multiple: langchain 0.2 in master (#21191)

0.2rc 

migrations

- [x] Move memory
- [x] Move remaining retrievers
- [x] graph_qa chains
- [x] some dependency from evaluation code potentially on math utils
- [x] Move openapi chain from `langchain.chains.api.openapi` to
`langchain_community.chains.openapi`
- [x] Migrate `langchain.chains.ernie_functions` to
`langchain_community.chains.ernie_functions`
- [x] migrate `langchain/chains/llm_requests.py` to
`langchain_community.chains.llm_requests`
- [x] Moving `langchain_community.cross_enoders.base:BaseCrossEncoder`
->
`langchain_community.retrievers.document_compressors.cross_encoder:BaseCrossEncoder`
(namespace not ideal, but it needs to be moved to `langchain` to avoid
circular deps)
- [x] unit tests langchain -- add pytest.mark.community to some unit
tests that will stay in langchain
- [x] unit tests community -- move unit tests that depend on community
to community
- [x] mv integration tests that depend on community to community
- [x] mypy checks

Other todo

- [x] Make deprecation warnings not noisy (need to use warn deprecated
and check that things are implemented properly)
- [x] Update deprecation messages with timeline for code removal (likely
we actually won't be removing things until 0.4 release) -- will give
people more time to transition their code.
- [ ] Add information to deprecation warning to show users how to
migrate their code base using langchain-cli
- [ ] Remove any unnecessary requirements in langchain (e.g., is
SQLALchemy required?)

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/langchain_community/query_constructors/weaviate.py

@@ -0,0 +1,79 @@
+from datetime import datetime
+from typing import Dict, Tuple, Union
+
+from langchain_core.structured_query import (
+    Comparator,
+    Comparison,
+    Operation,
+    Operator,
+    StructuredQuery,
+    Visitor,
+)
+
+
+class WeaviateTranslator(Visitor):
+    """Translate `Weaviate` internal query language elements to valid filters."""
+
+    allowed_operators = [Operator.AND, Operator.OR]
+    """Subset of allowed logical operators."""
+
+    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",
+            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:
+        args = [arg.accept(self) for arg in operation.arguments]
+        return {"operator": self._format_func(operation.operator), "operands": args}
+
+    def visit_comparison(self, comparison: Comparison) -> Dict:
+        value_type = "valueText"
+        value = comparison.value
+        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, dict)
+            and comparison.value.get("type") == "date"
+        ):
+            value_type = "valueDate"
+            # ISO 8601 timestamp, formatted as RFC3339
+            date = datetime.strptime(comparison.value["date"], "%Y-%m-%d")
+            value = date.strftime("%Y-%m-%dT%H:%M:%SZ")
+        filter = {
+            "path": [comparison.attribute],
+            "operator": self._format_func(comparison.comparator),
+            value_type: value,
+        }
+        return filter
+
+    def visit_structured_query(
+        self, structured_query: StructuredQuery
+    ) -> Tuple[str, dict]:
+        if structured_query.filter is None:
+            kwargs = {}
+        else:
+            kwargs = {"where_filter": structured_query.filter.accept(self)}
+        return structured_query.query, kwargs