How to check if table index exist

[Aidar Kamalov <aidar.kamalov@...>]

Hello,

I have a table generated by luasoap.

function trackNum(tracknum)
    local ns, meth, ent = client.call {
        url = "" href="http://mysite/api/service.asmx">http://mysite/api/service.asmx",
        soapaction = "http://mysite.org/Track",
        method = "Track",
        namespace = "http://mysite.org/",
        entries = {
            {
                tag = "TrackNo", tracknum,
            },
        }
    }
    local Code = ent[1][1][1][1] or "201"
    local Status = if ent[1][1][3][1][17][1] or "Unknown"
    return Code, Status
end

so, I don't know how many indexes will be in answer (btw, is it possible to address by names? for example ent['Code']) and I want to escape  error attempt to index a nil value (field '?').

What the best way to do it? something like try/except int python?

--

Aydar A. Kamalov