In WTForms, SelectFieldBase (which wtforms.SelectField inherits from) defines __iter__() to yield "_Option" instances - _Option is a Field subclass defined within SelectFieldBase to hold the options for the SelectField. To fill these _Option instances, __iter__() calls self.iter_choices, which it expects will yield a 3-tuple of (value, label, checked), where "checked" is a simple boolean indicating if the current field data value is equal to the option value, and so should be rendered as the currently selected option in the popup. This value is assigned into the _Option.checked attribute.
wtforms-components redefines the "iter_choices()" method, so that the third item of the 3-tuple it yields is not the simple boolean, but a 2-tuple with a coerce function and a data value, which is what __iter__() will now see. Internally wtforms handles this change since its widget knows about the revised output of iter_choices(). But the original WTForms __iter__() method doesn't, and assigns a bogus value to the "checked" attribute of the _Option instances it spits out.
Should wtforms-components have re-implemented SelectField.__iter__() so that it provides valid _Option fields if you iterate the SelectField? Perhaps there is no legitmate use for iterating through the options of a SelectField like this, but I was using it to add HTML "data-" attributes on the individual "option" items, and got bit by this - all options come out with the HTML "selected" attribute set.
In WTForms, SelectFieldBase (which wtforms.SelectField inherits from) defines
__iter__()to yield"_Option"instances -_Optionis a Field subclass defined within SelectFieldBase to hold the options for the SelectField. To fill these_Optioninstances,__iter__()calls self.iter_choices, which it expects will yield a 3-tuple of (value, label, checked), where "checked" is a simple boolean indicating if the current field data value is equal to the option value, and so should be rendered as the currently selected option in the popup. This value is assigned into the_Option.checkedattribute.wtforms-components redefines the "iter_choices()" method, so that the third item of the 3-tuple it yields is not the simple boolean, but a 2-tuple with a coerce function and a data value, which is what
__iter__()will now see. Internally wtforms handles this change since its widget knows about the revised output ofiter_choices().But the original WTForms__iter__()method doesn't, and assigns a bogus value to the "checked" attribute of the_Optioninstances it spits out.Should wtforms-components have re-implemented
SelectField.__iter__()so that it provides valid_Optionfields if you iterate the SelectField? Perhaps there is no legitmate use for iterating through the options of a SelectField like this, but I was using it to add HTML "data-" attributes on the individual "option" items, and got bit by this - all options come out with the HTML "selected" attribute set.