Honor multiline JSON for BoxList string input and output

AUTHORS.rst

@@ -37,6 +37,7 @@ Code contributions:
 - Jesper Schlegel (jesperschlegel)
 - J vanBemmel (jbemmel)
 - m-janicki
+- shguild
 
 
 Suggestions and bug reporting:

CHANGES.rst

@@ -1,6 +1,11 @@
 Changelog
 =========
 
+Unreleased
+----------
+
+* Honor ``multiline=True`` for BoxList JSON string input and output, matching file behavior.
+
 Version 7.4.1
 -------------
 

box/box_list.py

@@ -210,14 +210,18 @@ def to_json(
         :param filename: If provided will save to file
         :param encoding: File encoding
         :param errors: How to handle encoding errors
-        :param multiline: Put each item in list onto it's own line
+        :param multiline: Put each item in list onto its own line, in a string or file
         :param json_kwargs: additional arguments to pass to json.dump(s)
         :return: string of JSON or return of `json.dump`
         """
-        if filename and multiline:
+        if multiline:
             lines = [_to_json(item, filename=None, encoding=encoding, errors=errors, **json_kwargs) for item in self]
-            with open(filename, "w", encoding=encoding, errors=errors) as f:
-                f.write("\n".join(lines))
+            text = "\n".join(lines)
+            if filename:
+                with open(filename, "w", encoding=encoding, errors=errors) as f:
+                    f.write(text)
+            else:
+                return text
         else:
             return _to_json(self.to_list(), filename=filename, encoding=encoding, errors=errors, **json_kwargs)
 
@@ -239,7 +243,7 @@ def from_json(
         :param filename: filename to open and pass to `json.load`
         :param encoding: File encoding
         :param errors: How to handle encoding errors
-        :param multiline: One object per line
+        :param multiline: One object per line, in a string or file
         :param kwargs: parameters to pass to `Box()` or `json.loads`
         :return: BoxList object from json data
         """

box/converters.py

@@ -182,8 +182,15 @@ def _from_json(
                 ]
             else:
                 data = json.load(f, **kwargs)
-    elif json_string:
-        data = json.loads(json_string, **kwargs)
+    elif json_string or (multiline and json_string is not None):
+        if multiline:
+            data = [
+                json.loads(line.strip(), **kwargs)
+                for line in StringIO(json_string, newline=None)
+                if line.strip() and not line.strip().startswith("#")
+            ]
+        else:
+            data = json.loads(json_string, **kwargs)
     else:
         raise BoxError("from_json requires a string or filename")
     return data

test/test_json_lines_strings.py

@@ -0,0 +1,63 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+import json
+
+import pytest
+
+from box import BoxList
+
+
+@pytest.mark.parametrize("data", [[], [{"a": 1}], [{"a": 1}, {"b": 2}], [None, False, 3, "café\u2028text"]])
+def test_multiline_string_output_matches_file(tmp_path, data):
+    values = BoxList(data)
+    path = tmp_path / "values.jsonl"
+    values.to_json(filename=path, multiline=True)
+
+    result = values.to_json(multiline=True)
+
+    assert result == path.read_text(encoding="utf-8")
+    assert result == "\n".join(json.dumps(value, ensure_ascii=False) for value in data)
+
+
+@pytest.mark.parametrize("newline", ["\n", "\r\n", "\r"])
+def test_multiline_string_input_matches_file(tmp_path, newline):
+    text = newline.join(["# comment", "", '{"FirstKey": 1}', "   ", ' {"SecondKey": "café\u2028text"} ', "# end"])
+    path = tmp_path / "values.jsonl"
+    path.write_bytes(text.encode("utf-8"))
+
+    result = BoxList.from_json(text, multiline=True, camel_killer_box=True)
+    from_file = BoxList.from_json(filename=path, multiline=True, camel_killer_box=True)
+
+    assert result == from_file
+    assert result[0].first_key == 1
+    assert result[1].second_key == "café\u2028text"
+
+
+@pytest.mark.parametrize("text", ["", "\n \r\n", "# comment\n  # another\n"])
+def test_empty_multiline_string_input(text):
+    assert BoxList.from_json(text, multiline=True) == []
+
+
+def test_multiline_string_json_options():
+    values = BoxList([{"b": 2, "a": 1}, {"c": 3}])
+    text = values.to_json(multiline=True, sort_keys=True, separators=(",", ":"))
+
+    assert text == '{"a":1,"b":2}\n{"c":3}'
+    assert BoxList.from_json(text, multiline=True, parse_int=str) == [{"a": "1", "b": "2"}, {"c": "3"}]
+
+
+@pytest.mark.parametrize("text", ['{"a": 1}\nnot json', '{"a": 1}\n{"b":'])
+def test_multiline_string_rejects_invalid_json(text):
+    with pytest.raises(json.JSONDecodeError):
+        BoxList.from_json(text, multiline=True)
+
+
+def test_multiple_objects_require_multiline():
+    with pytest.raises(json.JSONDecodeError):
+        BoxList.from_json('{"a": 1}\n{"b": 2}')
+
+
+def test_default_json_array_behavior():
+    values = BoxList([{"a": 1}, {"b": 2}])
+    assert json.loads(values.to_json()) == values.to_list()
+    assert BoxList.from_json(values.to_json()) == values