API¶

Core¶

View logic is often repetitive, there are standard patterns we repeat over again both within and across projects, and reimplementing the same patterns can be a bore.

These views take some of those patterns and abstract them so you can create views for common tasks quickly without having to write too much code.

Tasks such as rendering a template or redirecting to a new url can be performed by passing parameters at instantiation without defining additional classes.

Views¶

class flask_generic_views.core.View(**kwargs)¶

Bases: flask.views.View

The master class-based base view.

All other generic views inherit from this base class. This class itself inherits from flask.views.View and adds a generic constructor, that will convert any keyword arguments to instance attributes.

class GreetingView(View):
    greeting = 'Hello'

    def dispatch_request(self):
        return "{} World!".format(self.greeting)

bonjour_view = GreetingView.as_view('bonjour', greeting='Bonjour')

app.add_url_rule('/bonjour, view_func=bonjour_view)

The above example shows a generic view that allows us to change the greeting while setting up the URL rule.

class flask_generic_views.core.MethodView(**kwargs)¶

Bases: flask.views.MethodView, flask_generic_views.core.View

View class that routes to methods based on HTTP verb.

This view allows us to break down logic based on the HTTP verb used, and avoid conditionals in our code.

class GreetingView(View):
    greeting = 'Hello'

    def get(self):
        return "{} World!".format(self.greeting)

    def post(self):
        name = request.form.get('name', 'World')

        return "{} {}!".format(self.greeting, name)

bonjour_view = GreetingView.as_view('bonjour', greeting='Bonjour')

app.add_url_rule('/bonjour, view_func=bonjour_view)

The above example will process the request differently depending on wether it was a HTTP POST or GET.

class flask_generic_views.core.TemplateView(**kwargs)¶

Bases: flask_generic_views.core.TemplateResponseMixin, flask_generic_views.core.ContextMixin, flask_generic_views.core.MethodView

Renders a given template, with the context containing parameters captured by the URL rule.

class AboutView(View):
    template_name = 'about.html'

    def get_context_data(self, **kwargs):
        kwargs['staff'] = ('John Smith', 'Jane Doe')

        return super(AboutView, self).get_context_data(self, **kwargs)

app.add_url_rule('/about', view_func=AboutView.as_view('about'))

The TemplateView can be subclassed to create custom views that render a template.

about_view = TemplateView.as_view('about', template_name='about.html')

app.add_url_rule('/about', view_func=about_view,  defaults={
    'staff': ('John Smith', 'Jane Doe')
})

It can also be used directly in a URL rule to avoid having to create additional classes.

get(**kwargs)¶

Handle request and return a template response.

Any keyword arguments will be passed to the views context.

Parameters:	kwargs (dict) – keyword arguments from url rule
Returns:	response
Return type:	werkzeug.wrappers.Response

class flask_generic_views.core.RedirectView(**kwargs)¶

Bases: flask_generic_views.core.View

Redirects to a given URL.

The given URL may contain dictionary-style format fields which will be interpolated against the keyword arguments captured from the URL rule using the format() method.

An URL rule endpoint may be given instead, which will be passed to url_for() along with any keyword arguments captured by the URL rule.

When no URL can be found a Gone exception will be raised.

class ShortView(RedirectView):

    permanent = True
    query_string = True
    endpoint = 'post-detail'

    def get_redirect_url(self, **kwargs):
        post = Post.query.get_or_404(base62.decode(kwargs['code']))
        kwargs['slug'] = post.slug
        return super(ShortView, self).get_redirect_url(**kwargs)

   short_view = ShortView.as_view('short')

   app.add_url_rule('/s/<code>', view_func=short_view)

The above example will redirect “short links” where the pk is base62 encoded to the correct url.

google_view = RedirectView.as_view('google', url='http://google.com/')

app.add_url_rule('/google', view_func=google_view)

It can also be used directly in a URL rule to avoid having to create additional classes for simple redirects.

url = None¶: String containing the URL to redirect to or None to raise a Gone exception.

endpoint = None¶: The name of the endpoint to redirect to. URL generation will be done using the same keyword arguments as are passed in for this view.

permanent = False¶: Whether the redirect should be permanent. The only difference here is the HTTP status code returned. When True, then the redirect will use status code 301. When False, then the redirect will use status code 302.

query_string = False¶: Whether to pass along the query string to the new location. When True, then the query string is appended to the URL. When False, then the query string is discarded.

dispatch_request(**kwargs)¶

Redirect the user to the result of.

get_redirect_url(), when by default it will issue a 302 temporary redirect, except when permanent is set to the True, then a 301 permanent redirect will be used.

When the redirect URL is None, a Gone exception will be raised.

Any keyword arguments will be used to build the URL.

Parameters:	kwargs (dict) – keyword arguments from url rule
Returns:	response
Return type:	werkzeug.wrappers.Response

get_redirect_url(**kwargs)¶

Retrieve URL to redirect to.

When url is not None then it is returned after being interpolated with the keyword arguments using format().

When url is None and endpoint is not None then it is passed to url_for() with the keyword arguments, and any query string is removed.

The query string from the current request can be added to the new URL by setting query_string to True.

Parameters:	kwargs (dict) – keyword arguments
Returns:	URL
Return type:	str

class flask_generic_views.core.FormView(**kwargs)¶

Bases: flask_generic_views.core.TemplateResponseMixin, flask_generic_views.core.BaseFormView

View class to display a Form. When invalid it shows the form with validation errors, when valid it redirects to a new URL.

class ContactForm(Form):
    email = StringField('Name', [required(), email()])
    message = TextAreaField('Message', [required()])


class ContactView(FormView):
    form_class = ContactForm
    success_url = '/thanks'
    template_name = 'contact.html'

    def form_valid(self, form):
        message = Message('Contact Form', body=form.message.data,
                          recipients=['contact@example.com'],
                          sender=form.email.data)

        mail.send(message)

        super(ContactView).form_valid(form)

The above example will render the template contact.html with an instance of ContactForm in the context variable view, when the user submits the form with valid data an email will be sent, and the user redirected to /thanks, when the form is submitted with invalid data content.html will be rendered again, and the form will contain any error messages.

Helpers¶

class flask_generic_views.core.ContextMixin¶

Bases: object

Default handling of view context data any mixins that modifies the views context data should inherit from this class.

class RandomMixin(ContextMixin):
    def get_context_data(self, **kwargs):
        kwargs.setdefault('number', random.randrange(1, 100))

        return super(RandomMixin, self).get_context_data(**kwargs)

get_context_data(**kwargs)¶

Returns a dictionary representing the view context. Any keyword arguments provided will be included in the returned context.

The context of all class-based views will include a view variable that points to the View instance.

Parameters:	kwargs (dict) – context
Returns:	context
Return type:	dict

class flask_generic_views.core.TemplateResponseMixin¶

Bases: object

Creates Response instances with a rendered template based on the given context. The choice of template is configurable and can be customised by subclasses.

class RandomView(TemplateResponseMixin, MethodView):
    template_name = 'random.html'

    def get(self):
        context = {'number': random.randrange(1, 100)}
        return self.create_response(context)

random_view = RandomView.as_view('random')

app.add_url_rule('/random, view_func=random_view)

mimetype = None¶: The mime type type to use for the response. The mimetype is passed as a keyword argument to response_class.

response_class = flask.Response¶: The Response class to be returned by create_response().

template_name = None¶: The string containing the full name of the template to use. Not defining template_name will cause the default implementation of get_template_names() to raise a NotImplementedError exception.

create_response(context=None, **kwargs)¶

Returns a response_class instance containing the rendered template.

If any keyword arguments are provided, they will be passed to the constructor of the response class.

Parameters:	context (dict) – context for template kwargs (dict) – response keyword arguments
Returns:	response
Return type:	werkzeug.wrappers.Response

get_template_list()¶

Returns a list of template names to use for when rendering the template.

The default implementation will return a list containing template_name, when not specified a NotImplementedError exception will be raised.

Returns:	template list
Return type:	list
Raises:	NotImplementedError – when `template_name` is not set

class flask_generic_views.core.FormMixin¶

Bases: flask_generic_views.core.ContextMixin

Provides facilities for creating and displaying forms.

data = {}¶: A dictionary containing initial data for the form.

form_class = None¶: The form class to instantiate.

success_url = None¶: The URL to redirect to when the form is successfully processed.

prefix = ''¶: The prefix for the generated form.

form_invalid(form)¶

Creates a response using the return value of.

get_context_data().

Parameters:	form (flask_wtf.Form) – form instance
Returns:	response
Return type:	werkzeug.wrappers.Response

form_valid(form)¶

Redirects to get_success_url().

Parameters:	form (flask_wtf.Form) – form instance
Returns:	response
Return type:	werkzeug.wrappers.Response

get_context_data(**kwargs)¶

Extends the view context with a form variable containing the return value of get_form().

Parameters:	kwargs (dict) – context
Returns:	context
Return type:	dict

get_data()¶

Retrieve data to pass to the form.

By default returns a copy of data.

Returns:	data
Return type:	dict

get_form()¶

Create a Form instance using get_form_class() using get_form_kwargs().

Returns:	form
Return type:	flask_wtf.Form

get_form_class()¶

Retrieve the form class to instantiate.

By default returns form_class.

Returns:	form class
Return type:	type
Raises:	NotImplementedError – when `form_class` is not set

get_form_kwargs()¶

Retrieve the keyword arguments required to instantiate the form.

The data argument is set using get_data() and the prefix argument is set using get_prefix(). When the request is a POST or PUT, then the formdata argument will be set using get_formdata().

Returns:	keyword arguments
Return type:	dict

get_formdata()¶

Retrieve prefix to pass to the form.

By default returns a werkzeug.datastructures.CombinedMultiDict containing flask.request.form and flask.request.files.

Returns:	form / file data
Return type:	werkzeug.datastructures.CombinedMultiDict

get_prefix()¶

Retrieve prefix to pass to the form.

By default returns prefix.

Returns:	prefix
Return type:	str

get_success_url()¶

Retrive the URL to redirect to when the form is successfully validated.

By default returns success_url.

Returns:	URL
Return type:	str
Raises:	NotImplementedError – when `success_url` is not set

class flask_generic_views.core.ProcessFormView(**kwargs)¶

Bases: flask_generic_views.core.MethodView

Provides basic HTTP GET and POST processing for forms.

This class cannot be used directly and should be used with a suitable mixin.

get(**kwargs)¶

Creates a response using the return value of.

get_context_data().

Parameters:	kwargs (dict) – keyword arguments from url rule
Returns:	response
Return type:	werkzeug.wrappers.Response

post(**kwargs)¶

Constructs and validates a form.

When the form is valid form_valid() is called, when the form is invalid form_invalid() is called.

Parameters:	kwargs (dict) – keyword arguments from url rule
Returns:	response
Return type:	werkzeug.wrappers.Response

put(**kwargs)¶

Passes all keyword arguments to post().

Parameters:	kwargs (dict) – keyword arguments from url rule
Returns:	response
Return type:	werkzeug.wrappers.Response

class flask_generic_views.core.BaseFormView(**kwargs)¶

Bases: flask_generic_views.core.FormMixin, flask_generic_views.core.ProcessFormView

View class to process handle forms without response creation.

SQLAlchemy¶

Views logic often relates to retrieving and persisting data in a database, these views cover some of the most common patterns for working with models using the SQLAlchemy library.

Tasks such as displaying, listing, creating, updating, and deleting objects can be performed by passing parameters at instantiation without defining additional classes.

Views¶

Helpers¶

flask_generic_views.sqlalchemy.session¶: A proxy to the current SQLAlchemy session provided by Flask-SQLAlchemy.