fix: use Document.from_dict in InMemoryDocumentStore.load_from_disk

haystack/document_stores/in_memory/document_store.py

@@ -403,7 +403,7 @@ def load_from_disk(cls, path: str) -> "InMemoryDocumentStore":
             documents = data.pop("documents")
             cls_object = default_from_dict(cls, data)
             cls_object.write_documents(
-                documents=[Document(**doc) for doc in documents], policy=DuplicatePolicy.OVERWRITE
+                documents=[Document.from_dict(doc) for doc in documents], policy=DuplicatePolicy.OVERWRITE
             )
             return cls_object
 

releasenotes/notes/fix-load-from-disk-document-from-dict-5b8d8943b6c7867d.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixed ``InMemoryDocumentStore.load_from_disk`` reconstructing documents with the plain
+    ``Document`` constructor instead of ``Document.from_dict``. Documents containing a ``blob``
+    (``ByteStream``) or a ``sparse_embedding`` (``SparseEmbedding``) were loaded with those fields
+    as raw dictionaries, which later crashed ``repr()``, ``to_dict()``, equality comparison,
+    ``save_to_disk`` of the reloaded store, and any component accessing ``document.blob.data``.

test/document_stores/test_in_memory.py

@@ -13,6 +13,7 @@
 import pytest
 
 from haystack import Document
+from haystack.dataclasses import ByteStream, SparseEmbedding
 from haystack.document_stores.errors import DocumentStoreError, DuplicateDocumentError
 from haystack.document_stores.in_memory import InMemoryDocumentStore
 from haystack.testing.document_store import (
@@ -146,6 +147,26 @@ def test_save_to_disk_and_load_from_disk(self, in_memory_doc_store: InMemoryDocu
         assert list(document_store_loaded.storage.values()) == docs
         assert document_store_loaded.to_dict() == in_memory_doc_store.to_dict()
 
+    def test_save_to_disk_and_load_from_disk_with_blob_and_sparse_embedding(
+        self, in_memory_doc_store: InMemoryDocumentStore, tmp_dir: str
+    ) -> None:
+        doc = Document(
+            content="document with binary data",
+            blob=ByteStream(data=b"binary data", mime_type="image/png"),
+            sparse_embedding=SparseEmbedding(indices=[0, 5], values=[0.1, 0.9]),
+        )
+        in_memory_doc_store.write_documents([doc])
+        save_path = tmp_dir + "/in_memory_doc_store.json"
+        in_memory_doc_store.save_to_disk(save_path)
+        document_store_loaded = InMemoryDocumentStore.load_from_disk(save_path)
+
+        loaded_doc = document_store_loaded.filter_documents()[0]
+        assert isinstance(loaded_doc.blob, ByteStream)
+        assert isinstance(loaded_doc.sparse_embedding, SparseEmbedding)
+        assert loaded_doc == doc
+        # The loaded store must be savable again
+        document_store_loaded.save_to_disk(save_path)
+
     def test_invalid_bm25_algorithm(self):
         with pytest.raises(ValueError, match="BM25 algorithm 'invalid' is not supported"):
             InMemoryDocumentStore(bm25_algorithm="invalid")  # type: ignore[arg-type]