fix: add support for custom mapping in ElasticsearchDocumentStore

integrations/elasticsearch/src/haystack_integrations/document_stores/elasticsearch/document_store.py

@@ -63,6 +63,7 @@ def __init__(
         self,
         *,
         hosts: Optional[Hosts] = None,
+        custom_mapping: Optional[Dict[str, Any]] = None,
         index: str = "default",
         embedding_similarity_function: Literal["cosine", "dot_product", "l2_norm", "max_inner_product"] = "cosine",
         **kwargs,
@@ -82,6 +83,7 @@ def __init__(
         [reference](https://elasticsearch-py.readthedocs.io/en/stable/api.html#module-elasticsearch)
 
         :param hosts: List of hosts running the Elasticsearch client.
+        :param custom_mapping: Custom mapping for the index. If not provided, a default mapping will be used.
         :param index: Name of index in Elasticsearch.
         :param embedding_similarity_function: The similarity function used to compare Documents embeddings.
             This parameter only takes effect if the index does not yet exist and is created.
@@ -98,29 +100,37 @@ def __init__(
         )
         self._index = index
         self._embedding_similarity_function = embedding_similarity_function
+        self._custom_mapping = custom_mapping
         self._kwargs = kwargs
 
         # Check client connection, this will raise if not connected
         self._client.info()
 
-        # configure mapping for the embedding field
-        mappings = {
-            "properties": {
-                "embedding": {"type": "dense_vector", "index": True, "similarity": embedding_similarity_function},
-                "content": {"type": "text"},
-            },
-            "dynamic_templates": [
-                {
-                    "strings": {
-                        "path_match": "*",
-                        "match_mapping_type": "string",
-                        "mapping": {
-                            "type": "keyword",
-                        },
+        if self._custom_mapping and not isinstance(self._custom_mapping, Dict):
+            msg = "custom_mapping must be a dictionary"
+            raise ValueError(msg)
+
+        if self._custom_mapping:
+            mappings = self._custom_mapping
+        else:
+            # Configure mapping for the embedding field if none is provided
+            mappings = {
+                "properties": {
+                    "embedding": {"type": "dense_vector", "index": True, "similarity": embedding_similarity_function},
+                    "content": {"type": "text"},
+                },
+                "dynamic_templates": [
+                    {
+                        "strings": {
+                            "path_match": "*",
+                            "match_mapping_type": "string",
+                            "mapping": {
+                                "type": "keyword",
+                            },
+                        }
                     }
-                }
-            ],
-        }
+                ],
+            }
 
         # Create the index if it doesn't exist
         if not self._client.indices.exists(index=index):
@@ -139,6 +149,7 @@ def to_dict(self) -> Dict[str, Any]:
         return default_to_dict(
             self,
             hosts=self._hosts,
+            custom_mapping=self._custom_mapping,
             index=self._index,
             embedding_similarity_function=self._embedding_similarity_function,
             **self._kwargs,

integrations/elasticsearch/tests/test_bm25_retriever.py

@@ -28,6 +28,7 @@ def test_to_dict(_mock_elasticsearch_client):
             "document_store": {
                 "init_parameters": {
                     "hosts": "some fake host",
+                    "custom_mapping": None,
                     "index": "default",
                     "embedding_similarity_function": "cosine",
                 },

integrations/elasticsearch/tests/test_document_store.py

@@ -4,7 +4,7 @@
 
 import random
 from typing import List
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 import pytest
 from elasticsearch.exceptions import BadRequestError  # type: ignore[import-not-found]
@@ -23,6 +23,7 @@ def test_to_dict(_mock_elasticsearch_client):
         "type": "haystack_integrations.document_stores.elasticsearch.document_store.ElasticsearchDocumentStore",
         "init_parameters": {
             "hosts": "some hosts",
+            "custom_mapping": None,
             "index": "default",
             "embedding_similarity_function": "cosine",
         },
@@ -35,13 +36,15 @@ def test_from_dict(_mock_elasticsearch_client):
         "type": "haystack_integrations.document_stores.elasticsearch.document_store.ElasticsearchDocumentStore",
         "init_parameters": {
             "hosts": "some hosts",
+            "custom_mapping": None,
             "index": "default",
             "embedding_similarity_function": "cosine",
         },
     }
     document_store = ElasticsearchDocumentStore.from_dict(data)
     assert document_store._hosts == "some hosts"
     assert document_store._index == "default"
+    assert document_store._custom_mapping is None
     assert document_store._embedding_similarity_function == "cosine"
 
 
@@ -280,3 +283,33 @@ def test_write_documents_different_embedding_sizes_fail(self, document_store: El
 
         with pytest.raises(DocumentStoreError):
             document_store.write_documents(docs)
+
+    @patch("haystack_integrations.document_stores.elasticsearch.document_store.Elasticsearch")
+    def test_init_with_custom_mapping(self, mock_elasticsearch):
+        custom_mapping = {
+            "properties": {
+                "embedding": {"type": "dense_vector", "index": True, "similarity": "dot_product"},
+                "content": {"type": "text"},
+            },
+            "dynamic_templates": [
+                {
+                    "strings": {
+                        "path_match": "*",
+                        "match_mapping_type": "string",
+                        "mapping": {
+                            "type": "keyword",
+                        },
+                    }
+                }
+            ],
+        }
+        mock_client = Mock(
+            indices=Mock(create=Mock(), exists=Mock(return_value=False)),
+        )
+        mock_elasticsearch.return_value = mock_client
+
+        ElasticsearchDocumentStore(hosts="some hosts", custom_mapping=custom_mapping)
+        mock_client.indices.create.assert_called_once_with(
+            index="default",
+            mappings=custom_mapping,
+        )

integrations/elasticsearch/tests/test_embedding_retriever.py

@@ -29,6 +29,7 @@ def test_to_dict(_mock_elasticsearch_client):
             "document_store": {
                 "init_parameters": {
                     "hosts": "some fake host",
+                    "custom_mapping": None,
                     "index": "default",
                     "embedding_similarity_function": "cosine",
                 },