Label fix

docs/source/markup.rst

@@ -465,6 +465,32 @@ uses XML-friendly "-"-separated attribute names in markup.
        </fieldset>
      </form:with>
 
+   **Targeting Radio Buttons and Checkboxes:**
+
+   When working with radio buttons or checkboxes, each input element with a
+   different ``value=`` attribute gets a unique ``id`` by appending the value
+   to the base id (e.g., ``f_choice_a``, ``f_choice_b``).  To generate a
+   label that targets a specific radio button or checkbox, provide a
+   ``value=`` attribute on the label tag:
+
+   .. doctest:: transforms2
+
+     >>> from flatland import String
+     >>> from flatland.out.markup import Generator
+     >>> html = Generator(auto_domid=True, auto_for=True)
+     >>> choice = String.named('choice')('b')
+     >>> print(html.label(choice, value='a', contents='Option A'))
+     <label for="f_choice_a">Option A</label>
+     >>> print(html.input(choice, type='radio', value='a'))
+     <input type="radio" name="choice" value="a" id="f_choice_a" />
+     >>> print(html.label(choice, value='b', contents='Option B'))
+     <label for="f_choice_b">Option B</label>
+     >>> print(html.input(choice, type='radio', value='b'))
+     <input type="radio" name="choice" value="b" checked="checked" id="f_choice_b" />
+
+   The ``value=`` attribute is automatically removed from the rendered label
+   tag and is only used to generate the correct ``for=`` attribute.
+
 
 .. describe:: auto-tabindex
 

src/flatland/out/generic.py

@@ -201,15 +201,15 @@ def transform_domid(tagname, attributes, contents, context, bind):
 @defaults({"auto_for": False})
 def transform_for(tagname, attributes, contents, context, bind):
     proceed, forced = _pop_toggle("auto_for", attributes, context)
-    if not proceed or bind is None:
-        return contents
-
-    current = attributes.get("for")
-    if forced or current is None and tagname in _auto_tags["for"]:
-        raw_id = _generate_raw_domid(tagname, attributes, bind)
-        if raw_id:
-            fmt = context["domid_format"]
-            attributes["for"] = fmt % raw_id
+    if proceed and bind is not None:
+        current = attributes.get("for")
+        if forced or current is None and tagname in _auto_tags["for"]:
+            raw_id = _generate_raw_domid(tagname, attributes, bind)
+            if raw_id:
+                fmt = context["domid_format"]
+                attributes["for"] = fmt % raw_id
+    if tagname == "label":
+        attributes.pop("value", None)
     return contents
 
 
@@ -282,11 +282,17 @@ def _generate_raw_domid(tagname, attributes, bind):
     if not basis:
         return
 
+    suffix = None
     # add the value="" to CHECKBOX and RADIO to produce a unique ID
     if tagname == "input" and attributes.get("type") in ("checkbox", "radio"):
         suffix = _sanitize_domid_suffix(attributes.get("value", ""))
-        if suffix:
-            basis += "_" + suffix
+    # when the value attribute is supplied for a LABEL, add it to domid.
+    # this is used to produce LABELs with matching for="..." attribute values
+    # corresponding to input checkbox/radio IDs.
+    if tagname == "label":
+        suffix = _sanitize_domid_suffix(attributes.get("value", ""))
+    if suffix:
+        basis += "_" + suffix
     return basis
 
 

tests/markup/test_label_for_radio_checkbox.py

@@ -0,0 +1,155 @@
+"""Tests for label 'for' attribute generation with radio/checkbox inputs."""
+from flatland import String
+from flatland.out.markup import Generator
+
+import pytest
+
+
+@pytest.fixture
+def schema():
+    return String.named("choice")
+
+
+@pytest.fixture
+def html():
+    return Generator(markup="html", auto_domid=True, auto_for=True)
+
+
+@pytest.fixture
+def xml():
+    return Generator(markup="xml", auto_domid=True, auto_for=True)
+
+
+def test_complete_radio_form_example(schema, html):
+    """Test a complete example form."""
+    el = schema("b")
+
+    # Generate label for option 'a'
+    label_a = html.label(el, value="a", contents="Option A")
+    assert 'for="f_choice_a"' in label_a
+    assert 'Option A' in label_a
+    assert 'value="a"' not in label_a
+
+    # Generate radio input for option 'a'
+    input_a = html.input(el, type="radio", value="a")
+    assert 'id="f_choice_a"' in input_a
+    assert 'name="choice"' in input_a
+    assert 'type="radio"' in input_a
+    assert 'checked' not in input_a
+    assert 'value="a"' in input_a
+
+    # Generate label for option 'b'
+    label_b = html.label(el, value="b", contents="Option B")
+    assert 'for="f_choice_b"' in label_b
+    assert 'Option B' in label_b
+    assert 'value="b"' not in label_b
+
+    # Generate radio input for option 'b' (should be checked)
+    input_b = html.input(el, type="radio", value="b")
+    assert 'id="f_choice_b"' in input_b
+    assert 'name="choice"' in input_b
+    assert 'type="radio"' in input_b
+    assert 'checked="checked"' in input_b
+    assert 'value="b"' in input_b
+
+
+def test_label_without_value_backward_compatibility(schema, html):
+    """Test that labels without a value attribute still work as before."""
+    el = schema("b")
+
+    # Label without value should generate for="f_choice" (no suffix)
+    label = html.label(el)
+    assert 'for="f_choice"' in label
+    assert 'value=' not in label
+
+
+def test_label_with_empty_value(schema, html):
+    """Test that label with empty value doesn't add suffix."""
+    el = schema("test")
+
+    # Label with empty value should not add suffix
+    label = html.label(el, value="")
+    assert 'for="f_choice"' in label
+    assert 'value=' not in label
+
+
+def test_label_value_sanitization(schema, html):
+    """Test that label value is sanitized like input values."""
+    el = schema("test")
+
+    # Value with special characters should be sanitized
+    label = html.label(el, value="option-1")
+    assert 'for="f_choice_option-1"' in label
+
+    # Value with invalid characters should be sanitized
+    label2 = html.label(el, value="option@#$1")
+    # Invalid characters should be removed, leaving "option1"
+    assert 'for="f_choice_option1"' in label2
+
+
+def test_label_xml_format(schema, xml):
+    """Test that the label value attribute works with XML format."""
+    el = schema("b")
+
+    label = xml.label(el, value="a")
+    assert 'for="f_choice_a"' in label
+    assert 'value=' not in label
+
+    # Label is not a void element, so it has a closing tag
+    assert '</label>' in label
+
+
+def test_label_explicit_for_not_overridden(schema, html):
+    """Test that explicitly provided 'for' attribute is not overridden."""
+    el = schema("b")
+
+    # Explicit 'for' should take precedence
+    label = html.label(el, value="a", **{"for": "custom_id"})
+    assert 'for="custom_id"' in label
+    # Value should still be removed from attributes
+    assert 'value=' not in label
+
+
+def test_label_auto_for_disabled(schema):
+    """Test that the value attribute has no effect when auto_for is disabled."""
+    html = Generator(markup="html", auto_domid=True, auto_for=False)
+    el = schema("b")
+
+    # With auto_for=False, no 'for' attribute should be generated
+    label = html.label(el, value="a")
+    assert 'for=' not in label
+    # Value should still be removed
+    assert 'value=' not in label
+
+
+def test_label_with_contents_and_value(schema, html):
+    """Test that the label can have both contents and value attribute."""
+    el = schema("b")
+
+    label = html.label(el, value="a", contents="Option A")
+    assert 'for="f_choice_a"' in label
+    assert 'Option A' in label
+    assert 'value=' not in label
+
+
+def test_label_value_with_numbers(schema, html):
+    """Test that numeric values work correctly."""
+    el = schema("1")
+
+    label = html.label(el, value="1")
+    assert 'for="f_choice_1"' in label
+
+    label2 = html.label(el, value="123")
+    assert 'for="f_choice_123"' in label2
+
+
+def test_label_forced_auto_for_with_value(schema):
+    """Test that forced auto_for works with a value attribute."""
+    html = Generator(markup="html", auto_domid=True, auto_for=False)
+    el = schema("b")
+
+    # Force auto_for with auto_for="on"
+    label = html.label(el, value="a", auto_for="on")
+    assert 'for="f_choice_a"' in label
+    assert 'value=' not in label
+    assert 'auto_for=' not in label