Module: Twitter::Validation

Defined in:
lib/validation.rb

Constant Summary collapse

MAX_LENGTH = 
140
INVALID_CHARACTERS =

Character not allowed in Tweets

[
  0xFFFE, 0xFEFF, # BOM
  0xFFFF,         # Special
  0x202A, 0x202B, 0x202C, 0x202D, 0x202E # Directional change
].map{|cp| [cp].pack('U') }.freeze

Instance Method Summary collapse

Instance Method Details

#tweet_invalid?(text) ⇒ Boolean

Check the text for any reason that it may not be valid as a Tweet. This is meant as a pre-validation before posting to api.twitter.com. There are several server-side reasons for Tweets to fail but this pre-validation will allow quicker feedback.

Returns false if this text is valid. Otherwise one of the following Symbols will be returned:

<tt>:too_long</tt>:: if the <tt>text</tt> is too long
<tt>:empty</tt>:: if the <tt>text</tt> is nil or empty
<tt>:invalid_characters</tt>:: if the <tt>text</tt> contains non-Unicode or any of the disallowed Unicode characters

Returns:

  • (Boolean) 


38
39
40
41
42
43
44
45
46
47
48
49
50
 
# File 'lib/validation.rb', line 38

def tweet_invalid?(text)
  begin
    return :empty if text.blank?
    return :too_long if tweet_length(text) > MAX_LENGTH
    return :invalid_characters if INVALID_CHARACTERS.any?{|invalid_char| text.include?(invalid_char) }
    return :invalid_characters if false
  rescue ArgumentError, ActiveSupport::Multibyte::EncodingError => e
    # non-Unicode value.
    return :invalid_characters
  end

  return false
end

#tweet_length(text) ⇒ Object

Returns the length of the string as it would be displayed. This is equivilent to the length of the Unicode NFC (See: www.unicode.org/reports/tr15). This is needed in order to consistently calculate the length of a string no matter which actual form was transmitted. For example:

U+0065  Latin Small Letter E

+ U+0301 Combining Acute Accent

2 bytes, 2 characters, displayed as é (1 visual glyph)

… The NFC of {U+0065, U+0301} is {U+00E9}, which is a single chracter and a +display_length+ of 1

The string could also contain U+00E9 already, in which case the canonicalization will not change the value.



25
26
27
 
# File 'lib/validation.rb', line 25

def tweet_length(text)
  ActiveSupport::Multibyte::Chars.new(text).normalize(:c).length
end