BUG: Fix empty Data frames to JSON round-trippable back to data frames (#21318)

Author: Pyry Kovanen

doc/source/whatsnew/v0.23.1.txt

@@ -122,6 +122,7 @@ Bug Fixes
 - Bug in IO methods specifying ``compression='zip'`` which produced uncompressed zip archives (:issue:`17778`, :issue:`21144`)
 - Bug in :meth:`DataFrame.to_stata` which prevented exporting DataFrames to buffers and most file-like objects (:issue:`21041`)
 - Bug in :meth:`read_stata` and :class:`StataReader` which did not correctly decode utf-8 strings on Python 3 from Stata 14 files (dta version 118) (:issue:`21244`)
+- Bug in IO JSON :func:`read_json` reading empty JSON schema with ``orient='table'`` back to :class:`DataFrame` caused an error (:issue:`21287`)
 
 **Reshaping**
 

pandas/io/json/table_schema.py

@@ -296,7 +296,7 @@ def parse_table_schema(json, precise_float):
     """
     table = loads(json, precise_float=precise_float)
     col_order = [field['name'] for field in table['schema']['fields']]
-    df = DataFrame(table['data'])[col_order]
+    df = DataFrame(table['data'], columns=col_order)[col_order]
 
     dtypes = {field['name']: convert_json_field_to_pandas_type(field)
               for field in table['schema']['fields']}

pandas/tests/io/json/test_json_table_schema.py

@@ -560,3 +560,16 @@ def test_multiindex(self, index_names):
         out = df.to_json(orient="table")
         result = pd.read_json(out, orient="table")
         tm.assert_frame_equal(df, result)
+
+    @pytest.mark.parametrize("strict_check", [
+        pytest.param(True, marks=pytest.mark.xfail), False])
+    def test_empty_frame_roundtrip(self, strict_check):
+        # GH 21287
+        df = pd.DataFrame([], columns=['a', 'b', 'c'])
+        expected = df.copy()
+        out = df.to_json(orient='table')
+        result = pd.read_json(out, orient='table')
+        # TODO: When DF coercion issue (#21345) is resolved tighten type checks
+        tm.assert_frame_equal(expected, result,
+                              check_dtype=strict_check,
+                              check_index_type=strict_check)