Creating a Webapp to Fetch API Information and Create Visualizations with Existing Data

LChillemi

I've been recently attempting at length to create a WebApp inside the Cloud Platform to fetch data from a project and create interactible visualizations. The original plan was to fetch existing Insight graphics and replicate them, but that had largely failed. There is no reliable API tool to fetch Insights from a project. I continued attempting with existing tools in the Webapp toolset, only to find it severely limited on cloud.

R/Shiny is non-functional in Cloud, and this has to be DSS Cloud for several internal reasons. It simply doesn't work, and there is no ETA for when it'll work. The standard webapp format does not carry all the tools necessary, as even getting plotly it doesn't correctly seem to display them most of the time.

I attempted using Dash, and had gotten somewhat far in that implementation. With the code below, I was able to create selectors that fetched the data of different columns in a list of datasets and created a graph based on the columns, but it was failing to update.

I was about to fix this, when Dash has simply stopped functioning. The backend no longer activates properly. Does anyone know why that is happening?

Code:

import dataiku
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
from dash.exceptions import PreventUpdate

# use the style of examples on the Plotly documentation
app.config.external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

# url, root-url and first-loading are used for routing
url_bar_and_content_div = html.Div([
    dcc.Location(id='url', refresh=False),
    html.Div(id='root-url', style={'display': 'none'}),
    html.Div(id='first-loading', style={'display': 'none'}),
    html.Div(id='page-content')
])

layout_index = html.Div([
    dcc.Link('Navigate to "page-1"', href='page-1'),
    html.Br(),
    dcc.Link('Navigate to "page-2"', href='page-2'),
])

layout_page_1 = html.Div([
    html.H2('Page 1'),
    dcc.Input(id='input-1-state', type='text', value='Montreal'),
    dcc.Input(id='input-2-state', type='text', value='Canada'),
    html.Button(id='submit-button', n_clicks=0, children='Submit'),
    html.Div(id='output-state'),
    html.Br(),
    dcc.Link('Navigate to "/"', id='page-1-root-link', href=''),
    html.Br(),
    dcc.Link('Navigate to "/page-2"', href='page-2'),
])

layout_page_2 = html.Div([
    html.H2('Page 2'),
    dcc.Dropdown(
        id='page-2-dropdown',
        options=[{'label': i, 'value': i} for i in ['LA', 'NYC', 'MTL']],
        value='LA'
    ),
    html.Div(id='page-2-display-value'),
    html.Br(),
    dcc.Link('Navigate to "/"', id='page-2-root-link', href=''),
    html.Br(),
    dcc.Link('Navigate to "/page-1"', href='page-1'),
])

# index layout
app.layout = url_bar_and_content_div

# "complete" layout, need at least Dash 1.12
app.validation_layout = html.Div([
    url_bar_and_content_div,
    layout_index,
    layout_page_1,
    layout_page_2,
])

# The following callback is used to dynamically instantiate the root-url
app.callback([dash.dependencies.Output('root-url', 'children'), dash.dependencies.Output('first-loading', 'children')],
              dash.dependencies.Input('url', 'pathname'),
              dash.dependencies.State('first-loading', 'children')
              )
def update_root_url(pathname, first_loading):
    if first_loading is None:
        return pathname, True
    else:
        raise PreventUpdate

# We can now use the hidden root-url div to update the link in page-1 and page-2
app.callback(dash.dependencies.Output('page-1-root-link', 'href'),
              [dash.dependencies.Input('root-url', 'children')])
def update_root_link(root_url):
    return root_url

@app.callback(dash.dependencies.Output('page-2-root-link', 'href'),
              [dash.dependencies.Input('root-url', 'children')])
def update_root_link(root_url):
    return root_url

# This is the callback doing the routing
app.callback(dash.dependencies.Output('page-content', 'children'),
              [
                  dash.dependencies.Input('root-url', 'children'),
                  dash.dependencies.Input('url', 'pathname')
              ])
def display_page(root_url, pathname):
    if root_url + "page-1" == pathname :
        return layout_page_1
    elif root_url + "page-2" == pathname :
        return layout_page_2
    else:
        return layout_index

# Page 1 callbacks
app.callback(Output('output-state', 'children'),
              [Input('submit-button', 'n_clicks')],
              [State('input-1-state', 'value'),
               State('input-2-state', 'value')])
def update_output(n_clicks, input1, input2):
    return ('The Button has been pressed {} times,'
            'Input 1 is "{}",'
            'and Input 2 is "{}"').format(n_clicks, input1, input2)


# Page 2 callbacks
app.callback(Output('page-2-display-value', 'children'),
              [Input('page-2-dropdown', 'value')])
def display_value(value):
    print('display_value')
    return 'You have selected "{}"'.format(value)

---

Operating system used: Windows

VitaliyD

Hi,

I have tried your code in my lab, and it works for me. The Webapp's log should point to the issue, so if you still need help identifying the backend failure's cause, please provide the logs.

Best,

Vitaliy