fix: let dataclass fields be documented with either Attributes or Parameters, without duplication

great_docs/_renderer/_render/docclass.py

@@ -71,7 +71,16 @@ def attribute_member_pages(self) -> list[layout.MemberPage]:
     def docstring_sections_content(self):
         items = super().docstring_sections_content
         titles = set(item[0] for item in items)
-        if not self.is_dataclass or "Parameters" in titles or not len(self.parameters):
+        # When the author documents the fields themselves (via either a
+        # `Parameters` or an `Attributes` docstring section), don't also
+        # synthesize a "Parameter Attributes" section — that would duplicate the
+        # same fields. Which of the two sections to use is left to the docs writer.
+        if (
+            not self.is_dataclass
+            or "Parameters" in titles
+            or "Attributes" in titles
+            or not len(self.parameters)
+        ):
             return items
 
         # Create and insert Parameter Attributes

test-packages/synthetic/specs/gdtest_dataclasses.py

@@ -2,12 +2,15 @@
 gdtest_dataclasses — @dataclass objects.
 
 Dimensions: A1, B1, C5, D1, E6, F6, G1, H7
-Focus: 3 dataclasses: one with default_factory, one frozen, one that also
-       defines methods. Tests dataclass field documentation, __init__
-       generation, and that a dataclass which defines methods still renders its
-       constructor signature (regression: `Class.overloads` is a dict keyed by
-       member name, so any class with methods was rendered through the overload
-       path and lost its constructor parameters).
+Focus: 3 dataclasses: one with default_factory, one frozen (documented with an
+       `Attributes` section), one that also defines methods. Tests dataclass
+       field documentation, __init__ generation, that fields documented under
+       either a `Parameters` or an `Attributes` section render once (no
+       duplicated "Parameter Attributes"), and that a dataclass which defines
+       methods still renders its constructor signature (regression:
+       `Class.overloads` is a dict keyed by member name, so any class with
+       methods was rendered through the overload path and lost its constructor
+       parameters).
 """
 
 SPEC = {
@@ -62,7 +65,10 @@ class Record:
                 """
                 An immutable data record.
 
-                Parameters
+                Documented with an ``Attributes`` section (rather than
+                ``Parameters``) to exercise that rendering path.
+
+                Attributes
                 ----------
                 id
                     Unique record identifier.

tests/renderer/test_classes.py

@@ -142,3 +142,66 @@ class Widget:
     qmd = render_code_variable(code, "Widget")
 
     assert "Widget(name, size=1)" in qmd
+
+
+def test_dataclass_attributes_section_not_duplicated():
+    """A dataclass documented with an `Attributes` section renders that section
+    once, without a synthesized "Parameter Attributes" duplicate.
+
+    The author may document a dataclass's fields with either a `Parameters` or
+    an `Attributes` section; great-docs must not also auto-generate a
+    "Parameter Attributes" section listing the same fields.
+    """
+    code = '''
+    from dataclasses import dataclass
+
+    @dataclass
+    class Widget:
+        """A widget.
+
+        Attributes
+        ----------
+        name
+            The widget name.
+        size
+            The widget size.
+        """
+
+        name: str
+        size: int = 1
+    '''
+    qmd = render_code_variable(code, "Widget")
+
+    assert "## Attributes {.doc-attributes}" in qmd
+    assert "## Parameter Attributes {.doc-parameter-attributes}" not in qmd
+    # The author's descriptions must be preserved.
+    assert "The widget name." in qmd
+
+
+def test_dataclass_parameters_section_not_duplicated():
+    """A dataclass documented with a `Parameters` section renders that section
+    once, without a synthesized "Parameter Attributes" duplicate.
+    """
+    code = '''
+    from dataclasses import dataclass
+
+    @dataclass
+    class Widget:
+        """A widget.
+
+        Parameters
+        ----------
+        name
+            The widget name.
+        size
+            The widget size.
+        """
+
+        name: str
+        size: int = 1
+    '''
+    qmd = render_code_variable(code, "Widget")
+
+    assert "## Parameters {.doc-parameters}" in qmd
+    assert "## Parameter Attributes {.doc-parameter-attributes}" not in qmd
+    assert "The widget name." in qmd

tests/test_gdg_rendered.py

@@ -974,6 +974,37 @@ def test_dataclass_with_methods_signature_has_fields():
     )
 
 
+@pytest.mark.dedicated
+@requires_bs4
+def test_dataclass_attributes_section_not_duplicated():
+    """A dataclass documented with an `Attributes` section renders it once,
+    without a synthesized "Parameter Attributes" duplicate.
+
+    Fields may be documented with either a `Parameters` or an `Attributes`
+    section; great-docs must not also auto-generate a "Parameter Attributes"
+    section listing the same fields. (`Record` in this package uses an
+    `Attributes` section.)
+    """
+    pkg = "gdtest_dataclasses"
+    if not _has_rendered_site(pkg):
+        pytest.skip("gdtest_dataclasses not rendered")
+
+    ref = _ref_dir(pkg)
+    page = ref / "Record.html"
+    if not page.exists():
+        pytest.skip("Record.html not found")
+
+    soup = _load_html(page)
+
+    assert soup.select_one("section.doc-attributes") is not None, (
+        "Record.html: expected an Attributes section"
+    )
+    assert soup.select_one("section.doc-parameter-attributes") is None, (
+        "Record.html: 'Attributes'-documented dataclass should not also render a "
+        "synthesized 'Parameter Attributes' section"
+    )
+
+
 @pytest.mark.dedicated
 @requires_bs4
 def test_async_functions_have_badge():