support dcc.send_file and dcc.send_data_frame

[Bernhard König]

This is a cross post from https://discourse.julialang.org/t/dash-jl-send-file-or-send-data-frame/63499

Is it correct, that dcc.send_data_frame and dcc.send_file are not supported yet.
I am trying to reproduce these examples in Julia
https://dash.plotly.com/dash-core-components/download

dcc.send_file seems most critical to me.

[Bernhard König]

turns out that for a DataFrame -> csv file, there is quite a simple workaround

callback!(app,
            Output("download-modelresult","data"),            
            Input("btn-download-model-results", "n_clicks"),
            prevent_initial_call = true
        ) do n_clicks
    
    df = DataFrames.DataFrame(a=rand(3),b=["a","b","xx"])
    csvrowwriteriterator = CSV.RowWriter(df)
    str = join(collect(csvrowwriteriterator))
    return Dict("filename"=>"miha.csv","content"=>str ,"base64"=>false)

end 

[Bernhard König]

similarly for any file on disk, this works for me

#send file from disk 
            file_from_disk = raw"c:\temp\temp.7z"
            #file_from_disk = raw"c:\temp\png1.png"
            rf = read(file_from_disk)
            io = IOBuffer()
            iob64_encode = Base64.Base64EncodePipe(io)
            write(iob64_encode,rf)
            close(iob64_encode)
            str = String(take!(io))
            #String(Base64.base64decode(str))
            fn = splitdir(file_from_disk)[2]
            return Dict("filename"=>fn,"content"=>str,"base64"=>true)