# Τεκμηρίωση του Django - 1.10.7

# Πηγαίος κώδικας για το django.contrib.postgres.forms.array

    import copy
    from itertools import chain

    from django import forms
    from django.contrib.postgres.validators import (
        ArrayMaxLengthValidator, ArrayMinLengthValidator,
    )
    from django.core.exceptions import ValidationError
    from django.utils import six
    from django.utils.safestring import mark_safe
    from django.utils.translation import ugettext_lazy as _

    from ..utils import prefix_validation_error

    class SimpleArrayField(forms.CharField):
        default_error_messages = {
            'item_invalid': _('Item %(nth)s in the array did not validate: '),
        }

        def __init__(self, base_field, delimiter=',', max_length=None, min_length=None, *args, **kwargs):
            self.base_field = base_field
            self.delimiter = delimiter
            super(SimpleArrayField, self).__init__(*args, **kwargs)
            if min_length is not None:
                self.min_length = min_length
                self.validators.append(ArrayMinLengthValidator(int(min_length)))
            if max_length is not None:
                self.max_length = max_length
                self.validators.append(ArrayMaxLengthValidator(int(max_length)))

        def prepare_value(self, value):
            if isinstance(value, list):
                return self.delimiter.join(six.text_type(self.base_field.prepare_value(v)) for v in value)
            return value

        def to_python(self, value):
            if value:
                items = value.split(self.delimiter)
            else:
                items = []
            errors = []
            values = []
            for index, item in enumerate(items):
                try:
                    values.append(self.base_field.to_python(item))
                except ValidationError as error:
                    errors.append(prefix_validation_error(
                        error,
                        prefix=self.error_messages['item_invalid'],
                        code='item_invalid',
                        params={'nth': index},
                    ))
            if errors:
                raise ValidationError(errors)
            return values

        def validate(self, value):
            super(SimpleArrayField, self).validate(value)
            errors = []
            for index, item in enumerate(value):
                try:
                    self.base_field.validate(item)
                except ValidationError as error:
                    errors.append(prefix_validation_error(
                        error,
                        prefix=self.error_messages['item_invalid'],
                        code='item_invalid',
                        params={'nth': index},
                    ))
            if errors:
                raise ValidationError(errors)

        def run_validators(self, value):
            super(SimpleArrayField, self).run_validators(value)
            errors = []
            for index, item in enumerate(value):
                try:
                    self.base_field.run_validators(item)
                except ValidationError as error:
                    errors.append(prefix_validation_error(
                        error,
                        prefix=self.error_messages['item_invalid'],
                        code='item_invalid',
                        params={'nth': index},
                    ))
            if errors:
                raise ValidationError(errors)

    class SplitArrayWidget(forms.Widget):

        def __init__(self, widget, size, **kwargs):
            self.widget = widget() if isinstance(widget, type) else widget
            self.size = size
            super(SplitArrayWidget, self).__init__(**kwargs)

        @property
        def is_hidden(self):
            return self.widget.is_hidden

        def value_from_datadict(self, data, files, name):
            return [self.widget.value_from_datadict(data, files, '%s_%s' % (name, index))
                    for index in range(self.size)]

        def value_omitted_from_data(self, data, files, name):
            return all(
                self.widget.value_omitted_from_data(data, files, '%s_%s' % (name, index))
                for index in range(self.size)
            )

        def id_for_label(self, id_):
            # See the comment for RadioSelect.id_for_label()
            if id_:
                id_ += '_0'
            return id_

        def render(self, name, value, attrs=None):
            if self.is_localized:
                self.widget.is_localized = self.is_localized
            value = value or []
            output = []
            final_attrs = self.build_attrs(attrs)
            id_ = final_attrs.get('id')
            for i in range(max(len(value), self.size)):
                try:
                    widget_value = value[i]
                except IndexError:
                    widget_value = None
                if id_:
                    final_attrs = dict(final_attrs, id='%s_%s' % (id_, i))
                output.append(self.widget.render(name + '_%s' % i, widget_value, final_attrs))
            return mark_safe(self.format_output(output))

        def format_output(self, rendered_widgets):
            return ''.join(rendered_widgets)

        @property
        def media(self):
            return self.widget.media

        def __deepcopy__(self, memo):
            obj = super(SplitArrayWidget, self).__deepcopy__(memo)
            obj.widget = copy.deepcopy(self.widget)
            return obj

        @property
        def needs_multipart_form(self):
            return self.widget.needs_multipart_form

    class SplitArrayField(forms.Field):
        default_error_messages = {
            'item_invalid': _('Item %(nth)s in the array did not validate: '),
        }

        def __init__(self, base_field, size, remove_trailing_nulls=False, **kwargs):
            self.base_field = base_field
            self.size = size
            self.remove_trailing_nulls = remove_trailing_nulls
            widget = SplitArrayWidget(widget=base_field.widget, size=size)
            kwargs.setdefault('widget', widget)
            super(SplitArrayField, self).__init__(**kwargs)

        def clean(self, value):
            cleaned_data = []
            errors = []
            if not any(value) and self.required:
                raise ValidationError(self.error_messages['required'])
            max_size = max(self.size, len(value))
            for index in range(max_size):
                item = value[index]
                try:
                    cleaned_data.append(self.base_field.clean(item))
                except ValidationError as error:
                    errors.append(prefix_validation_error(
                        error,
                        self.error_messages['item_invalid'],
                        code='item_invalid',
                        params={'nth': index},
                    ))
                    cleaned_data.append(None)
                else:
                    errors.append(None)
            if self.remove_trailing_nulls:
                null_index = None
                for i, value in reversed(list(enumerate(cleaned_data))):
                    if value in self.base_field.empty_values:
                        null_index = i
                    else:
                        break
                if null_index is not None:
                    cleaned_data = cleaned_data[:null_index]
                    errors = errors[:null_index]
            errors = list(filter(None, errors))
            if errors:
                raise ValidationError(list(chain.from_iterable(errors)))
            return cleaned_data