Passing a table as argument to function in Lua - function

Question

I want to loop through different indexed tables by only passing the initial table as an argument.
I currently have this table:
local table = {
stuff_1 = {
categories = {},
[1] = {
name = 'wui',
time = 300
}
},
stuff_2 = {
categories = {'stuff_10', 'stuff_11', 'stuff_12'},
stuff_10 = {
categories = {},
[1] = {
name = 'peo',
time = 150
},
[2] = {
name = 'uik',
time = 15
},
[3] = {
name = 'kpk',
time = 1230
},
[4] = {
name = 'aer',
time = 5000
}
},
stuff_11 = {
categories = {},
[1] = {
name = 'juio',
time = 600
}
},
stuff_12 = {
categories = {},
[1] = {
name = 'erq',
time = 980
},
[2] = {
name = 'faf',
time = 8170
}
}
}
I wanted to make a recursive function to check if the name in any of those tables was equal to some certain thing and return a string.
The recursivity lies in the idea of updating this table with whatever ammount I'd like (or until a certain limit).
I don't understand exactly what's wrong since when I try:
for k, v in pairs(table) do
print(k, v, #v.categories)
end
It correctly prints:
stuff_2 table: 0x10abb0 3
stuff_1 table: 0x10aab8 0
But when passing the table as a parameter to the the function below, it gives this error:
[string "stdin"]:84: attempt to get length of field 'categories' (a nil value)
Function:
function checkMessage(table)
local i = 1
local message = ""
for k, v in pairs(table) do
if(#v.categories == 0) then
while(v[i]) do
if(v[i].name == 'opd') then
if(v[i].time ~= 0) then
message = "return_1"
else
message = "return_2"
end
end
i = i + 1
end
else
checkMessage(table[k])
end
end
return message
end
EDIT: The problem lies in not ignoring that when using pairs onto the table, this doesn't just have tables with a category subtable but it also has a table named category, if this is ignored then the problem is fixed.

Answer 1

You're recursing into subtables that don't have a categories field. Trying to access categories on them yields nil, which you then try to use the length operator on. Hence your error:
attempt to get length of field 'categories' (a nil value)
If you can't hand trace your app, put in more print statements or get a line level debugger.