104 lines
3.4 KiB
Python
104 lines
3.4 KiB
Python
"""
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Form classes
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"""
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from fields import Field
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from widgets import TextInput, Textarea
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from util import ErrorDict, ErrorList, ValidationError
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class DeclarativeFieldsMetaclass(type):
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"Metaclass that converts Field attributes to a dictionary called 'fields'."
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def __new__(cls, name, bases, attrs):
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attrs['fields'] = dict([(name, attrs.pop(name)) for name, obj in attrs.items() if isinstance(obj, Field)])
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return type.__new__(cls, name, bases, attrs)
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class Form(object):
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"A collection of Fields, plus their associated data."
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__metaclass__ = DeclarativeFieldsMetaclass
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def __init__(self, data=None): # TODO: prefix stuff
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self.data = data or {}
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self.__data_python = None # Stores the data after to_python() has been called.
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self.__errors = None # Stores the errors after to_python() has been called.
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def __iter__(self):
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for name, field in self.fields.items():
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yield BoundField(self, field, name)
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def to_python(self):
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if self.__errors is None:
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self._validate()
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return self.__data_python
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def errors(self):
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"Returns an ErrorDict for self.data"
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if self.__errors is None:
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self._validate()
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return self.__errors
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def is_valid(self):
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"""
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Returns True if the form has no errors. Otherwise, False. This exists
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solely for convenience, so client code can use positive logic rather
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than confusing negative logic ("if not form.errors()").
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"""
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return not bool(self.errors())
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def __getitem__(self, name):
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"Returns a BoundField with the given name."
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try:
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field = self.fields[name]
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except KeyError:
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raise KeyError('Key %r not found in Form' % name)
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return BoundField(self, field, name)
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def _validate(self):
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data_python = {}
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errors = ErrorDict()
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for name, field in self.fields.items():
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try:
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value = field.to_python(self.data.get(name, None))
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data_python[name] = value
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except ValidationError, e:
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errors[name] = e.messages
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if not errors: # Only set self.data_python if there weren't errors.
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self.__data_python = data_python
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self.__errors = errors
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class BoundField(object):
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"A Field plus data"
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def __init__(self, form, field, name):
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self._form = form
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self._field = field
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self._name = name
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def __str__(self):
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"Renders this field as an HTML widget."
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# Use the 'widget' attribute on the field to determine which type
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# of HTML widget to use.
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return self.as_widget(self._field.widget)
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def _errors(self):
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"""
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Returns an ErrorList for this field. Returns an empty ErrorList
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if there are none.
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"""
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try:
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return self._form.errors()[self._name]
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except KeyError:
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return ErrorList()
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errors = property(_errors)
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def as_widget(self, widget, attrs=None):
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return widget.render(self._name, self._form.data.get(self._name, None), attrs=attrs)
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def as_text(self, attrs=None):
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"""
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Returns a string of HTML for representing this as an <input type="text">.
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"""
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return self.as_widget(TextInput(), attrs)
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def as_textarea(self, attrs=None):
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"Returns a string of HTML for representing this as a <textarea>."
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return self.as_widget(Textarea(), attrs)
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