Method: Escape.html_form

Defined in:
lib/escape.rb

.html_form(pairs, sep = '&') ⇒ Object

Escape.html_form composes HTML form key-value pairs as a x-www-form-urlencoded encoded string.

Escape.html_form takes an array of pair of strings or an hash from string to string.

Escape.html_form([["a","b"], ["c","d"]]) #=> "a=b&c=d"
Escape.html_form({"a"=>"b", "c"=>"d"}) #=> "a=b&c=d"

In the array form, it is possible to use same key more than once. (It is required for a HTML form which contains checkboxes and select element with multiple attribute.)

Escape.html_form([["k","1"], ["k","2"]]) #=> "k=1&k=2"

If the strings contains characters which must be escaped in x-www-form-urlencoded, they are escaped using %-encoding.

Escape.html_form([["k=","&;="]]) #=> "k%3D=%26%3B%3D"

The separator can be specified by the optional second argument.

Escape.html_form([["a","b"], ["c","d"]], ";") #=> "a=b;c=d"

See HTML 4.01 for details.



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# File 'lib/escape.rb', line 164

def html_form(pairs, sep='&')
  r = ''
  first = true
  pairs.each {|k, v|
    # query-chars - pct-encoded - x-www-form-urlencoded-delimiters =
    #   unreserved / "!" / "$" / "'" / "(" / ")" / "*" / "," / ":" / "@" / "/" / "?"
    # query-char - pct-encoded = unreserved / sub-delims / ":" / "@" / "/" / "?"
    # query-char = pchar / "/" / "?" = unreserved / pct-encoded / sub-delims / ":" / "@" / "/" / "?"
    # unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
    # sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
    # x-www-form-urlencoded-delimiters = "&" / "+" / ";" / "="
    r << sep if !first
    first = false
    k.each_byte {|byte|
      ch = byte.chr
      if %r{[^0-9A-Za-z\-\._~:/?@!\$'()*,]}n =~ ch
        r << "%" << ch.unpack("H2")[0].upcase
      else
        r << ch
      end
    }
    r << '='
    v.each_byte {|byte|
      ch = byte.chr
      if %r{[^0-9A-Za-z\-\._~:/?@!\$'()*,]}n =~ ch
        r << "%" << ch.unpack("H2")[0].upcase
      else
        r << ch
      end
    }
  }
  r
end