499 lines
19 KiB
Python
499 lines
19 KiB
Python
"""
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Form classes
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"""
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import copy
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from django.core.exceptions import NON_FIELD_ERRORS, ValidationError
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from django.forms.fields import Field, FileField
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from django.forms.utils import ErrorDict, ErrorList
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from django.forms.widgets import Media, MediaDefiningClass
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from django.utils.datastructures import MultiValueDict
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from django.utils.functional import cached_property
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from django.utils.html import conditional_escape, html_safe
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from django.utils.safestring import mark_safe
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from django.utils.translation import gettext as _
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from .renderers import get_default_renderer
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__all__ = ('BaseForm', 'Form')
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class DeclarativeFieldsMetaclass(MediaDefiningClass):
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"""Collect Fields declared on the base classes."""
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def __new__(mcs, name, bases, attrs):
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# Collect fields from current class.
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current_fields = []
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for key, value in list(attrs.items()):
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if isinstance(value, Field):
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current_fields.append((key, value))
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attrs.pop(key)
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attrs['declared_fields'] = dict(current_fields)
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new_class = super(DeclarativeFieldsMetaclass, mcs).__new__(mcs, name, bases, attrs)
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# Walk through the MRO.
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declared_fields = {}
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for base in reversed(new_class.__mro__):
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# Collect fields from base class.
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if hasattr(base, 'declared_fields'):
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declared_fields.update(base.declared_fields)
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# Field shadowing.
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for attr, value in base.__dict__.items():
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if value is None and attr in declared_fields:
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declared_fields.pop(attr)
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new_class.base_fields = declared_fields
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new_class.declared_fields = declared_fields
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return new_class
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@html_safe
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class BaseForm:
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"""
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The main implementation of all the Form logic. Note that this class is
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different than Form. See the comments by the Form class for more info. Any
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improvements to the form API should be made to this class, not to the Form
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class.
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"""
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default_renderer = None
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field_order = None
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prefix = None
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use_required_attribute = True
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def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
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initial=None, error_class=ErrorList, label_suffix=None,
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empty_permitted=False, field_order=None, use_required_attribute=None, renderer=None):
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self.is_bound = data is not None or files is not None
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self.data = MultiValueDict() if data is None else data
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self.files = MultiValueDict() if files is None else files
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self.auto_id = auto_id
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if prefix is not None:
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self.prefix = prefix
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self.initial = initial or {}
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self.error_class = error_class
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# Translators: This is the default suffix added to form field labels
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self.label_suffix = label_suffix if label_suffix is not None else _(':')
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self.empty_permitted = empty_permitted
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self._errors = None # Stores the errors after clean() has been called.
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# The base_fields class attribute is the *class-wide* definition of
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# fields. Because a particular *instance* of the class might want to
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# alter self.fields, we create self.fields here by copying base_fields.
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# Instances should always modify self.fields; they should not modify
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# self.base_fields.
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self.fields = copy.deepcopy(self.base_fields)
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self._bound_fields_cache = {}
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self.order_fields(self.field_order if field_order is None else field_order)
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if use_required_attribute is not None:
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self.use_required_attribute = use_required_attribute
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if self.empty_permitted and self.use_required_attribute:
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raise ValueError(
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'The empty_permitted and use_required_attribute arguments may '
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'not both be True.'
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)
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# Initialize form renderer. Use a global default if not specified
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# either as an argument or as self.default_renderer.
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if renderer is None:
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if self.default_renderer is None:
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renderer = get_default_renderer()
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else:
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renderer = self.default_renderer
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if isinstance(self.default_renderer, type):
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renderer = renderer()
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self.renderer = renderer
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def order_fields(self, field_order):
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"""
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Rearrange the fields according to field_order.
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field_order is a list of field names specifying the order. Append fields
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not included in the list in the default order for backward compatibility
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with subclasses not overriding field_order. If field_order is None,
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keep all fields in the order defined in the class. Ignore unknown
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fields in field_order to allow disabling fields in form subclasses
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without redefining ordering.
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"""
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if field_order is None:
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return
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fields = {}
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for key in field_order:
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try:
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fields[key] = self.fields.pop(key)
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except KeyError: # ignore unknown fields
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pass
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fields.update(self.fields) # add remaining fields in original order
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self.fields = fields
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def __str__(self):
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return self.as_table()
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def __repr__(self):
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if self._errors is None:
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is_valid = "Unknown"
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else:
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is_valid = self.is_bound and not self._errors
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return '<%(cls)s bound=%(bound)s, valid=%(valid)s, fields=(%(fields)s)>' % {
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'cls': self.__class__.__name__,
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'bound': self.is_bound,
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'valid': is_valid,
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'fields': ';'.join(self.fields),
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}
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def __iter__(self):
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for name in self.fields:
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yield self[name]
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def __getitem__(self, name):
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"""Return 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(
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"Key '%s' not found in '%s'. Choices are: %s." % (
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name,
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self.__class__.__name__,
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', '.join(sorted(self.fields)),
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)
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)
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if name not in self._bound_fields_cache:
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self._bound_fields_cache[name] = field.get_bound_field(self, name)
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return self._bound_fields_cache[name]
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@property
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def errors(self):
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"""Return an ErrorDict for the data provided for the form."""
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if self._errors is None:
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self.full_clean()
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return self._errors
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def is_valid(self):
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"""Return True if the form has no errors, or False otherwise."""
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return self.is_bound and not self.errors
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def add_prefix(self, field_name):
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"""
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Return the field name with a prefix appended, if this Form has a
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prefix set.
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Subclasses may wish to override.
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"""
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return '%s-%s' % (self.prefix, field_name) if self.prefix else field_name
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def add_initial_prefix(self, field_name):
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"""Add an 'initial' prefix for checking dynamic initial values."""
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return 'initial-%s' % self.add_prefix(field_name)
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def _html_output(self, normal_row, error_row, row_ender, help_text_html, errors_on_separate_row):
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"Output HTML. Used by as_table(), as_ul(), as_p()."
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top_errors = self.non_field_errors() # Errors that should be displayed above all fields.
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output, hidden_fields = [], []
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for name, field in self.fields.items():
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html_class_attr = ''
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bf = self[name]
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bf_errors = self.error_class(bf.errors)
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if bf.is_hidden:
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if bf_errors:
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top_errors.extend(
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[_('(Hidden field %(name)s) %(error)s') % {'name': name, 'error': str(e)}
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for e in bf_errors])
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hidden_fields.append(str(bf))
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else:
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# Create a 'class="..."' attribute if the row should have any
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# CSS classes applied.
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css_classes = bf.css_classes()
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if css_classes:
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html_class_attr = ' class="%s"' % css_classes
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if errors_on_separate_row and bf_errors:
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output.append(error_row % str(bf_errors))
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if bf.label:
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label = conditional_escape(bf.label)
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label = bf.label_tag(label) or ''
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else:
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label = ''
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if field.help_text:
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help_text = help_text_html % field.help_text
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else:
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help_text = ''
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output.append(normal_row % {
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'errors': bf_errors,
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'label': label,
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'field': bf,
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'help_text': help_text,
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'html_class_attr': html_class_attr,
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'css_classes': css_classes,
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'field_name': bf.html_name,
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})
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if top_errors:
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output.insert(0, error_row % top_errors)
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if hidden_fields: # Insert any hidden fields in the last row.
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str_hidden = ''.join(hidden_fields)
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if output:
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last_row = output[-1]
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# Chop off the trailing row_ender (e.g. '</td></tr>') and
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# insert the hidden fields.
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if not last_row.endswith(row_ender):
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# This can happen in the as_p() case (and possibly others
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# that users write): if there are only top errors, we may
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# not be able to conscript the last row for our purposes,
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# so insert a new, empty row.
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last_row = (normal_row % {
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'errors': '',
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'label': '',
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'field': '',
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'help_text': '',
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'html_class_attr': html_class_attr,
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'css_classes': '',
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'field_name': '',
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})
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output.append(last_row)
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output[-1] = last_row[:-len(row_ender)] + str_hidden + row_ender
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else:
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# If there aren't any rows in the output, just append the
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# hidden fields.
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output.append(str_hidden)
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return mark_safe('\n'.join(output))
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def as_table(self):
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"Return this form rendered as HTML <tr>s -- excluding the <table></table>."
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return self._html_output(
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normal_row='<tr%(html_class_attr)s><th>%(label)s</th><td>%(errors)s%(field)s%(help_text)s</td></tr>',
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error_row='<tr><td colspan="2">%s</td></tr>',
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row_ender='</td></tr>',
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help_text_html='<br><span class="helptext">%s</span>',
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errors_on_separate_row=False,
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)
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def as_ul(self):
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"Return this form rendered as HTML <li>s -- excluding the <ul></ul>."
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return self._html_output(
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normal_row='<li%(html_class_attr)s>%(errors)s%(label)s %(field)s%(help_text)s</li>',
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error_row='<li>%s</li>',
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row_ender='</li>',
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help_text_html=' <span class="helptext">%s</span>',
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errors_on_separate_row=False,
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)
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def as_p(self):
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"Return this form rendered as HTML <p>s."
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return self._html_output(
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normal_row='<p%(html_class_attr)s>%(label)s %(field)s%(help_text)s</p>',
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error_row='%s',
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row_ender='</p>',
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help_text_html=' <span class="helptext">%s</span>',
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errors_on_separate_row=True,
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)
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def non_field_errors(self):
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"""
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Return an ErrorList of errors that aren't associated with a particular
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field -- i.e., from Form.clean(). Return an empty ErrorList if there
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are none.
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"""
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return self.errors.get(NON_FIELD_ERRORS, self.error_class(error_class='nonfield'))
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def add_error(self, field, error):
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"""
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Update the content of `self._errors`.
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The `field` argument is the name of the field to which the errors
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should be added. If it's None, treat the errors as NON_FIELD_ERRORS.
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The `error` argument can be a single error, a list of errors, or a
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dictionary that maps field names to lists of errors. An "error" can be
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either a simple string or an instance of ValidationError with its
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message attribute set and a "list or dictionary" can be an actual
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`list` or `dict` or an instance of ValidationError with its
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`error_list` or `error_dict` attribute set.
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If `error` is a dictionary, the `field` argument *must* be None and
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errors will be added to the fields that correspond to the keys of the
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dictionary.
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"""
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if not isinstance(error, ValidationError):
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# Normalize to ValidationError and let its constructor
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# do the hard work of making sense of the input.
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error = ValidationError(error)
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if hasattr(error, 'error_dict'):
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if field is not None:
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raise TypeError(
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"The argument `field` must be `None` when the `error` "
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"argument contains errors for multiple fields."
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)
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else:
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error = error.error_dict
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else:
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error = {field or NON_FIELD_ERRORS: error.error_list}
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for field, error_list in error.items():
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if field not in self.errors:
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if field != NON_FIELD_ERRORS and field not in self.fields:
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raise ValueError(
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"'%s' has no field named '%s'." % (self.__class__.__name__, field))
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if field == NON_FIELD_ERRORS:
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self._errors[field] = self.error_class(error_class='nonfield')
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else:
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self._errors[field] = self.error_class()
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self._errors[field].extend(error_list)
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if field in self.cleaned_data:
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del self.cleaned_data[field]
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def has_error(self, field, code=None):
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return field in self.errors and (
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code is None or
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any(error.code == code for error in self.errors.as_data()[field])
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)
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def full_clean(self):
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"""
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Clean all of self.data and populate self._errors and self.cleaned_data.
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"""
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self._errors = ErrorDict()
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if not self.is_bound: # Stop further processing.
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return
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self.cleaned_data = {}
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# If the form is permitted to be empty, and none of the form data has
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# changed from the initial data, short circuit any validation.
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if self.empty_permitted and not self.has_changed():
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return
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self._clean_fields()
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self._clean_form()
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self._post_clean()
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def _clean_fields(self):
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for name, field in self.fields.items():
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# value_from_datadict() gets the data from the data dictionaries.
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# Each widget type knows how to retrieve its own data, because some
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# widgets split data over several HTML fields.
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if field.disabled:
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value = self.get_initial_for_field(field, name)
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else:
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value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
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try:
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if isinstance(field, FileField):
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initial = self.get_initial_for_field(field, name)
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value = field.clean(value, initial)
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else:
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value = field.clean(value)
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self.cleaned_data[name] = value
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if hasattr(self, 'clean_%s' % name):
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value = getattr(self, 'clean_%s' % name)()
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self.cleaned_data[name] = value
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except ValidationError as e:
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self.add_error(name, e)
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def _clean_form(self):
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try:
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cleaned_data = self.clean()
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except ValidationError as e:
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self.add_error(None, e)
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else:
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if cleaned_data is not None:
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self.cleaned_data = cleaned_data
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def _post_clean(self):
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"""
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An internal hook for performing additional cleaning after form cleaning
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is complete. Used for model validation in model forms.
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"""
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pass
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def clean(self):
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"""
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Hook for doing any extra form-wide cleaning after Field.clean() has been
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called on every field. Any ValidationError raised by this method will
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not be associated with a particular field; it will have a special-case
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association with the field named '__all__'.
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"""
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return self.cleaned_data
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def has_changed(self):
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"""Return True if data differs from initial."""
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return bool(self.changed_data)
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@cached_property
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def changed_data(self):
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data = []
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for name, field in self.fields.items():
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prefixed_name = self.add_prefix(name)
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data_value = field.widget.value_from_datadict(self.data, self.files, prefixed_name)
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if not field.show_hidden_initial:
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# Use the BoundField's initial as this is the value passed to
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# the widget.
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initial_value = self[name].initial
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else:
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initial_prefixed_name = self.add_initial_prefix(name)
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hidden_widget = field.hidden_widget()
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try:
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initial_value = field.to_python(hidden_widget.value_from_datadict(
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self.data, self.files, initial_prefixed_name))
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except ValidationError:
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# Always assume data has changed if validation fails.
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data.append(name)
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continue
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if field.has_changed(initial_value, data_value):
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data.append(name)
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return data
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@property
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def media(self):
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"""Return all media required to render the widgets on this form."""
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media = Media()
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for field in self.fields.values():
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media = media + field.widget.media
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return media
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def is_multipart(self):
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"""
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Return True if the form needs to be multipart-encoded, i.e. it has
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FileInput, or False otherwise.
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"""
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return any(field.widget.needs_multipart_form for field in self.fields.values())
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def hidden_fields(self):
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"""
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Return a list of all the BoundField objects that are hidden fields.
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Useful for manual form layout in templates.
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"""
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return [field for field in self if field.is_hidden]
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def visible_fields(self):
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"""
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Return a list of BoundField objects that aren't hidden fields.
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The opposite of the hidden_fields() method.
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"""
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return [field for field in self if not field.is_hidden]
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def get_initial_for_field(self, field, field_name):
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"""
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Return initial data for field on form. Use initial data from the form
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or the field, in that order. Evaluate callable values.
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"""
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value = self.initial.get(field_name, field.initial)
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if callable(value):
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value = value()
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return value
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class Form(BaseForm, metaclass=DeclarativeFieldsMetaclass):
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"A collection of Fields, plus their associated data."
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# This is a separate class from BaseForm in order to abstract the way
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# self.fields is specified. This class (Form) is the one that does the
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# fancy metaclass stuff purely for the semantic sugar -- it allows one
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# to define a form using declarative syntax.
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# BaseForm itself has no way of designating self.fields.
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