app/django/forms/forms.py

   1 """
   2 Form classes
   3 """
   4
   5 from copy import deepcopy
   6
   7 from django.utils.datastructures import SortedDict
   8 from django.utils.html import escape
   9 from django.utils.encoding import StrAndUnicode, smart_unicode, force_unicode
  10 from django.utils.safestring import mark_safe
  11
  12 from fields import Field, FileField
  13 from widgets import Media, media_property, TextInput, Textarea
  14 from util import flatatt, ErrorDict, ErrorList, ValidationError
  15
  16 __all__ = ('BaseForm', 'Form')
  17
  18 NON_FIELD_ERRORS = '__all__'
  19
  20 def pretty_name(name):
  21     "Converts 'first_name' to 'First name'"
  22     name = name[0].upper() + name[1:]
  23     return name.replace('_', ' ')
  24
  25 def get_declared_fields(bases, attrs, with_base_fields=True):
  26     """
  27     Create a list of form field instances from the passed in 'attrs', plus any
  28     similar fields on the base classes (in 'bases'). This is used by both the
  29     Form and ModelForm metclasses.
  30
  31     If 'with_base_fields' is True, all fields from the bases are used.
  32     Otherwise, only fields in the 'declared_fields' attribute on the bases are
  33     used. The distinction is useful in ModelForm subclassing.
  34     Also integrates any additional media definitions
  35     """
  36     fields = [(field_name, attrs.pop(field_name)) for field_name, obj in attrs.items() if isinstance(obj, Field)]
  37     fields.sort(lambda x, y: cmp(x[1].creation_counter, y[1].creation_counter))
  38
  39     # If this class is subclassing another Form, add that Form's fields.
  40     # Note that we loop over the bases in *reverse*. This is necessary in
  41     # order to preserve the correct order of fields.
  42     if with_base_fields:
  43         for base in bases[::-1]:
  44             if hasattr(base, 'base_fields'):
  45                 fields = base.base_fields.items() + fields
  46     else:
  47         for base in bases[::-1]:
  48             if hasattr(base, 'declared_fields'):
  49                 fields = base.declared_fields.items() + fields
  50
  51     return SortedDict(fields)
  52
  53 class DeclarativeFieldsMetaclass(type):
  54     """
  55     Metaclass that converts Field attributes to a dictionary called
  56     'base_fields', taking into account parent class 'base_fields' as well.
  57     """
  58     def __new__(cls, name, bases, attrs):
  59         attrs['base_fields'] = get_declared_fields(bases, attrs)
  60         new_class = super(DeclarativeFieldsMetaclass,
  61                      cls).__new__(cls, name, bases, attrs)
  62         if 'media' not in attrs:
  63             new_class.media = media_property(new_class)
  64         return new_class
  65
  66 class BaseForm(StrAndUnicode):
  67     # This is the main implementation of all the Form logic. Note that this
  68     # class is different than Form. See the comments by the Form class for more
  69     # information. Any improvements to the form API should be made to *this*
  70     # class, not to the Form class.
  71     def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
  72                  initial=None, error_class=ErrorList, label_suffix=':',
  73                  empty_permitted=False):
  74         self.is_bound = data is not None or files is not None
  75         self.data = data or {}
  76         self.files = files or {}
  77         self.auto_id = auto_id
  78         self.prefix = prefix
  79         self.initial = initial or {}
  80         self.error_class = error_class
  81         self.label_suffix = label_suffix
  82         self.empty_permitted = empty_permitted
  83         self._errors = None # Stores the errors after clean() has been called.
  84         self._changed_data = None
  85
  86         # The base_fields class attribute is the *class-wide* definition of
  87         # fields. Because a particular *instance* of the class might want to
  88         # alter self.fields, we create self.fields here by copying base_fields.
  89         # Instances should always modify self.fields; they should not modify
  90         # self.base_fields.
  91         self.fields = deepcopy(self.base_fields)
  92
  93     def __unicode__(self):
  94         return self.as_table()
  95
  96     def __iter__(self):
  97         for name, field in self.fields.items():
  98             yield BoundField(self, field, name)
  99
 100     def __getitem__(self, name):
 101         "Returns a BoundField with the given name."
 102         try:
 103             field = self.fields[name]
 104         except KeyError:
 105             raise KeyError('Key %r not found in Form' % name)
 106         return BoundField(self, field, name)
 107
 108     def _get_errors(self):
 109         "Returns an ErrorDict for the data provided for the form"
 110         if self._errors is None:
 111             self.full_clean()
 112         return self._errors
 113     errors = property(_get_errors)
 114
 115     def is_valid(self):
 116         """
 117         Returns True if the form has no errors. Otherwise, False. If errors are
 118         being ignored, returns False.
 119         """
 120         return self.is_bound and not bool(self.errors)
 121
 122     def add_prefix(self, field_name):
 123         """
 124         Returns the field name with a prefix appended, if this Form has a
 125         prefix set.
 126
 127         Subclasses may wish to override.
 128         """
 129         return self.prefix and ('%s-%s' % (self.prefix, field_name)) or field_name
 130
 131     def add_initial_prefix(self, field_name):
 132         """
 133         Add a 'initial' prefix for checking dynamic initial values
 134         """
 135         return u'initial-%s' % self.add_prefix(field_name)
 136
 137     def _html_output(self, normal_row, error_row, row_ender, help_text_html, errors_on_separate_row):
 138         "Helper function for outputting HTML. Used by as_table(), as_ul(), as_p()."
 139         top_errors = self.non_field_errors() # Errors that should be displayed above all fields.
 140         output, hidden_fields = [], []
 141         for name, field in self.fields.items():
 142             bf = BoundField(self, field, name)
 143             bf_errors = self.error_class([escape(error) for error in bf.errors]) # Escape and cache in local variable.
 144             if bf.is_hidden:
 145                 if bf_errors:
 146                     top_errors.extend([u'(Hidden field %s) %s' % (name, force_unicode(e)) for e in bf_errors])
 147                 hidden_fields.append(unicode(bf))
 148             else:
 149                 if errors_on_separate_row and bf_errors:
 150                     output.append(error_row % force_unicode(bf_errors))
 151                 if bf.label:
 152                     label = escape(force_unicode(bf.label))
 153                     # Only add the suffix if the label does not end in
 154                     # punctuation.
 155                     if self.label_suffix:
 156                         if label[-1] not in ':?.!':
 157                             label += self.label_suffix
 158                     label = bf.label_tag(label) or ''
 159                 else:
 160                     label = ''
 161                 if field.help_text:
 162                     help_text = help_text_html % force_unicode(field.help_text)
 163                 else:
 164                     help_text = u''
 165                 output.append(normal_row % {'errors': force_unicode(bf_errors), 'label': force_unicode(label), 'field': unicode(bf), 'help_text': help_text})
 166         if top_errors:
 167             output.insert(0, error_row % force_unicode(top_errors))
 168         if hidden_fields: # Insert any hidden fields in the last row.
 169             str_hidden = u''.join(hidden_fields)
 170             if output:
 171                 last_row = output[-1]
 172                 # Chop off the trailing row_ender (e.g. '</td></tr>') and
 173                 # insert the hidden fields.
 174                 if not last_row.endswith(row_ender):
 175                     # This can happen in the as_p() case (and possibly others
 176                     # that users write): if there are only top errors, we may
 177                     # not be able to conscript the last row for our purposes,
 178                     # so insert a new, empty row.
 179                     last_row = normal_row % {'errors': '', 'label': '', 'field': '', 'help_text': ''}
 180                     output.append(last_row)
 181                 output[-1] = last_row[:-len(row_ender)] + str_hidden + row_ender
 182             else:
 183                 # If there aren't any rows in the output, just append the
 184                 # hidden fields.
 185                 output.append(str_hidden)
 186         return mark_safe(u'\n'.join(output))
 187
 188     def as_table(self):
 189         "Returns this form rendered as HTML <tr>s -- excluding the <table></table>."
 190         return self._html_output(u'<tr><th>%(label)s</th><td>%(errors)s%(field)s%(help_text)s</td></tr>', u'<tr><td colspan="2">%s</td></tr>', '</td></tr>', u'<br />%s', False)
 191
 192     def as_ul(self):
 193         "Returns this form rendered as HTML <li>s -- excluding the <ul></ul>."
 194         return self._html_output(u'<li>%(errors)s%(label)s %(field)s%(help_text)s</li>', u'<li>%s</li>', '</li>', u' %s', False)
 195
 196     def as_p(self):
 197         "Returns this form rendered as HTML <p>s."
 198         return self._html_output(u'<p>%(label)s %(field)s%(help_text)s</p>', u'%s', '</p>', u' %s', True)
 199
 200     def non_field_errors(self):
 201         """
 202         Returns an ErrorList of errors that aren't associated with a particular
 203         field -- i.e., from Form.clean(). Returns an empty ErrorList if there
 204         are none.
 205         """
 206         return self.errors.get(NON_FIELD_ERRORS, self.error_class())
 207
 208     def full_clean(self):
 209         """
 210         Cleans all of self.data and populates self._errors and
 211         self.cleaned_data.
 212         """
 213         self._errors = ErrorDict()
 214         if not self.is_bound: # Stop further processing.
 215             return
 216         self.cleaned_data = {}
 217         # If the form is permitted to be empty, and none of the form data has
 218         # changed from the initial data, short circuit any validation.
 219         if self.empty_permitted and not self.has_changed():
 220             return
 221         for name, field in self.fields.items():
 222             # value_from_datadict() gets the data from the data dictionaries.
 223             # Each widget type knows how to retrieve its own data, because some
 224             # widgets split data over several HTML fields.
 225             value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
 226             try:
 227                 if isinstance(field, FileField):
 228                     initial = self.initial.get(name, field.initial)
 229                     value = field.clean(value, initial)
 230                 else:
 231                     value = field.clean(value)
 232                 self.cleaned_data[name] = value
 233                 if hasattr(self, 'clean_%s' % name):
 234                     value = getattr(self, 'clean_%s' % name)()
 235                     self.cleaned_data[name] = value
 236             except ValidationError, e:
 237                 self._errors[name] = e.messages
 238                 if name in self.cleaned_data:
 239                     del self.cleaned_data[name]
 240         try:
 241             self.cleaned_data = self.clean()
 242         except ValidationError, e:
 243             self._errors[NON_FIELD_ERRORS] = e.messages
 244         if self._errors:
 245             delattr(self, 'cleaned_data')
 246
 247     def clean(self):
 248         """
 249         Hook for doing any extra form-wide cleaning after Field.clean() been
 250         called on every field. Any ValidationError raised by this method will
 251         not be associated with a particular field; it will have a special-case
 252         association with the field named '__all__'.
 253         """
 254         return self.cleaned_data
 255
 256     def has_changed(self):
 257         """
 258         Returns True if data differs from initial.
 259         """
 260         return bool(self.changed_data)
 261
 262     def _get_changed_data(self):
 263         if self._changed_data is None:
 264             self._changed_data = []
 265             # XXX: For now we're asking the individual widgets whether or not the
 266             # data has changed. It would probably be more efficient to hash the
 267             # initial data, store it in a hidden field, and compare a hash of the
 268             # submitted data, but we'd need a way to easily get the string value
 269             # for a given field. Right now, that logic is embedded in the render
 270             # method of each widget.
 271             for name, field in self.fields.items():
 272                 prefixed_name = self.add_prefix(name)
 273                 data_value = field.widget.value_from_datadict(self.data, self.files, prefixed_name)
 274                 if not field.show_hidden_initial:
 275                     initial_value = self.initial.get(name, field.initial)
 276                 else:
 277                     initial_prefixed_name = self.add_initial_prefix(name)
 278                     hidden_widget = field.hidden_widget()
 279                     initial_value = hidden_widget.value_from_datadict(
 280                         self.data, self.files, initial_prefixed_name)
 281                 if field.widget._has_changed(initial_value, data_value):
 282                     self._changed_data.append(name)
 283         return self._changed_data
 284     changed_data = property(_get_changed_data)
 285
 286     def _get_media(self):
 287         """
 288         Provide a description of all media required to render the widgets on this form
 289         """
 290         media = Media()
 291         for field in self.fields.values():
 292             media = media + field.widget.media
 293         return media
 294     media = property(_get_media)
 295
 296     def is_multipart(self):
 297         """
 298         Returns True if the form needs to be multipart-encrypted, i.e. it has
 299         FileInput. Otherwise, False.
 300         """
 301         for field in self.fields.values():
 302             if field.widget.needs_multipart_form:
 303                 return True
 304         return False
 305
 306 class Form(BaseForm):
 307     "A collection of Fields, plus their associated data."
 308     # This is a separate class from BaseForm in order to abstract the way
 309     # self.fields is specified. This class (Form) is the one that does the
 310     # fancy metaclass stuff purely for the semantic sugar -- it allows one
 311     # to define a form using declarative syntax.
 312     # BaseForm itself has no way of designating self.fields.
 313     __metaclass__ = DeclarativeFieldsMetaclass
 314
 315 class BoundField(StrAndUnicode):
 316     "A Field plus data"
 317     def __init__(self, form, field, name):
 318         self.form = form
 319         self.field = field
 320         self.name = name
 321         self.html_name = form.add_prefix(name)
 322         self.html_initial_name = form.add_initial_prefix(name)
 323         if self.field.label is None:
 324             self.label = pretty_name(name)
 325         else:
 326             self.label = self.field.label
 327         self.help_text = field.help_text or ''
 328
 329     def __unicode__(self):
 330         """Renders this field as an HTML widget."""
 331         if self.field.show_hidden_initial:
 332             return self.as_widget() + self.as_hidden(only_initial=True)
 333         return self.as_widget()
 334
 335     def _errors(self):
 336         """
 337         Returns an ErrorList for this field. Returns an empty ErrorList
 338         if there are none.
 339         """
 340         return self.form.errors.get(self.name, self.form.error_class())
 341     errors = property(_errors)
 342
 343     def as_widget(self, widget=None, attrs=None, only_initial=False):
 344         """
 345         Renders the field by rendering the passed widget, adding any HTML
 346         attributes passed as attrs.  If no widget is specified, then the
 347         field's default widget will be used.
 348         """
 349         if not widget:
 350             widget = self.field.widget
 351         attrs = attrs or {}
 352         auto_id = self.auto_id
 353         if auto_id and 'id' not in attrs and 'id' not in widget.attrs:
 354             attrs['id'] = auto_id
 355         if not self.form.is_bound:
 356             data = self.form.initial.get(self.name, self.field.initial)
 357             if callable(data):
 358                 data = data()
 359         else:
 360             data = self.data
 361         if not only_initial:
 362             name = self.html_name
 363         else:
 364             name = self.html_initial_name
 365         return widget.render(name, data, attrs=attrs)
 366
 367     def as_text(self, attrs=None, **kwargs):
 368         """
 369         Returns a string of HTML for representing this as an <input type="text">.
 370         """
 371         return self.as_widget(TextInput(), attrs, **kwargs)
 372
 373     def as_textarea(self, attrs=None, **kwargs):
 374         "Returns a string of HTML for representing this as a <textarea>."
 375         return self.as_widget(Textarea(), attrs, **kwargs)
 376
 377     def as_hidden(self, attrs=None, **kwargs):
 378         """
 379         Returns a string of HTML for representing this as an <input type="hidden">.
 380         """
 381         return self.as_widget(self.field.hidden_widget(), attrs, **kwargs)
 382
 383     def _data(self):
 384         """
 385         Returns the data for this BoundField, or None if it wasn't given.
 386         """
 387         return self.field.widget.value_from_datadict(self.form.data, self.form.files, self.html_name)
 388     data = property(_data)
 389
 390     def label_tag(self, contents=None, attrs=None):
 391         """
 392         Wraps the given contents in a <label>, if the field has an ID attribute.
 393         Does not HTML-escape the contents. If contents aren't given, uses the
 394         field's HTML-escaped label.
 395
 396         If attrs are given, they're used as HTML attributes on the <label> tag.
 397         """
 398         contents = contents or escape(self.label)
 399         widget = self.field.widget
 400         id_ = widget.attrs.get('id') or self.auto_id
 401         if id_:
 402             attrs = attrs and flatatt(attrs) or ''
 403             contents = u'<label for="%s"%s>%s</label>' % (widget.id_for_label(id_), attrs, unicode(contents))
 404         return mark_safe(contents)
 405
 406     def _is_hidden(self):
 407         "Returns True if this BoundField's widget is hidden."
 408         return self.field.widget.is_hidden
 409     is_hidden = property(_is_hidden)
 410
 411     def _auto_id(self):
 412         """
 413         Calculates and returns the ID attribute for this BoundField, if the
 414         associated Form has specified auto_id. Returns an empty string otherwise.
 415         """
 416         auto_id = self.form.auto_id
 417         if auto_id and '%s' in smart_unicode(auto_id):
 418             return smart_unicode(auto_id) % self.html_name
 419         elif auto_id:
 420             return self.html_name
 421         return ''
 422     auto_id = property(_auto_id)