diff --git a/tiled/_tests/adapters/test_arrow.py b/tiled/_tests/adapters/test_arrow.py
index 7515cb85b..24cf4b34a 100644
--- a/tiled/_tests/adapters/test_arrow.py
+++ b/tiled/_tests/adapters/test_arrow.py
@@ -4,7 +4,9 @@
 import pytest
 
 from tiled.adapters.arrow import ArrowAdapter
+from tiled.structures.core import StructureFamily
 from tiled.structures.table import TableStructure
+from tiled.structures.data_source import DataSource, Management, Storage
 
 names = ["f0", "f1", "f2"]
 data0 = [
@@ -26,11 +28,30 @@
 
 
 @pytest.fixture
-def adapter() -> ArrowAdapter:
+def data_source_from_init_storage() -> DataSource:
     table = pa.Table.from_arrays(data0, names)
     structure = TableStructure.from_arrow_table(table, npartitions=3)
-    assets = ArrowAdapter.init_storage(data_uri, structure=structure, path_parts=[])
-    return ArrowAdapter([asset.data_uri for asset in assets], structure=structure)
+    data_source = DataSource(
+        management=Management.writable,
+        mimetype="application/vnd.apache.arrow.file",
+        structure_family=StructureFamily.table,
+        structure=structure,
+        assets=[],
+    )
+    storage = Storage(filesystem=data_uri, sql=None)
+    return ArrowAdapter.init_storage(
+        data_source=data_source, storage=storage, path_parts=[]
+    )
+
+
+@pytest.fixture
+def adapter(data_source_from_init_storage: DataSource) -> ArrowAdapter:
+    data_source = data_source_from_init_storage
+    return ArrowAdapter(
+        [asset.data_uri for asset in data_source.assets],
+        data_source.structure,
+    )
+
 
 
 def test_attributes(adapter: ArrowAdapter) -> None:
diff --git a/tiled/_tests/test_catalog.py b/tiled/_tests/test_catalog.py
index a4c915ec0..1af24c1f2 100644
--- a/tiled/_tests/test_catalog.py
+++ b/tiled/_tests/test_catalog.py
@@ -268,7 +268,7 @@ async def test_write_dataframe_external_direct(a, tmpdir):
 async def test_write_array_internal_direct(a, tmpdir):
     arr = numpy.ones((5, 3))
     ad = ArrayAdapter.from_array(arr)
-    structure = asdict(ad.structure())
+    structure = ad.structure()
     await a.create_node(
         key="x",
         structure_family="array",
@@ -521,7 +521,7 @@ async def test_constraints_on_parameter_and_num(a, assets):
                 DataSource(
                     structure_family=arr_adapter.structure_family,
                     mimetype="text/csv",
-                    structure=asdict(arr_adapter.structure()),
+                    structure=arr_adapter.structure(),
                     parameters={},
                     management=Management.external,
                     assets=assets,
diff --git a/tiled/adapters/arrow.py b/tiled/adapters/arrow.py
index 08ab7aa4c..eed744f79 100644
--- a/tiled/adapters/arrow.py
+++ b/tiled/adapters/arrow.py
@@ -70,9 +70,9 @@ def init_storage(
         Class to initialize the list of assets for given uri.
         Parameters
         ----------
-        data_uri :
-        structure :
-
+        storage : the storage option for .arrow files
+        data_source : data source representing the adapter
+        path_parts: the list of partitions
         Returns
         -------
         The list of assets.
@@ -81,6 +81,7 @@ def init_storage(
         data_uri = str(storage.get("filesystem")) + "".join(
             f"/{quote_plus(segment)}" for segment in path_parts
         )
+        print('uri', data_uri)
         directory = path_from_uri(data_uri)
         directory.mkdir(parents=True, exist_ok=True)
         assets = [
diff --git a/tiled/adapters/sql.py b/tiled/adapters/sql.py
index b57b5659b..b1cf5a93a 100644
--- a/tiled/adapters/sql.py
+++ b/tiled/adapters/sql.py
@@ -88,7 +88,7 @@ def init_storage(
         ----------
         storage: the storage kind
         data_source : data source describing the data
-        path_parts: ?
+        path_parts: the list of partitions.
         Returns
         -------
         A modified copy of the data source
diff --git a/tiled/adapters/zarr.py b/tiled/adapters/zarr.py
index b92e1d50e..3459606aa 100644
--- a/tiled/adapters/zarr.py
+++ b/tiled/adapters/zarr.py
@@ -13,9 +13,10 @@
 
 from ..adapters.utils import IndexersMixin
 from ..iterviews import ItemsView, KeysView, ValuesView
+from ..server.schemas import DataSource
 from ..structures.array import ArrayStructure
 from ..structures.core import Spec, StructureFamily
-from ..structures.data_source import Asset, DataSource, Storage
+from ..structures.data_source import Asset, Storage
 from ..type_aliases import JSON, NDSlice
 from ..utils import Conflicts, node_repr, path_from_uri
 from .array import ArrayAdapter, slice_and_shape_from_block_and_chunks
diff --git a/tiled/catalog/adapter.py b/tiled/catalog/adapter.py
index 93c7fd836..aebad928e 100644
--- a/tiled/catalog/adapter.py
+++ b/tiled/catalog/adapter.py
@@ -1192,6 +1192,10 @@ def _prepare_structure(structure_family, structure):
     "Convert from pydantic model to dict."
     if structure is None:
         return None
+    if isinstance(structure, dict):
+        return structure
+    if dataclasses.is_dataclass(structure):
+        return dataclasses.asdict(structure)
     return structure.model_dump()
 
 
diff --git a/tiled/server/schemas.py b/tiled/server/schemas.py
index 7c9dc3d66..67f449d02 100644
--- a/tiled/server/schemas.py
+++ b/tiled/server/schemas.py
@@ -149,10 +149,10 @@ def from_orm(cls, orm: tiled.catalog.orm.Revision) -> Revision:
 
 
 class DataSource(pydantic.BaseModel, Generic[StructureT]):
-    id: Optional[int]
+    id: Optional[int] = None
     structure_family: StructureFamily
     structure: Optional[StructureT]
-    mimetype: Optional[str]
+    mimetype: Optional[str] = None
     parameters: dict = {}
     assets: List[Asset] = []
     management: Management = Management.writable