Upload Component


The Dash upload component allows your app’s viewers to upload files,
like excel spreadsheets or images, into your application.
Your Dash app can access the contents of an upload by listening to
the contents property of the dcc.Upload
component.


contents is a base64 encoded string that contains the files contents,
no matter what type of file: text files, images, zip files,
excel spreadsheets, etc.


Here’s an example that parses CSV or Excel files and displays
the results in a table. Note that this example uses the
DataTable from the
dash-table
project.

import base64
import datetime
import io

import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
import dash_table

import pandas as pd

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    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'
        },
        # Allow multiple files to be uploaded
        multiple=True
    ),
    html.Div(id='output-data-upload'),
])

def parse_contents(contents, filename, date):
    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 html.Div([
            'There was an error processing this file.'
        ])

    return html.Div([
        html.H5(filename),
        html.H6(datetime.datetime.fromtimestamp(date)),

        dash_table.DataTable(
            data=df.to_dict('records'),
            columns=[{'name': i, 'id': i} for i in df.columns]
        ),

        html.Hr(),  # horizontal line

        # For debugging, display the raw contents provided by the web browser
        html.Div('Raw Content'),
        html.Pre(contents[0:200] + '...', style={
            'whiteSpace': 'pre-wrap',
            'wordBreak': 'break-all'
        })
    ])

@app.callback(Output('output-data-upload', 'children'),
              Input('upload-data', 'contents'),
              State('upload-data', 'filename'),
              State('upload-data', 'last_modified'))
def update_output(list_of_contents, list_of_names, list_of_dates):
    if list_of_contents is not None:
        children = [
            parse_contents(c, n, d) for c, n, d in
            zip(list_of_contents, list_of_names, list_of_dates)]
        return children

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

This next example responds to image uploads by displaying them
in the app with the html.Img component.

import datetime

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

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    dcc.Upload(
        id='upload-image',
        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'
        },
        # Allow multiple files to be uploaded
        multiple=True
    ),
    html.Div(id='output-image-upload'),
])

def parse_contents(contents, filename, date):
    return html.Div([
        html.H5(filename),
        html.H6(datetime.datetime.fromtimestamp(date)),

        # HTML images accept base64 encoded strings in the same format
        # that is supplied by the upload
        html.Img(src=contents),
        html.Hr(),
        html.Div('Raw Content'),
        html.Pre(contents[0:200] + '...', style={
            'whiteSpace': 'pre-wrap',
            'wordBreak': 'break-all'
        })
    ])

@app.callback(Output('output-image-upload', 'children'),
              Input('upload-image', 'contents'),
              State('upload-image', 'filename'),
              State('upload-image', 'last_modified'))
def update_output(list_of_contents, list_of_names, list_of_dates):
    if list_of_contents is not None:
        children = [
            parse_contents(c, n, d) for c, n, d in
            zip(list_of_contents, list_of_names, list_of_dates)]
        return children

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

The children attribute of the Upload component accepts any
Dash component. Clicking on the children element will trigger the
upload action, as will dragging and dropping files.
Here are a few different ways that you could style the upload
component using standard dash components.

import dash
import dash_core_components as dcc
import dash_html_components as html

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.layout = html.Div([
    dcc.Upload(html.Button('Upload File')),

    html.Hr(),

    dcc.Upload(html.A('Upload File')),

    html.Hr(),

    dcc.Upload([
        'Drag and Drop or ',
        html.A('Select a File')
    ], style={
        'width': '100%',
        'height': '60px',
        'lineHeight': '60px',
        'borderWidth': '1px',
        'borderStyle': 'dashed',
        'borderRadius': '5px',
        'textAlign': 'center'
    })
])

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



Upload Properties

Access this documentation in your Python terminal with:
```python

help(dash.dcc.Upload)
```

Our recommended IDE for writing Dash apps is Dash Enterprise’s
Data Science Workspaces,
which has typeahead support for Dash Component Properties.
Find out if your company is using
Dash Enterprise
.

children (a list of or a singular dash component, string or number | string; optional):
Contents of the upload component.

id (string; optional):
The ID of this component, used to identify dash components in
callbacks. The ID needs to be unique across all of the components
in an app.

accept (string; optional):
Allow specific types of files. See
https://github.com/okonet/attr-accept for more information. Keep
in mind that mime type determination is not reliable across
platforms. CSV files, for example, are reported as text/plain
under macOS but as application/vnd.ms-excel under Windows. In some
cases there might not be a mime type set at all. See:
https://github.com/react-dropzone/react-dropzone/issues/276.

className (string; optional):
HTML class name of the component.

className_active (string; optional):
HTML class name of the component while active.

className_disabled (string; optional):
HTML class name of the component if disabled.

className_reject (string; optional):
HTML class name of the component if rejected.

contents (string | list of strings; optional):
The contents of the uploaded file as a binary string.

disable_click (boolean; default False):
Disallow clicking on the component to open the file dialog.

disabled (boolean; default False):
Enable/disable the upload component entirely.

filename (string | list of strings; optional):
The name of the file(s) that was(were) uploaded. Note that this
does not include the path of the file (for security reasons).

last_modified (number | list of numbers; optional):
The last modified date of the file that was uploaded in unix time
(seconds since 1970).

loading_state (dict; optional):
Object that holds the loading state object coming from
dash-renderer.

loading_state is a dict with keys:

  • component_name (string; optional):
    Holds the name of the component that is loading.

  • is_loading (boolean; optional):
    Determines if the component is loading or not.

  • prop_name (string; optional):
    Holds which property is loading.

max_size (number; default -1):
Maximum file size in bytes. If -1, then infinite.

min_size (number; default 0):
Minimum file size in bytes.

multiple (boolean; default False):
Allow dropping multiple files.

style (dict; optional):
CSS styles to apply.

style_active (dict; default { borderStyle: 'solid', borderColor: '#6c6', backgroundColor: '#eee',}):
CSS styles to apply while active.

style_disabled (dict; default { opacity: 0.5,}):
CSS styles if disabled.

style_reject (dict; default { borderStyle: 'solid', borderColor: '#c66', backgroundColor: '#eee',}):
CSS styles if rejected.