upload-data-to-table.py

import dash_html_components as html
import dash_core_components as dcc
import dash

import plotly
import dash_table_experiments as dte
from dash.dependencies import Input, Output, State

import pandas as pd
import numpy as np

import json
import datetime
import operator
import os

import base64
import io



app = dash.Dash()

app.scripts.config.serve_locally = True
app.config['suppress_callback_exceptions'] = True

app.layout = html.Div([

    html.H5("Upload Files"),
    dcc.Upload(
        id='upload-data',
        children=html.Div([
            'Drag and Drop or ',
            html.A('Select Files')
        ]),
        style={
            'width': '100%',
            'height': '60px',
            'lineHeight': '60px',
            'borderWidth': '1px',
            'borderStyle': 'dashed',
            'borderRadius': '5px',
            'textAlign': 'center',
            'margin': '10px'
        },
        multiple=False),
    html.Br(),
    html.Button(
        id='propagate-button',
        n_clicks=0,
        children='Propagate Table Data'
    ),


    html.Br(),
    html.H5("Filter Column"),
    dcc.Dropdown(id='dropdown_table_filterColumn',
        multi = False,
        placeholder='Filter Column'),


    html.Br(),
    html.H5("Updated Table"),
    html.Div(dte.DataTable(rows=[{}], id='table'))


])


# Functions

# file upload function
def parse_contents(contents, filename):
    content_type, content_string = contents.split(',')

    decoded = base64.b64decode(content_string)
    try:
        if 'csv' in filename:
            # Assume that the user uploaded a CSV file
            df = pd.read_csv(
                io.StringIO(decoded.decode('utf-8')))
        elif 'xls' in filename:
            # Assume that the user uploaded an excel file
            df = pd.read_excel(io.BytesIO(decoded))

    except Exception as e:
        print(e)
        return None

    return df


# callback table creation
@app.callback(Output('table', 'rows'),
              [Input('upload-data', 'contents'),
               Input('upload-data', 'filename')])
def update_output(contents, filename):
    if contents is not None:
        df = parse_contents(contents, filename)
        if df is not None:
            return df.to_dict('records')
        else:
            return [{}]
    else:
        return [{}]


#callback update options of filter dropdown
@app.callback(Output('dropdown_table_filterColumn', 'options'),
              [Input('propagate-button', 'n_clicks'),
               Input('table', 'rows')])
def update_filter_column_options(n_clicks_update, tablerows):
    if n_clicks_update < 1:
        print "df empty"
        return []

    else:
        dff = pd.DataFrame(tablerows) # <- problem! dff stays empty even though table was uploaded

        print "updating... dff empty?:", dff.empty #result is True, labels stay empty

        return [{'label': i, 'value': i} for i in sorted(list(dff))]


app.css.append_css({
    "external_url": "https://codepen.io/chriddyp/pen/bWLwgP.css"
})

if __name__ == '__main__':
    app.run_server(debug=True)