We will take as our starting point a stack set up with a field with csv data in it, as described in the lesson How do I rename the headers on a text file? Add another button to the interface and name it "export":

Exporting our data will be quite similar to importing with a couple of changes. We will use the ask file command, instead of answer file, as this allows the user to provide the name and location of a new file or choose an existing file. We also want to ensure that we save out as a csv file so we check the file extension of the selected file.

on mouseUp
   local tFileName, tFileContents
   ask file "Please choose a where you want to save the file" with type "Comma Separated Values|csv|TEXT"
   if the result is not "cancel" then
      put it into tFileName
      ## Ensure the file extension is csv
      set the itemDel to "."
      if item 2 of tFileName is not "csv" then
         put "csv" into item 2 of tFileName
      end if
   end if
end mouseUp

As before we now have the location of the file we want to save our csv data into, all we have to do now is put the contents of the field into the file. Again we use the URL keyword, but this time we put the data into the url.

## Save the data out to file
put field "text" into tFileContents
put tFileContents into URL ("file:" & tFileName)

In the How do I rename the headers on a text file? lesson we imported our data and displayed it in a data grid. What if we want to export from a data grid? Again we can use the same LiveCode to get the file name, we just need to modify the LiveCode that saves the data.

Firstly we need to get the names of our columns, we get the data grid columns property, this is a line delimited list so we need to replace the item separators with commas:

put the dgProp[ "columns" ]  of group "text" into tColumnTitles
replace return with comma in tColumnTitles

Next we need the data, we get the dgText of the data grid, the item separator for dgText is tab so we replace tabs with commas as our output is to be comma separated:

put the dgText  of group "text" into tData
replace tab with comma in tData

Now we just need to save out titles and data to file:

put tColumnTitles & return & tData into URL ("file:" & tFileName)