Hi everyone ! 

On a card in Decker I have a function who is trying to toggle a boolean value in a "state" column in the grid  named "tasks". I just don’t understand why the function is not working… I think I don’t undersand something about types or queries. I tried so many options… I think there is something that I’m missing…

on toogle tid do
  # get the state value of the line with id=tid
  v:tasks.value[id=tid].state
  # toogle the value
  v: if v=1 0 else 1 end
  # update the grid with the correct value
 tasks.value:update state:v where id=tid from tasks.value
end

Given an integer id "tid" and a grid named "tasks" with numeric columns "id" and "state", you should be able to toggle a state cell like so:

tasks.value:update state:!state where id=tid from tasks.value

If you're seeing odd behavior, I'd recommend confirming that the "state" and "id" columns of your grid actually contain numbers, and not strings; you can see this distinction more easily if you inspect the table via the listener; strings in cells will be enclosed in double-quotes:

If you set the grid's format string appropriately, (in the above example "isi" for an integer column, a string column, and an integer column) you can "re-normalize" the data in a grid by toggling between JSON and CSV editing mode in the grid's properties dialog.

It may be a little surprising that negating the string "0" with ! produces the number 0, instead of 1, but this is because ! is not an arithmetic operator, it is a logical one, and all non-empty strings are considered "truthy" in Lil:

!(nil,"","0","1",0,1)
# (1,1,0,0,1,0)

If you're ever wanting the logical negation of a grid column that may contain "0"/"1" strings, you could also resolve the issue by adding zero to the string first, coercing it to a number:

0+(nil,"","0","1",0,1)
# (0,0,0,1,0,1)
!0+(nil,"","0","1",0,1)
# (1,1,1,0,1,0)

Or, in this context,

tasks.value:update state:!0+state where id=tid from tasks.value

Does that help?

As always your answer is absolutely perfect and helps to understand Lil and Decker in the right way. Your help is priceless! thank you again!