community[minor]: Self query retriever for HANA Cloud Vector Engine (#24494)

Description:

- This PR adds a self query retriever implementation for SAP HANA Cloud
Vector Engine. The retriever supports all operators except for contains.
- Issue: N/A
- Dependencies: no new dependencies added

**Add tests and docs:**
Added integration tests to:
libs/community/tests/unit_tests/query_constructors/test_hanavector.py

**Documentation for self query retriever:**
/docs/integrations/retrievers/self_query/hanavector_self_query.ipynb

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>
Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>

docs/docs/integrations/retrievers/self_query/hanavector_self_query.ipynb

@@ -0,0 +1,246 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# SAP HANA Cloud Vector Engine\n",
+    "\n",
+    "For more information on how to setup the SAP HANA vetor store, take a look at the [documentation](/docs/integrations/vectorstores/sap_hanavector.ipynb).\n",
+    "\n",
+    "We use the same setup here:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import os\n",
+    "\n",
+    "# Use OPENAI_API_KEY env variable\n",
+    "# os.environ[\"OPENAI_API_KEY\"] = \"Your OpenAI API key\"\n",
+    "from hdbcli import dbapi\n",
+    "\n",
+    "# Use connection settings from the environment\n",
+    "connection = dbapi.connect(\n",
+    "    address=os.environ.get(\"HANA_DB_ADDRESS\"),\n",
+    "    port=os.environ.get(\"HANA_DB_PORT\"),\n",
+    "    user=os.environ.get(\"HANA_DB_USER\"),\n",
+    "    password=os.environ.get(\"HANA_DB_PASSWORD\"),\n",
+    "    autocommit=True,\n",
+    "    sslValidateCertificate=False,\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "To be able to self query with good performance we create additional metadata fields\n",
+    "for our vectorstore table in HANA:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Create custom table with attribute\n",
+    "cur = connection.cursor()\n",
+    "cur.execute(\"DROP TABLE LANGCHAIN_DEMO_SELF_QUERY\", ignoreErrors=True)\n",
+    "cur.execute(\n",
+    "    (\n",
+    "        \"\"\"CREATE TABLE \"LANGCHAIN_DEMO_SELF_QUERY\"  (\n",
+    "        \"name\" NVARCHAR(100), \"is_active\" BOOLEAN, \"id\" INTEGER, \"height\" DOUBLE,\n",
+    "        \"VEC_TEXT\" NCLOB, \n",
+    "        \"VEC_META\" NCLOB, \n",
+    "        \"VEC_VECTOR\" REAL_VECTOR\n",
+    "        )\"\"\"\n",
+    "    )\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's add some documents."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_community.vectorstores.hanavector import HanaDB\n",
+    "from langchain_core.documents import Document\n",
+    "from langchain_openai import OpenAIEmbeddings\n",
+    "\n",
+    "embeddings = OpenAIEmbeddings()\n",
+    "\n",
+    "# Prepare some test documents\n",
+    "docs = [\n",
+    "    Document(\n",
+    "        page_content=\"First\",\n",
+    "        metadata={\"name\": \"adam\", \"is_active\": True, \"id\": 1, \"height\": 10.0},\n",
+    "    ),\n",
+    "    Document(\n",
+    "        page_content=\"Second\",\n",
+    "        metadata={\"name\": \"bob\", \"is_active\": False, \"id\": 2, \"height\": 5.7},\n",
+    "    ),\n",
+    "    Document(\n",
+    "        page_content=\"Third\",\n",
+    "        metadata={\"name\": \"jane\", \"is_active\": True, \"id\": 3, \"height\": 2.4},\n",
+    "    ),\n",
+    "]\n",
+    "\n",
+    "db = HanaDB(\n",
+    "    connection=connection,\n",
+    "    embedding=embeddings,\n",
+    "    table_name=\"LANGCHAIN_DEMO_SELF_QUERY\",\n",
+    "    specific_metadata_columns=[\"name\", \"is_active\", \"id\", \"height\"],\n",
+    ")\n",
+    "\n",
+    "# Delete already existing documents from the table\n",
+    "db.delete(filter={})\n",
+    "db.add_documents(docs)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Self querying\n",
+    "\n",
+    "Now for the main act: here is how to construct a SelfQueryRetriever for HANA vectorstore:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.chains.query_constructor.base import AttributeInfo\n",
+    "from langchain.retrievers.self_query.base import SelfQueryRetriever\n",
+    "from langchain_community.query_constructors.hanavector import HanaTranslator\n",
+    "from langchain_openai import ChatOpenAI\n",
+    "\n",
+    "llm = ChatOpenAI(model=\"gpt-3.5-turbo\")\n",
+    "\n",
+    "metadata_field_info = [\n",
+    "    AttributeInfo(\n",
+    "        name=\"name\",\n",
+    "        description=\"The name of the person\",\n",
+    "        type=\"string\",\n",
+    "    ),\n",
+    "    AttributeInfo(\n",
+    "        name=\"is_active\",\n",
+    "        description=\"Whether the person is active\",\n",
+    "        type=\"boolean\",\n",
+    "    ),\n",
+    "    AttributeInfo(\n",
+    "        name=\"id\",\n",
+    "        description=\"The ID of the person\",\n",
+    "        type=\"integer\",\n",
+    "    ),\n",
+    "    AttributeInfo(\n",
+    "        name=\"height\",\n",
+    "        description=\"The height of the person\",\n",
+    "        type=\"float\",\n",
+    "    ),\n",
+    "]\n",
+    "\n",
+    "document_content_description = \"A collection of persons\"\n",
+    "\n",
+    "hana_translator = HanaTranslator()\n",
+    "\n",
+    "retriever = SelfQueryRetriever.from_llm(\n",
+    "    llm,\n",
+    "    db,\n",
+    "    document_content_description,\n",
+    "    metadata_field_info,\n",
+    "    structured_query_translator=hana_translator,\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's use this retriever to prepare a (self) query for a person:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "query_prompt = \"Which person is not active?\"\n",
+    "\n",
+    "docs = retriever.invoke(input=query_prompt)\n",
+    "for doc in docs:\n",
+    "    print(\"-\" * 80)\n",
+    "    print(doc.page_content, \" \", doc.metadata)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We can also take a look at how the query is being constructed:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.chains.query_constructor.base import (\n",
+    "    StructuredQueryOutputParser,\n",
+    "    get_query_constructor_prompt,\n",
+    ")\n",
+    "\n",
+    "prompt = get_query_constructor_prompt(\n",
+    "    document_content_description,\n",
+    "    metadata_field_info,\n",
+    ")\n",
+    "output_parser = StructuredQueryOutputParser.from_components()\n",
+    "query_constructor = prompt | llm | output_parser\n",
+    "\n",
+    "sq = query_constructor.invoke(input=query_prompt)\n",
+    "\n",
+    "print(\"Structured query: \", sq)\n",
+    "\n",
+    "print(\"Translated for hana vector store: \", hana_translator.visit_structured_query(sq))"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": ".venv",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.10.14"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

libs/community/langchain_community/query_constructors/hanavector.py

@@ -0,0 +1,57 @@
+# HANA Translator/query constructor
+from typing import Dict, Tuple, Union
+
+from langchain_core.structured_query import (
+    Comparator,
+    Comparison,
+    Operation,
+    Operator,
+    StructuredQuery,
+    Visitor,
+)
+
+
+class HanaTranslator(Visitor):
+    """
+    Translate internal query language elements to valid filters params for
+    HANA vectorstore.
+    """
+
+    allowed_operators = [Operator.AND, Operator.OR]
+    """Subset of allowed logical operators."""
+    allowed_comparators = [
+        Comparator.EQ,
+        Comparator.NE,
+        Comparator.GT,
+        Comparator.LT,
+        Comparator.GTE,
+        Comparator.LTE,
+        Comparator.IN,
+        Comparator.NIN,
+        # Comparator.CONTAIN,
+        Comparator.LIKE,
+    ]
+
+    def _format_func(self, func: Union[Operator, Comparator]) -> str:
+        self._validate_func(func)
+        return f"${func.value}"
+
+    def visit_operation(self, operation: Operation) -> Dict:
+        args = [arg.accept(self) for arg in operation.arguments]
+        return {self._format_func(operation.operator): args}
+
+    def visit_comparison(self, comparison: Comparison) -> Dict:
+        return {
+            comparison.attribute: {
+                self._format_func(comparison.comparator): comparison.value
+            }
+        }
+
+    def visit_structured_query(
+        self, structured_query: StructuredQuery
+    ) -> Tuple[str, dict]:
+        if structured_query.filter is None:
+            kwargs = {}
+        else:
+            kwargs = {"filter": structured_query.filter.accept(self)}
+        return structured_query.query, kwargs

libs/community/langchain_community/vectorstores/hanavector.py

@@ -191,7 +191,8 @@ class HanaDB(VectorStore):
                 if column_length is not None and column_length > 0:
                     if rows[0][1] != column_length:
                         raise AttributeError(
-                            f"Column {column_name} has the wrong length: {rows[0][1]}"
+                            f"Column {column_name} has the wrong length: {rows[0][1]} "
+                            f"expected: {column_length}"
                         )
             else:
                 raise AttributeError(f"Column {column_name} does not exist")
@@ -529,10 +530,18 @@ class HanaDB(VectorStore):
                     if special_op in COMPARISONS_TO_SQL:
                         operator = COMPARISONS_TO_SQL[special_op]
                         if isinstance(special_val, bool):
-                            query_tuple.append("true" if filter_value else "false")
+                            query_tuple.append("true" if special_val else "false")
                         elif isinstance(special_val, float):
                             sql_param = "CAST(? as float)"
                             query_tuple.append(special_val)
+                        elif (
+                            isinstance(special_val, dict)
+                            and "type" in special_val
+                            and special_val["type"] == "date"
+                        ):
+                            # Date type
+                            sql_param = "CAST(? as DATE)"
+                            query_tuple.append(special_val["date"])
                         else:
                             query_tuple.append(special_val)
                     # "$between"

libs/community/tests/unit_tests/query_constructors/test_hanavector.py

@@ -0,0 +1,84 @@
+from typing import Dict, Tuple
+
+import pytest as pytest
+from langchain_core.structured_query import (
+    Comparator,
+    Comparison,
+    Operation,
+    Operator,
+    StructuredQuery,
+)
+
+from langchain_community.query_constructors.hanavector import HanaTranslator
+
+DEFAULT_TRANSLATOR = HanaTranslator()
+
+
+def test_visit_comparison() -> None:
+    comp = Comparison(comparator=Comparator.LT, attribute="foo", value=1)
+    expected = {"foo": {"$lt": 1}}
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
+def test_visit_operation() -> None:
+    op = Operation(
+        operator=Operator.AND,
+        arguments=[
+            Comparison(comparator=Comparator.LT, attribute="foo", value=2),
+            Comparison(comparator=Comparator.EQ, attribute="bar", value="baz"),
+            Comparison(comparator=Comparator.GT, attribute="abc", value=2.0),
+        ],
+    )
+    expected = {
+        "$and": [{"foo": {"$lt": 2}}, {"bar": {"$eq": "baz"}}, {"abc": {"$gt": 2.0}}]
+    }
+    actual = DEFAULT_TRANSLATOR.visit_operation(op)
+    assert expected == actual
+
+
+def test_visit_structured_query() -> None:
+    query = "What is the capital of France?"
+    structured_query = StructuredQuery(
+        query=query,
+        filter=None,
+    )
+    expected: Tuple[str, Dict] = (query, {})
+    actual = DEFAULT_TRANSLATOR.visit_structured_query(structured_query)
+    assert expected == actual
+
+    comp = Comparison(comparator=Comparator.LT, attribute="foo", value=1)
+    structured_query = StructuredQuery(
+        query=query,
+        filter=comp,
+    )
+    expected = (query, {"filter": {"foo": {"$lt": 1}}})
+    actual = DEFAULT_TRANSLATOR.visit_structured_query(structured_query)
+    assert expected == actual
+
+    op = Operation(
+        operator=Operator.AND,
+        arguments=[
+            Comparison(comparator=Comparator.LT, attribute="foo", value=2),
+            Comparison(comparator=Comparator.EQ, attribute="bar", value="baz"),
+            Comparison(comparator=Comparator.GT, attribute="abc", value=2.0),
+        ],
+    )
+    structured_query = StructuredQuery(
+        query=query,
+        filter=op,
+    )
+    expected = (
+        query,
+        {
+            "filter": {
+                "$and": [
+                    {"foo": {"$lt": 2}},
+                    {"bar": {"$eq": "baz"}},
+                    {"abc": {"$gt": 2.0}},
+                ]
+            }
+        },
+    )
+    actual = DEFAULT_TRANSLATOR.visit_structured_query(structured_query)
+    assert expected == actual

libs/langchain/langchain/retrievers/self_query/base.py

@@ -177,6 +177,16 @@ def _get_builtin_translator(vectorstore: VectorStore) -> Visitor:
             if isinstance(vectorstore, PGVector):
                 return NewPGVectorTranslator()
 
+        try:
+            # Added in langchain-community==0.2.11
+            from langchain_community.query_constructors.hanavector import HanaTranslator
+            from langchain_community.vectorstores import HanaDB
+        except ImportError:
+            pass
+        else:
+            if isinstance(vectorstore, HanaDB):
+                return HanaTranslator()
+
         raise ValueError(
             f"Self query retriever with Vector Store type {vectorstore.__class__}"
             f" not supported."