[table] Improve column name support

Use __set_name__ instead of explicitly passing name to .cell(), and use self.attribute if present.

src/bootlace/table/base.py

@@ -30,10 +30,19 @@ def __tag__(self) -> tags.html_tag:
 @attrs.define
 class ColumnBase(ABC):
     heading: Heading = attrs.field(converter=maybe(Heading))  # type: ignore
-    attribute: str | None = None
+    _attribute: str | None = None
+
+    def __set_name__(self, owner: type, name: str) -> None:
+        self._attribute = self._attribute or name
+
+    @property
+    def attribute(self) -> str:
+        if self._attribute is None:
+            raise ValueError("column must be named in Table or attribute= parameter must be provided")
+        return self._attribute
 
     @abstractmethod
-    def cell(self, name: str, value: Any) -> tags.html_tag:
+    def cell(self, value: Any) -> tags.html_tag:
         raise NotImplementedError("Subclasses must implement this method")
 
 
@@ -106,8 +115,8 @@ def render(self, items: list[Any]) -> tags.html_tag:
         for item in items:
             id = getattr(item, "id", None)
             tr = tags.tr(id=f"item-{id}" if id else None)
-            for column_name, column in self.columns.items():
-                td = column.cell(column_name, item)
+            for column in self.columns.values():
+                td = column.cell(item)
                 tr.add(td)
             tbody.add(tr)
         table.add(tbody)

src/bootlace/table/columns.py

@@ -12,17 +12,17 @@
 @attrs.define
 class Column(ColumnBase):
 
-    def cell(self, name: str, value: Any) -> tags.html_tag:
-        return tags.td(getattr(value, name))
+    def cell(self, value: Any) -> tags.html_tag:
+        return tags.td(getattr(value, self.attribute))
 
 
 @attrs.define
 class EditColumn(ColumnBase):
     endpoint: str = attrs.field(default=".edit")
 
-    def cell(self, name: str, value: Any) -> tags.html_tag:
+    def cell(self, value: Any) -> tags.html_tag:
         id = getattr(value, "id", None)
-        return tags.td(tags.a(getattr(value, name), href=url_for(self.endpoint, id=id)))
+        return tags.td(tags.a(getattr(value, self.attribute), href=url_for(self.endpoint, id=id)))
 
 
 @attrs.define
@@ -31,14 +31,14 @@ class CheckColumn(ColumnBase):
     yes: Icon = attrs.field(default=Icon("check", width=16, height=16))
     no: Icon = attrs.field(default=Icon("x", width=16, height=16))
 
-    def cell(self, name: str, value: Any) -> tags.html_tag:
-        if getattr(value, name):
+    def cell(self, value: Any) -> tags.html_tag:
+        if getattr(value, self.attribute):
             return tags.td(as_tag(self.yes))
         return tags.td(as_tag(self.no))
 
 
 @attrs.define
 class Datetime(ColumnBase):
 
-    def cell(self, name: str, value: Any) -> tags.html_tag:
-        return tags.td(getattr(value, name).isoformat())
+    def cell(self, value: Any) -> tags.html_tag:
+        return tags.td(getattr(value, self.attribute).isoformat())

tests/table/test_columns.py

@@ -24,6 +24,14 @@ class Item:
     when: dt.datetime = dt.datetime(2021, 1, 1, 12, 18, 5)
 
 
+def test_unnamed_column() -> None:
+
+    col = EditColumn(heading="Edit", endpoint="index")
+
+    with pytest.raises(ValueError):
+        col.attribute
+
+
 @pytest.mark.usefixtures("homepage")
 def test_edit_column(app: Flask) -> None:
 
@@ -34,7 +42,7 @@ def test_edit_column(app: Flask) -> None:
     assert str(th) == "<span>Edit</span>"
 
     with app.test_request_context("/"):
-        td = col.cell("editor", Item())
+        td = col.cell(Item())
 
     expected = '<td><a href="/?id=1">editor</a></td>'
 
@@ -46,7 +54,7 @@ def test_check_column(app: Flask) -> None:
     col = CheckColumn(heading="Check", attribute="check")
 
     with app.test_request_context("/"):
-        td = col.cell("check", Item())
+        td = col.cell(Item())
 
     expected = f"""
     <td>
@@ -56,7 +64,7 @@ def test_check_column(app: Flask) -> None:
     </td>"""
 
     with app.test_request_context("/"):
-        td = col.cell("check", Item(check=False))
+        td = col.cell(Item(check=False))
 
     expected = f"""
     <td>
@@ -84,7 +92,7 @@ def test_datetime_column(app: Flask) -> None:
 
     assert_same_html(expected_heading, str(th))
 
-    td = col.cell("when", Item())
+    td = col.cell(Item())
 
     expected = "<td>2021-01-01T12:18:05</td>"