Callback for multivalue dropdown - plotly-dash

Question

I am pretty new to Plotly Dash and have been struggling especially with multivalue dropdown callback and would really appreciate any help. Basically I've followed a tutorial and created a pie-chart if a single pillar(from my data) value is selected. I would like to achieve two things:
The default or initial chart should show all pillar and the number of projects
Multi selection of pillar values
My main issue is actually the creating the callback for these. Thank you in advance for any help!!
Here is my code
app = dash.Dash(__name__)
all = df.Pillar.unique()
app.layout=html.Div([
html.H1("PM dashboard"),
dcc.Dropdown(id='pillar-choice',
options=[{'label':x, 'value':x}
for x in all],
value='Service Provider',
multi=False),
dcc.Graph(id='my-graph',
figure={}),
])
#app.callback(
Output(component_id='my-graph', component_property='figure'),
Input(component_id='pillar-choice', component_property='value')
)
def interactive_graphs(value_pillar):
print(value_pillar)
dff = df[df.Pillar==value_pillar]
fig = px.pie(data_frame=dff, names='Pillar', values='Project No')
return fig
if __name__=='__main__':
app.run_server()

Answer 1

I think the problem here is that value_pillar will be a list, so you need to do something like:
dff = df[df.Pillar.isin(value_pillar)]
And if you want to show everything by default, you'll need to check the value of that argument for your default value and, if it matches the default, avoid filtering.