feat: dict choices shortcut for datalists

Author: azmeuk

CHANGES.rst

@@ -1,5 +1,13 @@
 .. currentmodule:: wtforms
 
+Version 3.3.0b4
+---------------
+
+Unreleased
+
+- :class:`~datalist.DataList` ``choices`` accepts the shorthand
+  ``{value: label}`` dict syntax. :issue:`886`
+
 Version 3.3.0b3
 ---------------
 

docs/fields.rst

@@ -610,7 +610,8 @@ Data Lists
 
     ``choices`` is either a list of :class:`~wtforms.DataListChoice`
     (or plain strings, in which case the string is used as both value
-    and label), or a callable invoked at render time. The callable
+    and label), a shorthand ``{value: label}`` dict, or a callable
+    invoked at render time. The callable
     may take no argument (``fn()``) for a static list, or ``(field)``
     to adapt the suggestions to the current field value at each
     render — convenient for server-side filtering::

src/wtforms/datalist.py

@@ -121,6 +121,10 @@ def iter_choices(self, field=None):
         raw = self._choices
         if raw is None:
             return []
+        if isinstance(raw, dict):
+            return [
+                DataListChoice(value=value, label=label) for value, label in raw.items()
+            ]
         return [DataListChoice.from_input(item) for item in raw]
 
     def __call__(self, field=None, **kwargs):

tests/test_datalist.py

@@ -48,6 +48,21 @@ def test_choice_choices_render_value_and_label():
     assert 'label="United States"' in html
 
 
+def test_dict_shorthand_choices_render_value_and_label():
+    """A ``{value: label}`` dict renders both ``value=`` and ``label=`` attributes."""
+
+    class F(Form):
+        country = StringField(
+            datalist=DataList({"FR": "France", "US": "United States"})
+        )
+
+    html = str(F().country.datalist())
+    assert 'value="FR"' in html
+    assert 'label="France"' in html
+    assert 'value="US"' in html
+    assert 'label="United States"' in html
+
+
 @pytest.mark.parametrize(
     ("postdata", "expected"),
     [