Check the types when writing (#313)

pyiceberg/table/__init__.py

@@ -932,6 +932,14 @@ def append(self, df: pa.Table) -> None:
         Args:
             df: The Arrow dataframe that will be appended to overwrite the table
         """
+        try:
+            import pyarrow as pa
+        except ModuleNotFoundError as e:
+            raise ModuleNotFoundError("For writes PyArrow needs to be installed") from e
+
+        if not isinstance(df, pa.Table):
+            raise ValueError(f"Expected PyArrow table, got: {df}")
+
         if len(self.spec().fields) > 0:
             raise ValueError("Cannot write to partitioned tables")
 
@@ -954,6 +962,14 @@ def overwrite(self, df: pa.Table, overwrite_filter: BooleanExpression = ALWAYS_T
             overwrite_filter: ALWAYS_TRUE when you overwrite all the data,
                               or a boolean expression in case of a partial overwrite
         """
+        try:
+            import pyarrow as pa
+        except ModuleNotFoundError as e:
+            raise ModuleNotFoundError("For writes PyArrow needs to be installed") from e
+
+        if not isinstance(df, pa.Table):
+            raise ValueError(f"Expected PyArrow table, got: {df}")
+
         if overwrite_filter != AlwaysTrue():
             raise NotImplementedError("Cannot overwrite a subset of a table")
 

tests/integration/test_writes.py

@@ -391,3 +391,21 @@ def test_data_files(spark: SparkSession, session_catalog: Catalog, arrow_table_w
     assert [row.added_data_files_count for row in rows] == [1, 1, 0, 1, 1]
     assert [row.existing_data_files_count for row in rows] == [0, 0, 0, 0, 0]
     assert [row.deleted_data_files_count for row in rows] == [0, 0, 1, 0, 0]
+
+
+@pytest.mark.integration
+def test_invalid_arguments(spark: SparkSession, session_catalog: Catalog, arrow_table_with_null: pa.Table) -> None:
+    identifier = "default.arrow_data_files"
+
+    try:
+        session_catalog.drop_table(identifier=identifier)
+    except NoSuchTableError:
+        pass
+
+    tbl = session_catalog.create_table(identifier=identifier, schema=TABLE_SCHEMA, properties={'format-version': '1'})
+
+    with pytest.raises(ValueError, match="Expected PyArrow table, got: not a df"):
+        tbl.overwrite("not a df")
+
+    with pytest.raises(ValueError, match="Expected PyArrow table, got: not a df"):
+        tbl.append("not a df")