Merge pull request #60 from volfpeter/feat/complex-value-formatting

feat: add support for complex values to Formatter, fixes #59

Author: volfpeter

README.md

@@ -266,6 +266,7 @@ These are default tag attribute formatting rules:
 - `bool` attribute values are converted to strings (`"true"` and `"false"`).
 - `XBool.true` attributes values are converted to an empty string, and `XBool.false` values are skipped (only the attribute name is rendered).
 - `date` and `datetime` attribute values are converted to ISO strings.
+- Complex values such as lists, dictionaries, tuples, and sets are JSON serialized.
 
 ### Error boundary
 

docs/index.md

@@ -266,6 +266,7 @@ These are default tag attribute formatting rules:
 - `bool` attribute values are converted to strings (`"true"` and `"false"`).
 - `XBool.true` attributes values are converted to an empty string, and `XBool.false` values are skipped (only the attribute name is rendered).
 - `date` and `datetime` attribute values are converted to ISO strings.
+- Complex values such as lists, dictionaries, tuples, and sets are JSON serialized.
 
 ### Error boundary
 

htmy/core.py

@@ -2,6 +2,7 @@
 
 import abc
 import enum
+import json
 from collections.abc import Callable, Container
 from typing import TYPE_CHECKING, Any, ClassVar, TypedDict, cast
 from xml.sax.saxutils import escape as xml_escape
@@ -251,14 +252,17 @@ class Formatter(ContextAware):
     """
     The default, context-aware property name and value formatter.
 
+    The formatter supports both primitive and (many) complex values, such as lists,
+    dictionaries, tuples, and sets. Complex values are JSON-serialized by default.
+
     Important: the default implementation looks up the formatter for a given value by checking
     its type, but it doesn't do this check with the base classes of the encountered type. For
     example the formatter will know how to format `datetime` object, but it won't know how to
     format a `MyCustomDatetime(datetime)` instance.
 
     One reason for this is efficiency: always checking the base classes of every single value is a
     lot of unnecessary calculation. The other reason is customizability: this way you could use
-    subclassing for fomatter selection, e.g. with `LocaleDatetime(datetime)`-like classes.
+    subclassing for formatter selection, e.g. with `LocaleDatetime(datetime)`-like classes.
 
     Property name and value formatters may raise a `SkipProperty` error if a property should be skipped.
     """
@@ -337,6 +341,10 @@ def _base_formatters(self) -> dict[type, Callable[[Any], str]]:
             bool: lambda v: "true" if v else "false",
             date: lambda d: cast(date, d).isoformat(),
             datetime: lambda d: cast(datetime, d).isoformat(),
+            dict: lambda v: json.dumps(v),
+            list: lambda v: json.dumps(v),
+            tuple: lambda v: json.dumps(v),
+            set: lambda v: json.dumps(tuple(v)),
             XBool: lambda v: cast(XBool, v).format(),
             type(None): SkipProperty.format_property,
         }

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "htmy"
-version = "0.7.1"
+version = "0.7.2"
 description = "Async, pure-Python rendering engine."
 authors = ["Peter Volf <do.volfp@gmail.com>"]
 license = "MIT"
@@ -14,7 +14,7 @@ markdown = "^3.7"
 
 [tool.poetry.group.dev.dependencies]
 mkdocs-material = "^9.5.39"
-mkdocstrings = {extras = ["python"], version = "^0.26.1"}
+mkdocstrings = { extras = ["python"], version = "^0.26.1" }
 mypy = "^1.15.0"
 poethepoet = "^0.29.0"
 pytest = "^8.3.3"
@@ -49,17 +49,17 @@ exclude = [
     "docs",
 ]
 lint.select = [
-    "B",  # flake8-bugbear
-    "C",  # flake8-comprehensions
-    "E",  # pycodestyle errors
-    "F",  # pyflakes
-    "I",  # isort
-    "S",  # flake8-bandit - we must ignore these rules in tests
-    "W",  # pycodestyle warnings
+    "B", # flake8-bugbear
+    "C", # flake8-comprehensions
+    "E", # pycodestyle errors
+    "F", # pyflakes
+    "I", # isort
+    "S", # flake8-bandit - we must ignore these rules in tests
+    "W", # pycodestyle warnings
 ]
 
 [tool.ruff.lint.per-file-ignores]
-"tests/**/*" = ["S101"]  # S101: use of assert detected
+"tests/**/*" = ["S101"] # S101: use of assert detected
 
 [tool.poe.tasks]
 check-format = "ruff format --check ."
@@ -70,4 +70,4 @@ mypy = "mypy ."
 test = "python -m pytest tests"
 static-checks.sequence = ["lint", "check-format", "mypy"]
 static-checks.ignore_fail = "return_non_zero"
-serve-docs = "mkdocs serve"
+serve-docs = "mkdocs serve"

tests/test_formatter.py

@@ -0,0 +1,50 @@
+from typing import Any
+
+import pytest
+
+from htmy import Formatter
+
+
+@pytest.fixture
+def formatter() -> Formatter:
+    return Formatter()
+
+
+@pytest.mark.parametrize(
+    ("data", "formatted_value"),
+    (
+        ({}, "{}"),
+        ([], "[]"),
+        ((), "[]"),
+        (set(), "[]"),
+        (
+            {"drink": "coffee", "food": "pizza", "bill": {"net": 100, "vat": 20, "total": 120}},
+            '{"drink": "coffee", "food": "pizza", "bill": {"net": 100, "vat": 20, "total": 120}}',
+        ),
+        (["string", 3.14, {"key": "value"}], '["string", 3.14, {"key": "value"}]'),
+        (("string", 3.14, {"key": "value"}), '["string", 3.14, {"key": "value"}]'),
+        ({"c0ff33"}, '["c0ff33"]'),
+    ),
+)
+def test_complex_value_formatting(data: Any, formatted_value: str, formatter: Formatter) -> None:
+    assert formatter.format_value(data) == formatted_value
+
+
+@pytest.mark.parametrize(
+    ("data", "formatted_value"),
+    (
+        ({}, '"{}"'),
+        ([], '"[]"'),
+        ((), '"[]"'),
+        (set(), '"[]"'),
+        (
+            {"drink": "coffee", "food": "pizza", "bill": {"net": 100, "vat": 20, "total": 120}},
+            '\'{"drink": "coffee", "food": "pizza", "bill": {"net": 100, "vat": 20, "total": 120}}\'',
+        ),
+        (["string", 3.14, {"key": "value"}], '\'["string", 3.14, {"key": "value"}]\''),
+        (("string", 3.14, {"key": "value"}), '\'["string", 3.14, {"key": "value"}]\''),
+        ({"c0ff33"}, "'[\"c0ff33\"]'"),
+    ),
+)
+def test_complex_property_formatting(data: Any, formatted_value: str, formatter: Formatter) -> None:
+    assert formatter.format("property", data) == f"property={formatted_value}"