Class: Renalware::PdfFriendlyValidator

Inherits:
ActiveModel::EachValidator
  • Object
show all
Defined in:
app/validators/renalware/pdf_friendly_validator.rb

Overview

rubocop:disable Style/AsciiComments Prawn uses the Windows-1252 character set so that it can be compatible with the limnited fonts built into PDF viewers. This has the advantage that PDF file sizes are very small (5-6KB as opposed to 40KB+ if adding a custom TTF font to allow wider glyph support). Prawn converts the content to UTF-8 before rendering, and characters, outside of the Windows-1252 set will generally be represented as e.g. ♣. However, some characters, especially glyphs (e.g. the empty checkbox x90) will raise:

Encoding::UndefinedConversionError ("\x90" to UTF-8 in conversion from
Windows-1252 to UTF-8)

We trap these and set a (hopefully-useful) validation message, asking the user to find and remove them. Hopefully this will not happen very often, though a copy and paste from Word is the most likely. If it happens a lot and irritates users, we could attempt to replace the most common offending chars. It is important we trap these errors early, with the user present, as once the event is created, the async generation of PDFs prevents changing the content. rubocop:enable Style/AsciiComments

Constant Summary collapse

PRAWN_PDF_ENCODING = 
"Windows-1252"

Instance Method Summary collapse

Instance Method Details

#validate_each(record, attribute, value) ⇒ Object 



23
24
25
26
27
28
29
30
31
32
 
# File 'app/validators/renalware/pdf_friendly_validator.rb', line 23

def validate_each(record, attribute, value)
  value.to_s.dup.force_encoding(PRAWN_PDF_ENCODING).encode("utf-8")
rescue Encoding::UndefinedConversionError
  record.errors.add(
    attribute,
    "contains unusual characters (e.g. checkboxes, special quotes) which may "\
    "stop us from using this content in a PDF. These characters can appear if copying and "\
    "pasting from Word for example."
  )
end