parse csv using lua script

Question

I have a csv file that has data like this:

+12345678901,08:00:00,12:00:00,1111100,35703,test.domain.net
+12345678901,,,0000000,212,test.domain.net

I'm trying to write lua code that will loop through each line, and create an array of values like this:

local mylist = {}
for line in io.lines("data/dd.csv") do
        local id, start, finish, dow, int, domain = line:match("(+%d+),(%d*:*),(%d*:*),(%d*),(%d*),(%a*.*)")
        mylist[#mylist + 1] = { id = id, start = start, finish = finish, dow = dow, int = int, domain = domain}
        print(mylist[#mylist]['id'])
end

The problem is that when the code hits a line that has empty values for start and finish, the regex fails and all fields are nil.

I thought using the * meant 0 or more... I can't seem to find my error / typo.

Thanks.

Answer 1

This pattern works for me:

"(.-),(.-),(.-),(.-),(.-),(.-)$"

Answer 2

It seems that you just need to group the digits and : inside a [...]:

match("(%+%d+),([%d:]*),([%d:]*),(%d*),(%d*),(.*)")
        ^       ^^^^^^   ^^^^^^     

Now, the [%d:]* matches zero or more digits or : symbols. Your pattern did not find the match because %d*:* matched 0+ digits followed with 0+ : symbols, and you had more than 1 such sequence.

Also, you need to escape the first + to make sure it matches a literal +.

See online Lua demo