stevej2608 / dash-spa

Dash Single Page Application (SPA) Framework

Dash/SPA is a minimal template and component suite that allows you to build complex Dash based multi-page applications with ease. The demo application includes several well known Dash demos that have been pasted into the SPA framework to show how easy it is to transition to SPA. Dash/SPA can be installed from pypi

pip install dash-spa

Demo

pip install -r requirements.txt
python usage.py

or:

python waitress_server.py

When you sign in to the demo app for the first time you will be asked to create an admin account. Enter any email address and password you fancy. To manage users, as admin, select Users from the My Account drop-down on the nav-bar.

Docker Demo Website

Perform the following steps to build and run the demo website in an nginx docker container.

Build demo website Docker image:

docker build -t holoniq/dash-spa .

Run website:

docker run -it --rm  -p 5000:80 holoniq/dash-spa

Visit http://localhost:5000/

If needed, to debug, run bash in the container:

docker run -it --rm  -p 5000:80 holoniq/dash-apa /bin/bash

Remove image:

docker rmi holoniq/dash-spa

Features

The following Dash/SPA features are implemented to allow Dash to be more easily used at scale.

Dash/SPA supports Flask style Blueprints and route decorators:

from dash import html
from dash_spa import Blueprint

greetings = Blueprint('greetings')

@greetings.route('/hello')
def hello():
    return html.H2('Dash/SPA says HELLO!')

@greetings.route('/goodby')
def goodby():
    return html.H2('Dash/SPA says GOODBY!')

...

app.register_blueprint(greetings, url_prefix='/test/greetings')

Dash/SPA manages component IDs using blueprint/route based namespaces. This greatly reduces Dash component ID conflicts. A component ID is only defined once when the component is created. It is then used by reference in associated Dash callbacks:

from dash import html
import dash_bootstrap_components as dbc
import dash_holoniq_components as dhc

user_name = dbc.Input(id='user', placeholder="Enter name")
password = dhc.PasswordInput("Password", name='password', id='password', placeholder="Enter password")

btn = html.Button('Enter', id='enter', disabled=True)

@app.callback(btn.output.disabled, [user_name.input.value, password.input.value])
def _cb_enter(user_name, password):
    return not db_validate_user(user_name, password)

Dash components created outside of a blueprint route are prefixed with the enclosing modules name (__NAME__)

Routes can be protected by an arbitrary access validation function:

@admin.route('/users', title='Admin Users', access=validate_user)
def user_view(ctx):
  pass

In the example, validate_user throws an exception if the user is not signed in. This results in a 404 page being displayed

Dash/SPA includes an optional NAVBAR, configured by a simple dictionary:

NAV_BAR_ITEMS = {
    'brand' : spa.NavbarBrand('Dash/SPA','/'),
    'left' : [
        spa.NavbarLink('Global Warming','/demo/warming'),
        spa.NavbarLink('State Solar', '/demo/solar'),
        spa.NavbarLink('Ticker', '/demo/ticker?tickers=COKE'),
        spa.NavbarLink('Profile', '/user/profile'),
        spa.NavbarLink('Admin', '/admin/users'),
    ],
    'right': [
        AdminNavbarComponent()
    ],

    'footer': spa.Footer('SPA/Examples'),
}

Dash/SPA Allows easy creation of interactive forms

frm = SpaForm(ctx,'loginFrm')

email = frm.Input('Email', name='email', type='email', placeholder="Enter email")
password = frm.PasswordInput("Password", name='password', placeholder="Enter password")
button = html.Button('Sign In', type='submit')

form = frm.Form([
    email,
    password,
    button,
], title='Sign In'),


@app.callback(form.output.children, [form.input.form_data])
def _form_submit(values):
    print(values)
    return spa.NOUPDATE

Examples

multipage.py

An example of a multi-page app with navbar and footer in less than sixty lines of code.

    python -m examples.multipage

Then visit http://localhost:8050/demo/page1

checkbox table row selection

    python -m examples.table

Then visit http://localhost:8050/table/page1

Admin Blueprint

Dash/SPA Includes an optional admin blueprint that supports user registration, email authentication and login. This is provided as a demonstrator, careful consideration to the security implications should be undertaken before using it in a public website.

Views are provided that allow:

• Register, name, email, password. Verification code send by email.

• Enter the email verification code.

• Normal user login.

• Reset forgotten password, Password reset code sent by email.

• Enter password reset code.

• Enter new password, confirm new password.

• Login using new password.

• User admin table with Add, Edit and Delete. Accessible only when signed in with admin rights.

User DB

User details are held in a local sqlite db. The SQLAlchemy model and all DB interaction is defined in login_manager.py. It should be straight forward to modify this for other databases.

Authentication mailer

The authentication mailer is configured in settings.py this will need to be modified to include the details for your email agent, see below.

If you use gmail just change the user/password details in the gmail options. To use a specific mailer edit the mail_options.active field. Emails sent by the mailer will have come from mail_options.sender edit this field as required. Gmail will flag unknown emails as a security risk.

Configuration

Configuration details are held in the settings.py. The environmental variable FLASK_ENV can be configured to instruct Dash/SPA to use a different configuration.

Setting:

    FLASK_ENV='production'

Will use class ProdConfig: from settings.py. An example configuration is shown below:

class DefaultConfig(object):
    """Base configuration."""

    flask = {
        "SECRET_KEY": "my secret flask password",
        "URL_PREFIX": "api"
    }

    logging = {"level": "INFO"}

    user_db = {
        "database_uri": "sqlite:///db.sqlite"
    }
    mail_options = {
        "sender": "[email protected]",
        "active": "gmail",
        "gmail": {
            "host": "smtp.gmail.com",
            "port": 465,
            "secure": True,
            "auth": {
                "user": "[email protected]",
                "password": "bigjoepassword"
            }
        },
        "plusnet": {
            "host": "relay.plus.net",
            "port": 587,
            "secure": False,
            "auth": {
                "user": "bigjoe",
                "password": "bigjoesotherpassword"
            }
        }
    }


class ProdConfig(DefaultConfig):
    """Production configuration."""


class DevConfig(DefaultConfig):
    """Development configuration."""


class TestConfig(DefaultConfig):
    """Test configuration."""

    flask = {
        "SECRET_KEY": "my secret flask password",
        "URL_PREFIX": "api",
        "FLASK_ENV" : "test"
    }

    user_db = {
        "database_uri": "sqlite:///tests/admin/test_db.sqlite"
    }

    logging = {"level": "WARN"}

Build the project

The dash-spa package is available on pypi. If needed, to create a local tarball, first change the release version in dash_spa/_version.py, then:

rm -rf dist dash_spa.egg-info build

python setup.py sdist bdist_wheel

The tarball is in dist/dash_spa-.tar.gz

To install the tarball in a dash project:

pip install dash_spa-<version>.tar.gz

Testing

Pytest and Dash Duo are used for testing. To run these tests both the Chrome browser and Chrome driver must be installed. These are already installed in the VSCode Docker container. If you are not using remote containers you must install them first.

To run the tests:

pytest

Publish

twine upload dist/*