Merge pull request #8 from bmsuisse/dev

expose get polars schema

deltalake2db/__init__.py

@@ -2,5 +2,5 @@
 from .duckdb import get_sql_for_delta_expr
 from .duckdb import create_view_for_delta as duckdb_create_view_for_delta
 from .duckdb import apply_storage_options as duckdb_apply_storage_options
-from .polars import scan_delta_union as polars_scan_delta
+from .polars import scan_delta_union as polars_scan_delta, get_polars_schema
 from .protocol_check import is_protocol_supported

deltalake2db/polars.py

@@ -8,6 +8,7 @@
     import polars as pl
 from deltalake import DeltaTable, Field, DataType
 from deltalake.schema import StructType, ArrayType, MapType
+from collections import OrderedDict
 import os
 
 
@@ -136,6 +137,20 @@ def _filter_cond(f: "pl.LazyFrame", conditions: dict) -> "pl.LazyFrame":
     return f.filter(**conditions)
 
 
+def get_polars_schema(
+    delta_table: Union[DeltaTable, Path, str],
+) -> "OrderedDict[str, pl.PolarsDataType]":
+    from .protocol_check import check_is_supported
+
+    if isinstance(delta_table, Path) or isinstance(delta_table, str):
+        delta_table = DeltaTable(delta_table)
+    check_is_supported(delta_table)
+    res_dict = OrderedDict()
+    for f in delta_table.schema().fields:
+        res_dict[f.name] = _get_type(f.type)
+    return res_dict
+
+
 def scan_delta_union(
     delta_table: Union[DeltaTable, Path, str],
     conditions: Optional[dict] = None,