ruby 42 lines · 9 steps

Building a Wi-Fi QR code payload in Ruby

A module that turns network credentials into the WIFI: string format that QR scanners understand.

Explained by highlit
Intermediate string-formatting validation escaping modules keyword-arguments
1module WifiQrCode
2 ESCAPE_CHARS = /([\\;,:"])/.freeze
3 
4 AUTH_TYPES = {
5 wpa: "WPA",
6 wpa2: "WPA",
7 wpa3: "WPA",
8 wep: "WEP",
9 none: "nopass"
10 }.freeze
11 
12 module_function
13 
14 def payload(ssid:, password: nil, auth: :wpa2, hidden: false)
15 auth_type = AUTH_TYPES.fetch(auth) do
16 raise ArgumentError, "unsupported auth type: #{auth.inspect}"
17 end
18 
19 if auth_type == "nopass"
20 password = nil
21 elsif password.to_s.empty?
22 raise ArgumentError, "password required for #{auth} networks"
23 end
24 
25 fields = {
26 "T" => auth_type,
27 "S" => escape(ssid),
28 "P" => (escape(password) unless password.nil?),
29 "H" => ("true" if hidden)
30 }
31 
32 segments = fields.filter_map do |key, value|
33 "#{key}:#{value}" unless value.nil?
34 end
35 
36 "WIFI:#{segments.join(';')};;"
37 end
38 
39 def escape(value)
40 value.to_s.gsub(ESCAPE_CHARS, '\\\\\1')
41 end
42end
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Mapping user-facing aliases to a canonical vocabulary keeps input flexible while output stays consistent.
  2. 2Escaping reserved characters before joining fields prevents delimiters in data from corrupting the format.
  3. 3Building a hash then filtering nils cleanly omits optional fields from a serialized string.

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