Source code for wtforms_sqlalchemy.fields

"""
Useful form fields for use with SQLAlchemy ORM.
"""
import operator

from wtforms import widgets
from wtforms.fields import SelectFieldBase
from wtforms.validators import ValidationError

try:
    from sqlalchemy.orm.util import identity_key

    has_identity_key = True
except ImportError:
    has_identity_key = False


__all__ = (
    "QuerySelectField",
    "QuerySelectMultipleField",
    "QueryRadioField",
    "QueryCheckboxField",
)


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