在 flask-wtforms 中自动设置表单元素的 id HTML 属性

Question

Is there a way to automatically have the id of a form input element itself to the name of the form and the name of the field variable? ie for a bar field in a FooForm instance, the id would be foo-form--bar .

I am currently using this approach to achieve this, but it's a bit cumbersome:

from flask_wtf import FlaskForm
import wtforms as wtf

class FooForm(FlaskForm):
    FORM_NAME = 'foo-form'
    bar =  wtf.StringField('Bar', render_kw={'id': f'{FORM_NAME}--bar'})

Answer 1

I think subclassing complicates this, since the subclass contains only one or two lines. You can do the following:

def class_id(s):
    """Convert input string from PascalCase to kebab-case"""
    import re
    return re.sub(r'(?<!^)(?=[A-Z])', '-', s).lower() + '-'

class MyClass(object):
    form_name = class_id(__qualname__)
    print(f"{form_name}attribute")

class OtherClass(object):
    form_name = class_id(__qualname__)
    print(f"{form_name}attribute")

>>> MyClass()
>>> OtherClass()
my-class-attribute
other-class-attribute

edit: sorry completely missed the part about the id being automatic, then subclassing would be necessary, a simple approach would be:

def AdjStringField(form_name, **kwargs):
    name = kwargs.get('name', 'Bar')
    return wtf.StringField(name, render_kw={
        'id': f'{}{}'.format(form_name, name.lower(),
        **kwargs.get('render_kw', {})})

class FooForm(FlaskForm):
    form_name = class_id(__qualname__)
    bar = AdjStringField(form_name)
    pipe = AdjStringField(form_name, name='Pipe', render_kw={'foo': 'bar'})

You can overload this for any input field type provided you supplied it as in argument object:

def AdjField(Field, form_name, **kwargs):
    name = kwargs.get('name', 'Bar')
    return Field(name, render_kw={
        'id': f'{}{}'.format(form_name, name.lower(),
        **kwargs.get('render_kw', {})})

>>> AdjField(wtf.StringField, 'form-name')
>>> AdjField(wtf.InputBox, 'other-name', name='Pipe', render_kw={'foo': 'bar'})