wtforms.ext.appengine.ndb — WTForms Documentation (2.3.x)

# Source code for wtforms.ext.appengine.ndb

    """
    Form generation utilities for App Engine's new ``ndb.Model`` class.

    The goal of ``model_form()`` is to provide a clean, explicit and predictable
    way to create forms based on ``ndb.Model`` classes. No malabarism or black
    magic should be necessary to generate a form for models, and to add custom
    non-model related fields: ``model_form()`` simply generates a form class
    that can be used as it is, or that can be extended directly or even be used
    to create other forms using ``model_form()``.

    Example usage:

    .. code-block:: python

       from google.appengine.ext import ndb
       from wtforms.ext.appengine.ndb import model_form

       # Define an example model and add a record.
       class Contact(ndb.Model):
           name = ndb.StringProperty(required=True)
           city = ndb.StringProperty()
           age = ndb.IntegerProperty(required=True)
           is_admin = ndb.BooleanProperty(default=False)

       new_entity = Contact(key_name='test', name='Test Name', age=17)
       new_entity.put()

       # Generate a form based on the model.
       ContactForm = model_form(Contact)

       # Get a form populated with entity data.
       entity = Contact.get_by_key_name('test')
       form = ContactForm(obj=entity)

    Properties from the model can be excluded from the generated form, or it can
    include just a set of properties. For example:

    .. code-block:: python

       # Generate a form based on the model, excluding 'city' and 'is_admin'.
       ContactForm = model_form(Contact, exclude=('city', 'is_admin'))

       # or...

       # Generate a form based on the model, only including 'name' and 'age'.
       ContactForm = model_form(Contact, only=('name', 'age'))

    The form can be generated setting field arguments:

    .. code-block:: python

       ContactForm = model_form(Contact, only=('name', 'age'), field_args={
           'name': {
               'label': 'Full name',
               'description': 'Your name',
           },
           'age': {
               'label': 'Age',
               'validators': [validators.NumberRange(min=14, max=99)],
           }
       })

    The class returned by ``model_form()`` can be used as a base class for forms
    mixing non-model fields and/or other model forms. For example:

    .. code-block:: python

       # Generate a form based on the model.
       BaseContactForm = model_form(Contact)

       # Generate a form based on other model.
       ExtraContactForm = model_form(MyOtherModel)

       class ContactForm(BaseContactForm):
           # Add an extra, non-model related field.
           subscribe_to_news = f.BooleanField()

           # Add the other model form as a subform.
           extra = f.FormField(ExtraContactForm)

    The class returned by ``model_form()`` can also extend an existing form
    class:

    .. code-block:: python

       class BaseContactForm(Form):
           # Add an extra, non-model related field.
           subscribe_to_news = f.BooleanField()

       # Generate a form based on the model.
       ContactForm = model_form(Contact, base_class=BaseContactForm)

    """
    from wtforms import Form, validators, fields as f
    from wtforms.compat import string_types
    from wtforms.ext.appengine.fields import GeoPtPropertyField, KeyPropertyField, StringListPropertyField, IntegerListPropertyField

    def get_TextField(kwargs):
        """
        Returns a ``TextField``, applying the ``ndb.StringProperty`` length limit
        of 500 bytes.
        """
        kwargs['validators'].append(validators.length(max=500))
        return f.TextField(**kwargs)

    def get_IntegerField(kwargs):
        """
        Returns an ``IntegerField``, applying the ``ndb.IntegerProperty`` range
        limits.
        """
        v = validators.NumberRange(min=-0x8000000000000000, max=0x7fffffffffffffff)
        kwargs['validators'].append(v)
        return f.IntegerField(**kwargs)

    class ModelConverterBase(object):
        def __init__(self, converters=None):
            """
            Constructs the converter, setting the converter callables.

            :param converters:
                A dictionary of converter callables for each property type. The
                callable must accept the arguments (model, prop, kwargs).
            """
            self.converters = {}

            for name in dir(self):
                if not name.startswith('convert_'):
                    continue
                self.converters[name[8:]] = getattr(self, name)

        def convert(self, model, prop, field_args):
            """
            Returns a form field for a single model property.

            :param model:
                The ``db.Model`` class that contains the property.
            :param prop:
                The model property: a ``db.Property`` instance.
            :param field_args:
                Optional keyword arguments to construct the field.
            """

            prop_type_name = type(prop).__name__

            # Check for generic property
            if(prop_type_name == "GenericProperty"):
                # Try to get type from field args
                generic_type = field_args.get("type")
                if generic_type:
                    prop_type_name = field_args.get("type")

                # If no type is found, the generic property uses string set in convert_GenericProperty

            kwargs = {
                'label': prop._code_name.replace('_', ' ').title(),
                'default': prop._default,
                'validators': [],
            }
            if field_args:
                kwargs.update(field_args)

            if prop._required and prop_type_name not in self.NO_AUTO_REQUIRED:
                kwargs['validators'].append(validators.required())

            if kwargs.get('choices', None):
                # Use choices in a select field.
                kwargs['choices'] = [(v, v) for v in kwargs.get('choices')]
                return f.SelectField(**kwargs)

            if prop._choices:
                # Use choices in a select field.
                kwargs['choices'] = [(v, v) for v in prop._choices]
                return f.SelectField(**kwargs)

            else:
                converter = self.converters.get(prop_type_name, None)
                if converter is not None:
                    return converter(model, prop, kwargs)
                else:
                    return self.fallback_converter(model, prop, kwargs)

    class ModelConverter(ModelConverterBase):
        """
        Converts properties from a ``ndb.Model`` class to form fields.

        Default conversions between properties and fields:

        +====================+===================+==============+==================+
        | Property subclass  | Field subclass    | datatype     | notes            |
        +====================+===================+==============+==================+
        | StringProperty     | TextField         | unicode      | TextArea         | repeated support
        |                    |                   |              | if multiline     |
        +--------------------+-------------------+--------------+------------------+
        | BooleanProperty    | BooleanField      | bool         |                  |
        +--------------------+-------------------+--------------+------------------+
        | IntegerProperty    | IntegerField      | int or long  |                  | repeated support
        +--------------------+-------------------+--------------+------------------+
        | FloatProperty      | TextField         | float        |                  |
        +--------------------+-------------------+--------------+------------------+
        | DateTimeProperty   | DateTimeField     | datetime     | skipped if       |
        |                    |                   |              | auto_now[_add]   |
        +--------------------+-------------------+--------------+------------------+
        | DateProperty       | DateField         | date         | skipped if       |
        |                    |                   |              | auto_now[_add]   |
        +--------------------+-------------------+--------------+------------------+
        | TimeProperty       | DateTimeField     | time         | skipped if       |
        |                    |                   |              | auto_now[_add]   |
        +--------------------+-------------------+--------------+------------------+
        | TextProperty       | TextAreaField     | unicode      |                  |
        +--------------------+-------------------+--------------+------------------+
        | GeoPtProperty      | TextField         | db.GeoPt     |                  |
        +--------------------+-------------------+--------------+------------------+
        | KeyProperty        | KeyProperyField   | ndb.Key      |                  |
        +--------------------+-------------------+--------------+------------------+
        | BlobKeyProperty    | None              | ndb.BlobKey  | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | UserProperty       | None              | users.User   | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | StructuredProperty | None              | ndb.Model    | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | LocalStructuredPro | None              | ndb.Model    | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | JsonProperty       | TextField         | unicode      |                  |
        +--------------------+-------------------+--------------+------------------+
        | PickleProperty     | None              | bytedata     | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | GenericProperty    | None              | generic      | always skipped   |
        +--------------------+-------------------+--------------+------------------+
        | ComputedProperty   | none              |              | always skipped   |
        +====================+===================+==============+==================+

        """
        # Don't automatically add a required validator for these properties
        NO_AUTO_REQUIRED = frozenset(['ListProperty', 'StringListProperty', 'BooleanProperty'])

        def convert_StringProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.StringProperty``."""
            if prop._repeated:
                return StringListPropertyField(**kwargs)
            kwargs['validators'].append(validators.length(max=500))
            return get_TextField(kwargs)

        def convert_BooleanProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.BooleanProperty``."""
            return f.BooleanField(**kwargs)

        def convert_IntegerProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.IntegerProperty``."""
            if prop._repeated:
                return IntegerListPropertyField(**kwargs)
            return get_IntegerField(kwargs)

        def convert_FloatProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.FloatProperty``."""
            return f.FloatField(**kwargs)

        def convert_DateTimeProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.DateTimeProperty``."""
            if prop._auto_now or prop._auto_now_add:
                return None

            return f.DateTimeField(format='%Y-%m-%d %H:%M:%S', **kwargs)

        def convert_DateProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.DateProperty``."""
            if prop._auto_now or prop._auto_now_add:
                return None

            return f.DateField(format='%Y-%m-%d', **kwargs)

        def convert_TimeProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.TimeProperty``."""
            if prop._auto_now or prop._auto_now_add:
                return None

            return f.DateTimeField(format='%H:%M:%S', **kwargs)

        def convert_RepeatedProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            return None

        def convert_UserProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.UserProperty``."""
            return None

        def convert_StructuredProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            return None

        def convert_LocalStructuredProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            return None

        def convert_JsonProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            return None

        def convert_PickleProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            return None

        def convert_GenericProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ListProperty``."""
            kwargs['validators'].append(validators.length(max=500))
            return get_TextField(kwargs)

        def convert_BlobKeyProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.BlobKeyProperty``."""
            return f.FileField(**kwargs)

        def convert_TextProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.TextProperty``."""
            return f.TextAreaField(**kwargs)

        def convert_ComputedProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.ComputedProperty``."""
            return None

        def convert_GeoPtProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.GeoPtProperty``."""
            return GeoPtPropertyField(**kwargs)

        def convert_KeyProperty(self, model, prop, kwargs):
            """Returns a form field for a ``ndb.KeyProperty``."""
            if 'reference_class' not in kwargs:
                try:
                    reference_class = prop._kind
                except AttributeError:
                    reference_class = prop._reference_class

                if isinstance(reference_class, string_types):
                    # reference class is a string, try to retrieve the model object.
                    mod = __import__(model.__module__, None, None, [reference_class], 0)
                    reference_class = getattr(mod, reference_class)
                kwargs['reference_class'] = reference_class
            kwargs.setdefault('allow_blank', not prop._required)
            return KeyPropertyField(**kwargs)

    def model_fields(model, only=None, exclude=None, field_args=None,
                     converter=None):
        """
        Extracts and returns a dictionary of form fields for a given
        ``db.Model`` class.

        :param model:
            The ``db.Model`` class to extract fields from.
        :param only:
            An optional iterable with the property names that should be included in
            the form. Only these properties will have fields.
        :param exclude:
            An optional iterable with the property names that should be excluded
            from the form. All other properties will have fields.
        :param field_args:
            An optional dictionary of field names mapping to a keyword arguments
            used to construct each field object.
        :param converter:
            A converter to generate the fields based on the model properties. If
            not set, ``ModelConverter`` is used.
        """
        converter = converter or ModelConverter()
        field_args = field_args or {}

        # Get the field names we want to include or exclude, starting with the
        # full list of model properties.
        props = model._properties
        field_names = list(x[0] for x in sorted(props.items(), key=lambda x: x[1]._creation_counter))

        if only:
            field_names = list(f for f in only if f in field_names)
        elif exclude:
            field_names = list(f for f in field_names if f not in exclude)

        # Create all fields.
        field_dict = {}
        for name in field_names:
            field = converter.convert(model, props[name], field_args.get(name))
            if field is not None:
                field_dict[name] = field

        return field_dict

    def model_form(model, base_class=Form, only=None, exclude=None, field_args=None,
                   converter=None):
        """
        Creates and returns a dynamic ``wtforms.Form`` class for a given
        ``ndb.Model`` class. The form class can be used as it is or serve as a base
        for extended form classes, which can then mix non-model related fields,
        subforms with other model forms, among other possibilities.

        :param model:
            The ``ndb.Model`` class to generate a form for.
        :param base_class:
            Base form class to extend from. Must be a ``wtforms.Form`` subclass.
        :param only:
            An optional iterable with the property names that should be included in
            the form. Only these properties will have fields.
        :param exclude:
            An optional iterable with the property names that should be excluded
            from the form. All other properties will have fields.
        :param field_args:
            An optional dictionary of field names mapping to keyword arguments
            used to construct each field object.
        :param converter:
            A converter to generate the fields based on the model properties. If
            not set, ``ModelConverter`` is used.
        """
        # Extract the fields from the model.
        field_dict = model_fields(model, only, exclude, field_args, converter)

        # Return a dynamically created form class, extending from base_class and
        # including the created fields as properties.
        return type(model._get_kind() + 'Form', (base_class,), field_dict)