Add support for Langchain VectorStores (#2518)

mem0/configs/vector_stores/langchain.py

@@ -0,0 +1,30 @@
+from typing import Any, ClassVar, Dict
+
+from pydantic import BaseModel, Field, model_validator
+
+
+class LangchainConfig(BaseModel):
+    try:
+        from langchain_community.vectorstores import VectorStore
+    except ImportError:
+        raise ImportError("The 'langchain_community' library is required. Please install it using 'pip install langchain_community'.")
+    VectorStore: ClassVar[type] = VectorStore
+
+    client: VectorStore = Field(description="Existing VectorStore instance")
+    collection_name: str = Field("mem0", description="Name of the collection to use")
+
+    @model_validator(mode="before")
+    @classmethod
+    def validate_extra_fields(cls, values: Dict[str, Any]) -> Dict[str, Any]:
+        allowed_fields = set(cls.model_fields.keys())
+        input_fields = set(values.keys())
+        extra_fields = input_fields - allowed_fields
+        if extra_fields:
+            raise ValueError(
+                f"Extra fields not allowed: {', '.join(extra_fields)}. Please input only the following fields: {', '.join(allowed_fields)}"
+            )
+        return values
+
+    model_config = {
+        "arbitrary_types_allowed": True,
+    }