Additional Weaviate Filter Comparators (#10522)

### Description
When using Weaviate Self-Retrievers, certain common filter comparators
generated by user queries were unimplemented, resulting in errors. This
PR implements some of them. All linting and format commands have been
run and tests passed.
### Issue
#10474
### Dependencies
timestamp module

---------

Co-authored-by: Patrick Randell <prandell@deloitte.com.au>

libs/langchain/langchain/retrievers/self_query/weaviate.py

@@ -1,3 +1,4 @@
+from datetime import date, datetime
 from typing import Dict, Tuple, Union
 
 from langchain.chains.query_constructor.ir import (
@@ -16,12 +17,28 @@ class WeaviateTranslator(Visitor):
     allowed_operators = [Operator.AND, Operator.OR]
     """Subset of allowed logical operators."""
 
-    allowed_comparators = [Comparator.EQ]
+    allowed_comparators = [
+        Comparator.EQ,
+        Comparator.NE,
+        Comparator.GTE,
+        Comparator.LTE,
+        Comparator.LT,
+        Comparator.GT,
+    ]
 
     def _format_func(self, func: Union[Operator, Comparator]) -> str:
         self._validate_func(func)
         # https://weaviate.io/developers/weaviate/api/graphql/filters
-        map_dict = {Operator.AND: "And", Operator.OR: "Or", Comparator.EQ: "Equal"}
+        map_dict = {
+            Operator.AND: "And",
+            Operator.OR: "Or",
+            Comparator.EQ: "Equal",
+            Comparator.NE: "NotEqual",
+            Comparator.GTE: "GreaterThanEqual",
+            Comparator.LTE: "LessThanEqual",
+            Comparator.LT: "LessThan",
+            Comparator.GT: "GreaterThan",
+        }
         return map_dict[func]
 
     def visit_operation(self, operation: Operation) -> Dict:
@@ -29,11 +46,25 @@ class WeaviateTranslator(Visitor):
         return {"operator": self._format_func(operation.operator), "operands": args}
 
     def visit_comparison(self, comparison: Comparison) -> Dict:
-        return {
+        value_type = "valueText"
+        if isinstance(comparison.value, bool):
+            value_type = "valueBoolean"
+        elif isinstance(comparison.value, float):
+            value_type = "valueNumber"
+        elif isinstance(comparison.value, int):
+            value_type = "valueInt"
+        elif isinstance(comparison.value, datetime) or isinstance(
+            comparison.value, date
+        ):
+            value_type = "valueDate"
+            # ISO 8601 timestamp, formatted as RFC3339
+            comparison.value = comparison.value.strftime("%Y-%m-%dT%H:%M:%SZ")
+        filter = {
             "path": [comparison.attribute],
             "operator": self._format_func(comparison.comparator),
-            "valueText": comparison.value,
         }
+        filter[value_type] = comparison.value
+        return filter
 
     def visit_structured_query(
         self, structured_query: StructuredQuery

libs/langchain/tests/unit_tests/retrievers/self_query/test_weaviate.py

@@ -1,3 +1,4 @@
+from datetime import date, datetime
 from typing import Dict, Tuple
 
 from langchain.chains.query_constructor.ir import (
@@ -19,18 +20,75 @@ def test_visit_comparison() -> None:
     assert expected == actual
 
 
+def test_visit_comparison_integer() -> None:
+    comp = Comparison(comparator=Comparator.GTE, attribute="foo", value=1)
+    expected = {"operator": "GreaterThanEqual", "path": ["foo"], "valueInt": 1}
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
+def test_visit_comparison_number() -> None:
+    comp = Comparison(comparator=Comparator.GT, attribute="foo", value=1.4)
+    expected = {"operator": "GreaterThan", "path": ["foo"], "valueNumber": 1.4}
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
+def test_visit_comparison_boolean() -> None:
+    comp = Comparison(comparator=Comparator.NE, attribute="foo", value=False)
+    expected = {"operator": "NotEqual", "path": ["foo"], "valueBoolean": False}
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
+def test_visit_comparison_datetime() -> None:
+    comp = Comparison(
+        comparator=Comparator.LTE,
+        attribute="foo",
+        value=datetime(2023, 9, 13, 4, 20, 0),
+    )
+    expected = {
+        "operator": "LessThanEqual",
+        "path": ["foo"],
+        "valueDate": "2023-09-13T04:20:00Z",
+    }
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
+def test_visit_comparison_date() -> None:
+    comp = Comparison(
+        comparator=Comparator.LT, attribute="foo", value=date(2023, 9, 13)
+    )
+    expected = {
+        "operator": "LessThan",
+        "path": ["foo"],
+        "valueDate": "2023-09-13T00:00:00Z",
+    }
+    actual = DEFAULT_TRANSLATOR.visit_comparison(comp)
+    assert expected == actual
+
+
 def test_visit_operation() -> None:
     op = Operation(
         operator=Operator.AND,
         arguments=[
-            Comparison(comparator=Comparator.EQ, attribute="foo", value=2),
-            Comparison(comparator=Comparator.EQ, attribute="bar", value="baz"),
+            Comparison(comparator=Comparator.EQ, attribute="foo", value="hello"),
+            Comparison(
+                comparator=Comparator.GTE, attribute="bar", value=date(2023, 9, 13)
+            ),
+            Comparison(comparator=Comparator.LTE, attribute="abc", value=1.4),
         ],
     )
     expected = {
         "operands": [
-            {"operator": "Equal", "path": ["foo"], "valueText": 2},
-            {"operator": "Equal", "path": ["bar"], "valueText": "baz"},
+            {"operator": "Equal", "path": ["foo"], "valueText": "hello"},
+            {
+                "operator": "GreaterThanEqual",
+                "path": ["bar"],
+                "valueDate": "2023-09-13T00:00:00Z",
+            },
+            {"operator": "LessThanEqual", "path": ["abc"], "valueNumber": 1.4},
         ],
         "operator": "And",
     }
@@ -78,7 +136,7 @@ def test_visit_structured_query() -> None:
             "where_filter": {
                 "operator": "And",
                 "operands": [
-                    {"path": ["foo"], "operator": "Equal", "valueText": 2},
+                    {"path": ["foo"], "operator": "Equal", "valueInt": 2},
                     {"path": ["bar"], "operator": "Equal", "valueText": "baz"},
                 ],
             }