Lua error while adding characters to write on file

Question

I have a ESP8266 module with nodemcu firmware that must be programmed using lua. I wrote some code to save username/password credentials that are entered from a html page in a file.

This is the lua function and it works fine

   function parse_wifi_credentials(vars)
    if vars == nil or vars == "" then
        return false
    end

  local _, _, wifi_ssid = string.find(vars, "wifi_ssid\=([^&]+)")
  local _, _, wifi_password = string.find(vars, "wifi_password\=([^&]+)")

    if wifi_ssid == nil or wifi_ssid == "" or wifi_password == nil then
        return false
    end

    pwd_len = string.len(wifi_password)
    if pwd_len ~= 0 and (pwd_len < 8 or pwd_len > 64) then
        return false
    end

   file.open("credentials.txt", "a")
   file.write(wifi_ssid)
   file.write(wifi_password)
   file.flush()
   file.close()

    return true
end

It all works but my output file is something like

usernamepasswordotherusernameotherpassword

So I inserted values to separate fields like

 file.write(wifi_ssid)
 file.write(":")
 file.write(wifi_password)

and many other ways like this but my code does not work on my ESP8266 because I get not enough memory error but if I don't print the : I have something like 10 kb free.

I also tried file.write(wifi_ssid, "\n") and it works but the output doesn't change.

Annyone knows what should I do to insert a character beetwen fields?

cagdas cagdas · Accepted Answer · 2016-11-21T16:58:07

You need to use

file.writeline(wifi_ssid)

to use end of line char at the file line.

To be sure about if file open causing out of mem problem due to its garbage content, you can delete it first and re-write the credentials.

Also it is good to have collectgarbage() method after your file.writeln or flush operations.

Lua error while adding characters to write on file

1 Answers