forked from s434650/CatOrNot
191 lines
6.7 KiB
Python
191 lines
6.7 KiB
Python
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"""
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Useful form fields for use with SQLAlchemy ORM.
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"""
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from __future__ import unicode_literals
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import operator
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from wtforms import widgets
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from wtforms.compat import text_type, string_types
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from wtforms.fields import SelectFieldBase
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from wtforms.validators import ValidationError
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try:
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from sqlalchemy.orm.util import identity_key
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has_identity_key = True
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except ImportError:
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has_identity_key = False
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__all__ = (
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'QuerySelectField', 'QuerySelectMultipleField',
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)
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class QuerySelectField(SelectFieldBase):
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"""
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Will display a select drop-down field to choose between ORM results in a
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sqlalchemy `Query`. The `data` property actually will store/keep an ORM
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model instance, not the ID. Submitting a choice which is not in the query
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will result in a validation error.
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This field only works for queries on models whose primary key column(s)
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have a consistent string representation. This means it mostly only works
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for those composed of string, unicode, and integer types. For the most
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part, the primary keys will be auto-detected from the model, alternately
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pass a one-argument callable to `get_pk` which can return a unique
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comparable key.
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The `query` property on the field can be set from within a view to assign
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a query per-instance to the field. If the property is not set, the
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`query_factory` callable passed to the field constructor will be called to
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obtain a query.
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Specify `get_label` to customize the label associated with each option. If
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a string, this is the name of an attribute on the model object to use as
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the label text. If a one-argument callable, this callable will be passed
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model instance and expected to return the label text. Otherwise, the model
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object's `__str__` or `__unicode__` will be used.
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If `allow_blank` is set to `True`, then a blank choice will be added to the
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top of the list. Selecting this choice will result in the `data` property
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being `None`. The label for this blank choice can be set by specifying the
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`blank_text` parameter.
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"""
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widget = widgets.Select()
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def __init__(self, label=None, validators=None, query_factory=None,
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get_pk=None, get_label=None, allow_blank=False,
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blank_text='', **kwargs):
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super(QuerySelectField, self).__init__(label, validators, **kwargs)
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self.query_factory = query_factory
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if get_pk is None:
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if not has_identity_key:
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raise Exception('The sqlalchemy identity_key function could not be imported.')
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self.get_pk = get_pk_from_identity
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else:
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self.get_pk = get_pk
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if get_label is None:
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self.get_label = lambda x: x
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elif isinstance(get_label, string_types):
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self.get_label = operator.attrgetter(get_label)
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else:
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self.get_label = get_label
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self.allow_blank = allow_blank
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self.blank_text = blank_text
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self.query = None
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self._object_list = None
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def _get_data(self):
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if self._formdata is not None:
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for pk, obj in self._get_object_list():
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if pk == self._formdata:
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self._set_data(obj)
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break
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return self._data
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def _set_data(self, data):
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self._data = data
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self._formdata = None
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data = property(_get_data, _set_data)
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def _get_object_list(self):
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if self._object_list is None:
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query = self.query or self.query_factory()
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get_pk = self.get_pk
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self._object_list = list((text_type(get_pk(obj)), obj) for obj in query)
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return self._object_list
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def iter_choices(self):
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if self.allow_blank:
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yield ('__None', self.blank_text, self.data is None)
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for pk, obj in self._get_object_list():
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yield (pk, self.get_label(obj), obj == self.data)
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def process_formdata(self, valuelist):
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if valuelist:
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if self.allow_blank and valuelist[0] == '__None':
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self.data = None
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else:
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self._data = None
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self._formdata = valuelist[0]
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def pre_validate(self, form):
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data = self.data
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if data is not None:
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for pk, obj in self._get_object_list():
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if data == obj:
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break
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else:
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raise ValidationError(self.gettext('Not a valid choice'))
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elif self._formdata or not self.allow_blank:
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raise ValidationError(self.gettext('Not a valid choice'))
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class QuerySelectMultipleField(QuerySelectField):
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"""
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Very similar to QuerySelectField with the difference that this will
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display a multiple select. The data property will hold a list with ORM
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model instances and will be an empty list when no value is selected.
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If any of the items in the data list or submitted form data cannot be
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found in the query, this will result in a validation error.
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"""
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widget = widgets.Select(multiple=True)
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def __init__(self, label=None, validators=None, default=None, **kwargs):
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if default is None:
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default = []
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super(QuerySelectMultipleField, self).__init__(label, validators, default=default, **kwargs)
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if kwargs.get('allow_blank', False):
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import warnings
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warnings.warn('allow_blank=True does not do anything for QuerySelectMultipleField.')
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self._invalid_formdata = False
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def _get_data(self):
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formdata = self._formdata
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if formdata is not None:
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data = []
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for pk, obj in self._get_object_list():
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if not formdata:
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break
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elif pk in formdata:
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formdata.remove(pk)
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data.append(obj)
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if formdata:
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self._invalid_formdata = True
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self._set_data(data)
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return self._data
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def _set_data(self, data):
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self._data = data
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self._formdata = None
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data = property(_get_data, _set_data)
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def iter_choices(self):
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for pk, obj in self._get_object_list():
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yield (pk, self.get_label(obj), obj in self.data)
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def process_formdata(self, valuelist):
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self._formdata = set(valuelist)
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def pre_validate(self, form):
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if self._invalid_formdata:
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raise ValidationError(self.gettext('Not a valid choice'))
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elif self.data:
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obj_list = list(x[1] for x in self._get_object_list())
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for v in self.data:
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if v not in obj_list:
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raise ValidationError(self.gettext('Not a valid choice'))
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def get_pk_from_identity(obj):
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key = identity_key(instance=obj)[1]
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return ':'.join(text_type(x) for x in key)
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