unclear on dcc.Input type argument effect

[jwhendy]

I assumed that dcc.Input(..., type='number') would return the contents as an int or float. My request:

• if this is false and dcc.Input are always of type str, could this be made more clear in the docs?

• if this should be the case, could someone take a look at what's going on?

• in either case, could the docs be more clear about the effect of the type argument? At present it simply says "The type of control to render." I'm starting to suspect it only affects a minor appearance of the input box.

Thanks!

[jwhendy]

Per the comment over in #161, I looked at the html docs themselves and found this page on <input type="number"> elements.

I'm still a little confused, but think it's because js must do some automatic type conversion. For example, this:

<input type="text" id="myNumber" value="2">
function myFunction() {
    var x = document.getElementById("myNumber").value * 2;
    document.getElementById("demo").innerHTML = x;
}

still returned 4 even though it's set to type text and the value appears to be a string, "2".

So... I'm going to take it that in the dash context, dcc.Input will always return str. If that's the case, I think this can just be closed and I was wrong in my assumption. The type just gives a certain kind of input box tailored to what format its contents will be, but doesn't change what it returns.

[chriddyp]

This behaviour was actually changed in plotly/dash-core-components#100 as discussed in #124. The new behaviour is in the latest version of dash-core-components, released last sunday (https://github.com/plotly/dash-core-components/blob/master/CHANGELOG.md#changed)

[jwhendy]

Ha! What timing. Great news and good reminder to search/post issues in the right place (sorry about that). Also a good reminder to keep more up to date on my installs. Thanks!

[jwhendy]

Am I misunderstanding what that PR was supposed to do? I just took the example from #124 and simply added some version printing at the top, but I get what I'm assuming was @Madhu94 's intent to show how this shouldn't work?

## added to the top of that file:
print('dash: {}\ndcc: {}\nhtml: {}'.format(
    dash.__version__, dcc.__version__, html.__version__))

After changing the values from their initialized 0.7, I get:

Command line output:

$ python dash_issue_124.py
dash: 0.19.0
dcc: 0.15.0
html: 0.8.0

I just retried after pip install --user --upgrade git+https://github.com/plotly/dash-core-components.git and still get the same behavior.

[Madhu94]

@jwhendy Thanks for reporting the issue, I'll check this.

[chriddyp]

@Madhu94 @jwhendy - Thanks for reporting! Sorry about this - the build on 0.15.0 was bad. I've updated this on v0.15.2, so give this a try:

pip install dash-core-components==0.15.2

import dash
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash()

app.layout = html.Div([
    dcc.Input(id='input', type='number'),
    html.Div(id='output')
])


@app.callback(
    dash.dependencies.Output('output', 'children'),
    [dash.dependencies.Input('input', 'value')])
def update_output(value):
    print type(value)
    return value


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

[jwhendy]

Rockin! I just replicated @Madhu94 's example from #124 and it works like a charm now. Thanks for the quick fix!