# Django 1.8.18.dev20170123152445 documentation

# Source code for django.forms.forms

    """
    Form classes
    """

    from __future__ import unicode_literals

    import copy
    import datetime
    import warnings
    from collections import OrderedDict

    from django.core.exceptions import NON_FIELD_ERRORS, ValidationError
    from django.forms.fields import Field, FileField
    from django.forms.utils import ErrorDict, ErrorList, flatatt
    from django.forms.widgets import Media, MediaDefiningClass, Textarea, TextInput
    from django.utils import six
    from django.utils.deprecation import RemovedInDjango19Warning
    from django.utils.encoding import (
        force_text, python_2_unicode_compatible, smart_text,
    )
    from django.utils.html import conditional_escape, format_html, html_safe
    from django.utils.safestring import mark_safe
    from django.utils.translation import ugettext as _

    __all__ = ('BaseForm', 'Form')

    def pretty_name(name):
        """Converts 'first_name' to 'First name'"""
        if not name:
            return ''
        return name.replace('_', ' ').capitalize()

    UNSET = object()

    def get_declared_fields(bases, attrs, with_base_fields=True):
        """
        Create a list of form field instances from the passed in 'attrs', plus any
        similar fields on the base classes (in 'bases'). This is used by both the
        Form and ModelForm metaclasses.

        If 'with_base_fields' is True, all fields from the bases are used.
        Otherwise, only fields in the 'declared_fields' attribute on the bases are
        used. The distinction is useful in ModelForm subclassing.
        Also integrates any additional media definitions.
        """

        warnings.warn(
            "get_declared_fields is deprecated and will be removed in Django 1.9.",
            RemovedInDjango19Warning,
            stacklevel=2,
        )

        fields = [
            (field_name, attrs.pop(field_name))
            for field_name, obj in list(six.iteritems(attrs)) if isinstance(obj, Field)
        ]
        fields.sort(key=lambda x: x[1].creation_counter)

        # If this class is subclassing another Form, add that Form's fields.
        # Note that we loop over the bases in *reverse*. This is necessary in
        # order to preserve the correct order of fields.
        if with_base_fields:
            for base in bases[::-1]:
                if hasattr(base, 'base_fields'):
                    fields = list(six.iteritems(base.base_fields)) + fields
        else:
            for base in bases[::-1]:
                if hasattr(base, 'declared_fields'):
                    fields = list(six.iteritems(base.declared_fields)) + fields

        return OrderedDict(fields)

    class DeclarativeFieldsMetaclass(MediaDefiningClass):
        """
        Metaclass that collects Fields declared on the base classes.
        """
        def __new__(mcs, name, bases, attrs):
            # Collect fields from current class.
            current_fields = []
            for key, value in list(attrs.items()):
                if isinstance(value, Field):
                    current_fields.append((key, value))
                    attrs.pop(key)
            current_fields.sort(key=lambda x: x[1].creation_counter)
            attrs['declared_fields'] = OrderedDict(current_fields)

            new_class = (super(DeclarativeFieldsMetaclass, mcs)
                .__new__(mcs, name, bases, attrs))

            # Walk through the MRO.
            declared_fields = OrderedDict()
            for base in reversed(new_class.__mro__):
                # Collect fields from base class.
                if hasattr(base, 'declared_fields'):
                    declared_fields.update(base.declared_fields)

                # Field shadowing.
                for attr, value in base.__dict__.items():
                    if value is None and attr in declared_fields:
                        declared_fields.pop(attr)

            new_class.base_fields = declared_fields
            new_class.declared_fields = declared_fields

            return new_class

    @html_safe
    @python_2_unicode_compatible
    class BaseForm(object):
        # This is the main implementation of all the Form logic. Note that this
        # class is different than Form. See the comments by the Form class for more
        # information. Any improvements to the form API should be made to *this*
        # class, not to the Form class.
        def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
                     initial=None, error_class=ErrorList, label_suffix=None,
                     empty_permitted=False):
            self.is_bound = data is not None or files is not None
            self.data = data or {}
            self.files = files or {}
            self.auto_id = auto_id
            self.prefix = prefix
            self.initial = initial or {}
            self.error_class = error_class
            # Translators: This is the default suffix added to form field labels
            self.label_suffix = label_suffix if label_suffix is not None else _(':')
            self.empty_permitted = empty_permitted
            self._errors = None  # Stores the errors after clean() has been called.
            self._changed_data = None

            # The base_fields class attribute is the *class-wide* definition of
            # fields. Because a particular *instance* of the class might want to
            # alter self.fields, we create self.fields here by copying base_fields.
            # Instances should always modify self.fields; they should not modify
            # self.base_fields.
            self.fields = copy.deepcopy(self.base_fields)
            self._bound_fields_cache = {}

        def __str__(self):
            return self.as_table()

        def __repr__(self):
            if self._errors is None:
                is_valid = "Unknown"
            else:
                is_valid = self.is_bound and not bool(self._errors)
            return '<%(cls)s bound=%(bound)s, valid=%(valid)s, fields=(%(fields)s)>' % {
                'cls': self.__class__.__name__,
                'bound': self.is_bound,
                'valid': is_valid,
                'fields': ';'.join(self.fields),
            }

        def __iter__(self):
            for name in self.fields:
                yield self[name]

        def __getitem__(self, name):
            "Returns a BoundField with the given name."
            try:
                field = self.fields[name]
            except KeyError:
                raise KeyError(
                    "Key %r not found in '%s'" % (name, self.__class__.__name__))
            if name not in self._bound_fields_cache:
                self._bound_fields_cache[name] = BoundField(self, field, name)
            return self._bound_fields_cache[name]

        @property
        def errors(self):
            "Returns an ErrorDict for the data provided for the form"
            if self._errors is None:
                self.full_clean()
            return self._errors

        def is_valid(self):
            """
            Returns True if the form has no errors. Otherwise, False. If errors are
            being ignored, returns False.
            """
            return self.is_bound and not self.errors

        def add_prefix(self, field_name):
            """
            Returns the field name with a prefix appended, if this Form has a
            prefix set.

            Subclasses may wish to override.
            """
            return '%s-%s' % (self.prefix, field_name) if self.prefix else field_name

        def add_initial_prefix(self, field_name):
            """
            Add a 'initial' prefix for checking dynamic initial values
            """
            return 'initial-%s' % self.add_prefix(field_name)

        def _html_output(self, normal_row, error_row, row_ender, help_text_html, errors_on_separate_row):
            "Helper function for outputting HTML. Used by as_table(), as_ul(), as_p()."
            top_errors = self.non_field_errors()  # Errors that should be displayed above all fields.
            output, hidden_fields = [], []

            for name, field in self.fields.items():
                html_class_attr = ''
                bf = self[name]
                # Escape and cache in local variable.
                bf_errors = self.error_class([conditional_escape(error) for error in bf.errors])
                if bf.is_hidden:
                    if bf_errors:
                        top_errors.extend(
                            [_('(Hidden field %(name)s) %(error)s') % {'name': name, 'error': force_text(e)}
                             for e in bf_errors])
                    hidden_fields.append(six.text_type(bf))
                else:
                    # Create a 'class="..."' attribute if the row should have any
                    # CSS classes applied.
                    css_classes = bf.css_classes()
                    if css_classes:
                        html_class_attr = ' class="%s"' % css_classes

                    if errors_on_separate_row and bf_errors:
                        output.append(error_row % force_text(bf_errors))

                    if bf.label:
                        label = conditional_escape(force_text(bf.label))
                        label = bf.label_tag(label) or ''
                    else:
                        label = ''

                    if field.help_text:
                        help_text = help_text_html % force_text(field.help_text)
                    else:
                        help_text = ''

                    output.append(normal_row % {
                        'errors': force_text(bf_errors),
                        'label': force_text(label),
                        'field': six.text_type(bf),
                        'help_text': help_text,
                        'html_class_attr': html_class_attr,
                        'field_name': bf.html_name,
                    })

            if top_errors:
                output.insert(0, error_row % force_text(top_errors))

            if hidden_fields:  # Insert any hidden fields in the last row.
                str_hidden = ''.join(hidden_fields)
                if output:
                    last_row = output[-1]
                    # Chop off the trailing row_ender (e.g. '</td></tr>') and
                    # insert the hidden fields.
                    if not last_row.endswith(row_ender):
                        # This can happen in the as_p() case (and possibly others
                        # that users write): if there are only top errors, we may
                        # not be able to conscript the last row for our purposes,
                        # so insert a new, empty row.
                        last_row = (normal_row % {
                            'errors': '',
                            'label': '',
                            'field': '',
                            'help_text': '',
                            'html_class_attr': html_class_attr,
                            'field_name': '',
                        })
                        output.append(last_row)
                    output[-1] = last_row[:-len(row_ender)] + str_hidden + row_ender
                else:
                    # If there aren't any rows in the output, just append the
                    # hidden fields.
                    output.append(str_hidden)
            return mark_safe('\n'.join(output))

        def as_table(self):
            "Returns this form rendered as HTML <tr>s -- excluding the <table></table>."
            return self._html_output(
                normal_row='<tr%(html_class_attr)s><th>%(label)s</th><td>%(errors)s%(field)s%(help_text)s</td></tr>',
                error_row='<tr><td colspan="2">%s</td></tr>',
                row_ender='</td></tr>',
                help_text_html='<br /><span class="helptext">%s</span>',
                errors_on_separate_row=False)

        def as_ul(self):
            "Returns this form rendered as HTML <li>s -- excluding the <ul></ul>."
            return self._html_output(
                normal_row='<li%(html_class_attr)s>%(errors)s%(label)s %(field)s%(help_text)s</li>',
                error_row='<li>%s</li>',
                row_ender='</li>',
                help_text_html=' <span class="helptext">%s</span>',
                errors_on_separate_row=False)

        def as_p(self):
            "Returns this form rendered as HTML <p>s."
            return self._html_output(
                normal_row='<p%(html_class_attr)s>%(label)s %(field)s%(help_text)s</p>',
                error_row='%s',
                row_ender='</p>',
                help_text_html=' <span class="helptext">%s</span>',
                errors_on_separate_row=True)

        def non_field_errors(self):
            """
            Returns an ErrorList of errors that aren't associated with a particular
            field -- i.e., from Form.clean(). Returns an empty ErrorList if there
            are none.
            """
            return self.errors.get(NON_FIELD_ERRORS, self.error_class(error_class='nonfield'))

        def _raw_value(self, fieldname):
            """
            Returns the raw_value for a particular field name. This is just a
            convenient wrapper around widget.value_from_datadict.
            """
            field = self.fields[fieldname]
            prefix = self.add_prefix(fieldname)
            return field.widget.value_from_datadict(self.data, self.files, prefix)

        def add_error(self, field, error):
            """
            Update the content of `self._errors`.

            The `field` argument is the name of the field to which the errors
            should be added. If its value is None the errors will be treated as
            NON_FIELD_ERRORS.

            The `error` argument can be a single error, a list of errors, or a
            dictionary that maps field names to lists of errors. What we define as
            an "error" can be either a simple string or an instance of
            ValidationError with its message attribute set and what we define as
            list or dictionary can be an actual `list` or `dict` or an instance
            of ValidationError with its `error_list` or `error_dict` attribute set.

            If `error` is a dictionary, the `field` argument *must* be None and
            errors will be added to the fields that correspond to the keys of the
            dictionary.
            """
            if not isinstance(error, ValidationError):
                # Normalize to ValidationError and let its constructor
                # do the hard work of making sense of the input.
                error = ValidationError(error)

            if hasattr(error, 'error_dict'):
                if field is not None:
                    raise TypeError(
                        "The argument `field` must be `None` when the `error` "
                        "argument contains errors for multiple fields."
                    )
                else:
                    error = error.error_dict
            else:
                error = {field or NON_FIELD_ERRORS: error.error_list}

            for field, error_list in error.items():
                if field not in self.errors:
                    if field != NON_FIELD_ERRORS and field not in self.fields:
                        raise ValueError(
                            "'%s' has no field named '%s'." % (self.__class__.__name__, field))
                    if field == NON_FIELD_ERRORS:
                        self._errors[field] = self.error_class(error_class='nonfield')
                    else:
                        self._errors[field] = self.error_class()
                self._errors[field].extend(error_list)
                if field in self.cleaned_data:
                    del self.cleaned_data[field]

        def has_error(self, field, code=None):
            if code is None:
                return field in self.errors
            if field in self.errors:
                for error in self.errors.as_data()[field]:
                    if error.code == code:
                        return True
            return False

        def full_clean(self):
            """
            Cleans all of self.data and populates self._errors and
            self.cleaned_data.
            """
            self._errors = ErrorDict()
            if not self.is_bound:  # Stop further processing.
                return
            self.cleaned_data = {}
            # If the form is permitted to be empty, and none of the form data has
            # changed from the initial data, short circuit any validation.
            if self.empty_permitted and not self.has_changed():
                return

            self._clean_fields()
            self._clean_form()
            self._post_clean()

        def _clean_fields(self):
            for name, field in self.fields.items():
                # value_from_datadict() gets the data from the data dictionaries.
                # Each widget type knows how to retrieve its own data, because some
                # widgets split data over several HTML fields.
                value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
                try:
                    if isinstance(field, FileField):
                        initial = self.initial.get(name, field.initial)
                        value = field.clean(value, initial)
                    else:
                        value = field.clean(value)
                    self.cleaned_data[name] = value
                    if hasattr(self, 'clean_%s' % name):
                        value = getattr(self, 'clean_%s' % name)()
                        self.cleaned_data[name] = value
                except ValidationError as e:
                    self.add_error(name, e)

        def _clean_form(self):
            try:
                cleaned_data = self.clean()
            except ValidationError as e:
                self.add_error(None, e)
            else:
                if cleaned_data is not None:
                    self.cleaned_data = cleaned_data

        def _post_clean(self):
            """
            An internal hook for performing additional cleaning after form cleaning
            is complete. Used for model validation in model forms.
            """
            pass

        def clean(self):
            """
            Hook for doing any extra form-wide cleaning after Field.clean() has been
            called on every field. Any ValidationError raised by this method will
            not be associated with a particular field; it will have a special-case
            association with the field named '__all__'.
            """
            return self.cleaned_data

        def has_changed(self):
            """
            Returns True if data differs from initial.
            """
            return bool(self.changed_data)

        @property
        def changed_data(self):
            if self._changed_data is None:
                self._changed_data = []
                for name, field in self.fields.items():
                    prefixed_name = self.add_prefix(name)
                    data_value = field.widget.value_from_datadict(self.data, self.files, prefixed_name)
                    if not field.show_hidden_initial:
                        initial_value = self.initial.get(name, field.initial)
                        if callable(initial_value):
                            initial_value = initial_value()
                    else:
                        initial_prefixed_name = self.add_initial_prefix(name)
                        hidden_widget = field.hidden_widget()
                        try:
                            initial_value = field.to_python(hidden_widget.value_from_datadict(
                                self.data, self.files, initial_prefixed_name))
                        except ValidationError:
                            # Always assume data has changed if validation fails.
                            self._changed_data.append(name)
                            continue
                    if field.has_changed(initial_value, data_value):
                        self._changed_data.append(name)
            return self._changed_data

        @property
        def media(self):
            """
            Provide a description of all media required to render the widgets on this form
            """
            media = Media()
            for field in self.fields.values():
                media = media + field.widget.media
            return media

        def is_multipart(self):
            """
            Returns True if the form needs to be multipart-encoded, i.e. it has
            FileInput. Otherwise, False.
            """
            for field in self.fields.values():
                if field.widget.needs_multipart_form:
                    return True
            return False

        def hidden_fields(self):
            """
            Returns a list of all the BoundField objects that are hidden fields.
            Useful for manual form layout in templates.
            """
            return [field for field in self if field.is_hidden]

        def visible_fields(self):
            """
            Returns a list of BoundField objects that aren't hidden fields.
            The opposite of the hidden_fields() method.
            """
            return [field for field in self if not field.is_hidden]

    class Form(six.with_metaclass(DeclarativeFieldsMetaclass, BaseForm)):
        "A collection of Fields, plus their associated data."
        # This is a separate class from BaseForm in order to abstract the way
        # self.fields is specified. This class (Form) is the one that does the
        # fancy metaclass stuff purely for the semantic sugar -- it allows one
        # to define a form using declarative syntax.
        # BaseForm itself has no way of designating self.fields.

    @html_safe
    @python_2_unicode_compatible
    class BoundField(object):
        "A Field plus data"
        def __init__(self, form, field, name):
            self.form = form
            self.field = field
            self.name = name
            self.html_name = form.add_prefix(name)
            self.html_initial_name = form.add_initial_prefix(name)
            self.html_initial_id = form.add_initial_prefix(self.auto_id)
            if self.field.label is None:
                self.label = pretty_name(name)
            else:
                self.label = self.field.label
            self.help_text = field.help_text or ''
            self._initial_value = UNSET

        def __str__(self):
            """Renders this field as an HTML widget."""
            if self.field.show_hidden_initial:
                return self.as_widget() + self.as_hidden(only_initial=True)
            return self.as_widget()

        def __iter__(self):
            """
            Yields rendered strings that comprise all widgets in this BoundField.

            This really is only useful for RadioSelect widgets, so that you can
            iterate over individual radio buttons in a template.
            """
            id_ = self.field.widget.attrs.get('id') or self.auto_id
            attrs = {'id': id_} if id_ else {}
            for subwidget in self.field.widget.subwidgets(self.html_name, self.value(), attrs):
                yield subwidget

        def __len__(self):
            return len(list(self.__iter__()))

        def __getitem__(self, idx):
            # Prevent unnecessary reevaluation when accessing BoundField's attrs
            # from templates.
            if not isinstance(idx, six.integer_types + (slice,)):
                raise TypeError
            return list(self.__iter__())[idx]

        @property
        def errors(self):
            """
            Returns an ErrorList for this field. Returns an empty ErrorList
            if there are none.
            """
            return self.form.errors.get(self.name, self.form.error_class())

        def as_widget(self, widget=None, attrs=None, only_initial=False):
            """
            Renders the field by rendering the passed widget, adding any HTML
            attributes passed as attrs.  If no widget is specified, then the
            field's default widget will be used.
            """
            if not widget:
                widget = self.field.widget

            if self.field.localize:
                widget.is_localized = True

            attrs = attrs or {}
            auto_id = self.auto_id
            if auto_id and 'id' not in attrs and 'id' not in widget.attrs:
                if not only_initial:
                    attrs['id'] = auto_id
                else:
                    attrs['id'] = self.html_initial_id

            if not only_initial:
                name = self.html_name
            else:
                name = self.html_initial_name
            return force_text(widget.render(name, self.value(), attrs=attrs))

        def as_text(self, attrs=None, **kwargs):
            """
            Returns a string of HTML for representing this as an <input type="text">.
            """
            return self.as_widget(TextInput(), attrs, **kwargs)

        def as_textarea(self, attrs=None, **kwargs):
            "Returns a string of HTML for representing this as a <textarea>."
            return self.as_widget(Textarea(), attrs, **kwargs)

        def as_hidden(self, attrs=None, **kwargs):
            """
            Returns a string of HTML for representing this as an <input type="hidden">.
            """
            return self.as_widget(self.field.hidden_widget(), attrs, **kwargs)

        @property
        def data(self):
            """
            Returns the data for this BoundField, or None if it wasn't given.
            """
            return self.field.widget.value_from_datadict(self.form.data, self.form.files, self.html_name)

        def value(self):
            """
            Returns the value for this BoundField, using the initial value if
            the form is not bound or the data otherwise.
            """
            if not self.form.is_bound:
                data = self.form.initial.get(self.name, self.field.initial)
                if callable(data):
                    if self._initial_value is not UNSET:
                        data = self._initial_value
                    else:
                        data = data()
                        # If this is an auto-generated default date, nix the
                        # microseconds for standardized handling. See #22502.
                        if (isinstance(data, (datetime.datetime, datetime.time)) and
                                not getattr(self.field.widget, 'supports_microseconds', True)):
                            data = data.replace(microsecond=0)
                        self._initial_value = data
            else:
                data = self.field.bound_data(
                    self.data, self.form.initial.get(self.name, self.field.initial)
                )
            return self.field.prepare_value(data)

        def label_tag(self, contents=None, attrs=None, label_suffix=None):
            """
            Wraps the given contents in a <label>, if the field has an ID attribute.
            contents should be 'mark_safe'd to avoid HTML escaping. If contents
            aren't given, uses the field's HTML-escaped label.

            If attrs are given, they're used as HTML attributes on the <label> tag.

            label_suffix allows overriding the form's label_suffix.
            """
            contents = contents or self.label
            if label_suffix is None:
                label_suffix = (self.field.label_suffix if self.field.label_suffix is not None
                                else self.form.label_suffix)
            # Only add the suffix if the label does not end in punctuation.
            # Translators: If found as last label character, these punctuation
            # characters will prevent the default label_suffix to be appended to the label
            if label_suffix and contents and contents[-1] not in _(':?.!'):
                contents = format_html('{}{}', contents, label_suffix)
            widget = self.field.widget
            id_ = widget.attrs.get('id') or self.auto_id
            if id_:
                id_for_label = widget.id_for_label(id_)
                if id_for_label:
                    attrs = dict(attrs or {}, **{'for': id_for_label})
                if self.field.required and hasattr(self.form, 'required_css_class'):
                    attrs = attrs or {}
                    if 'class' in attrs:
                        attrs['class'] += ' ' + self.form.required_css_class
                    else:
                        attrs['class'] = self.form.required_css_class
                attrs = flatatt(attrs) if attrs else ''
                contents = format_html('<label{}>{}</label>', attrs, contents)
            else:
                contents = conditional_escape(contents)
            return mark_safe(contents)

        def css_classes(self, extra_classes=None):
            """
            Returns a string of space-separated CSS classes for this field.
            """
            if hasattr(extra_classes, 'split'):
                extra_classes = extra_classes.split()
            extra_classes = set(extra_classes or [])
            if self.errors and hasattr(self.form, 'error_css_class'):
                extra_classes.add(self.form.error_css_class)
            if self.field.required and hasattr(self.form, 'required_css_class'):
                extra_classes.add(self.form.required_css_class)
            return ' '.join(extra_classes)

        @property
        def is_hidden(self):
            "Returns True if this BoundField's widget is hidden."
            return self.field.widget.is_hidden

        @property
        def auto_id(self):
            """
            Calculates and returns the ID attribute for this BoundField, if the
            associated Form has specified auto_id. Returns an empty string otherwise.
            """
            auto_id = self.form.auto_id
            if auto_id and '%s' in smart_text(auto_id):
                return smart_text(auto_id) % self.html_name
            elif auto_id:
                return self.html_name
            return ''

        @property
        def id_for_label(self):
            """
            Wrapper around the field widget's `id_for_label` method.
            Useful, for example, for focusing on this field regardless of whether
            it has a single widget or a MultiWidget.
            """
            widget = self.field.widget
            id_ = widget.attrs.get('id') or self.auto_id
            return widget.id_for_label(id_)