Callbacks are not correctly checking to make sure the same output (id/property pair) is used only once

[daattali]

Even though the documentation claims that an output pair can only exist in one callback, and even though there seems to be code that attempts to make this check, this doesn't seem to actually hold true. For example, the following app defines the same callback 3 times with a slightly different return value, and it seems that the last one to be called is the one that sticks:

library(dash)

app <- dash_app()

app %>% set_layout(
  dccInput("text", "test"),
  div(id = "out")
)

app %>% add_callback(
  outputs = output("out", "children"),
  params = input("text", "value"),
  function(data) data
)

app %>% add_callback(
  outputs = output("out", "children"),
  params = input("text", "value"),
  function(data) paste(data, "2")
)

app %>% add_callback(
  outputs = output("out", "children"),
  params = input("text", "value"),
  function(data) paste(data, "3")
)

app %>% run_app()

[daattali]

@HammadTheOne is this fixed?

[HammadTheOne]

Yes, this should be fixed through #280. If the same id/prop pair is entered, this will now throw an error.

[daattali]

I just tested this and it still doesn't throw any message or error, are you sure it's fixed? Can you run it and confirm

[HammadTheOne]

I see this when running it off the latest dev branch version.

[daattali]

I may have not run dev, sorry. I'll confirm and close the issue