Fix serialization for lists of dicts in YAML

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Added support for Python 3.10's builtin optional types (e.g. `int | None`).
 - Fixed handling of commented blocks in YAML files.
+- Fixed serialization for `list` of `dict` in YAML.
 
 # 1.0 (2021-10-04)
 

datafiles/formats.py

@@ -5,7 +5,7 @@
 from contextlib import suppress
 from io import StringIO
 from pathlib import Path
-from typing import IO, Dict, List
+from typing import IO, Dict, List, Union
 
 import log
 
@@ -105,7 +105,10 @@ def serialize(cls, data):
 
         stream = StringIO()
         yaml.dump(data, stream)
-        text = stream.getvalue().strip() + '\n'
+        text = stream.getvalue()
+
+        if text.startswith('  '):
+            return text[2:].replace('\n  ', '\n')
 
         if text == "{}\n":
             return ""
@@ -127,7 +130,9 @@ def deserialize(path: Path, extension: str, *, formatter=None) -> Dict:
         return data
 
 
-def serialize(data: Dict, extension: str = '.yml', *, formatter=None) -> str:
+def serialize(
+    data: Union[Dict, List], extension: str = '.yml', *, formatter=None
+) -> str:
     if formatter is None:
         formatter = _get_formatter(extension)
     return formatter.serialize(data)

datafiles/tests/test_formats.py

@@ -30,6 +30,16 @@ def it_indents_blocks_by_default(expect, data):
             """
             )
 
+        def it_handles_lists_of_dicts(expect):
+            data = [{"one": 1, "two": 2}]
+            text = formats.serialize(data, '.yaml')
+            expect(text) == dedent(
+                """
+            - one: 1
+              two: 2
+            """
+            )
+
 
 def describe_deserialize():
     @pytest.fixture

pyproject.toml

@@ -1,7 +1,7 @@
 [tool.poetry]
 
 name = "datafiles"
-version = "1.1b2"
+version = "1.1b3"
 description = "File-based ORM for dataclasses."
 
 license = "MIT"
@@ -44,7 +44,7 @@ classifiers = [
 python = "^3.7"
 
 # Formats
-"ruamel.yaml" = "^0.17.17"
+"ruamel.yaml" = "^0.17.20"
 tomlkit = "^0.7.2"
 
 # ORM