scrollable Search

ScrollableSearch scroll = client.scrollSearch(index, query, 100);
List<ElasticDocument> hits;
while (scroll.scroll()) {
    hits = scroll.getSearchHits();
    // process hits
}

• The scroll() method performs the initial search on the first call and fetches the next page on subsequent calls using the scroll ID.
• It returns the current page of hits as a List<ElasticDocument>, or an empty list if there are no more results.

11. Index Management

client.index().deleteIndex(index);
client.index().alias(index, "alias-name");

Notes

• All document methods accept POJOs, Maps, or Jackson ObjectNode/ArrayNode.
• JSON serialization is handled automatically.
• Error handling: getDocument returns null if not found; other methods throw on error.