[BUG]: Adding validation check for "chroma:document" in metadata. (#1718

)

Closes: #1717

## Description of changes

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
- Fixed an issue where if the metadata key is set to `chroma:document`
it is either ignore when inserting or overrides the actual document when
updating records by `id`

## Test plan
*How are these changes tested?*

- [x] Tests pass locally with `pytest` for python, `yarn test` for js

## Documentation Changes
N/A

chromadb/api/types.py

@@ -20,7 +20,7 @@
 
 # Re-export types from chromadb.types
 __all__ = ["Metadata", "Where", "WhereDocument", "UpdateCollectionMetadata"]
-
+META_KEY_CHROMA_DOCUMENT = "chroma:document"
 T = TypeVar("T")
 OneOrMany = Union[T, List[T]]
 
@@ -265,6 +265,10 @@ def validate_metadata(metadata: Metadata) -> Metadata:
     if len(metadata) == 0:
         raise ValueError(f"Expected metadata to be a non-empty dict, got {metadata}")
     for key, value in metadata.items():
+        if key == META_KEY_CHROMA_DOCUMENT:
+            raise ValueError(
+                f"Expected metadata to not contain the reserved key {META_KEY_CHROMA_DOCUMENT}"
+            )
         if not isinstance(key, str):
             raise TypeError(
                 f"Expected metadata key to be a str, got {key} which is a {type(key)}"
@@ -476,7 +480,7 @@ def validate_embeddings(embeddings: Embeddings) -> Embeddings:
         raise ValueError(
             f"Expected each embedding in the embeddings to be a list, got {embeddings}"
         )
-    for i,embedding in enumerate(embeddings):
+    for i, embedding in enumerate(embeddings):
         if len(embedding) == 0:
             raise ValueError(
                 f"Expected each embedding in the embeddings to be a non-empty list, got empty embedding at pos {i}"

chromadb/test/segment/test_metadata.py

@@ -3,6 +3,8 @@
 import tempfile
 import pytest
 from typing import Generator, List, Callable, Iterator, Dict, Optional, Union, Sequence
+
+from chromadb.api.types import validate_metadata
 from chromadb.config import System, Settings
 from chromadb.db.base import ParameterValue, get_sql
 from chromadb.db.impl.sqlite import SqliteDB
@@ -677,3 +679,10 @@ def test_delete_segment(
         res = cur.execute(sql, params)
         # assert that all FTS rows are gone
         assert len(res.fetchall()) == 0
+
+
+def test_metadata_validation_forbidden_key() -> None:
+    with pytest.raises(ValueError, match="chroma:document"):
+        validate_metadata(
+            {"chroma:document": "this is not the document you are looking for"}
+        )