diacritic & case insensitive search (Rails, MySql, MongoDB).md

readme.md

Word.destroy_all
WordMongo.destroy_all

Word.create(name: 'xа́е́x')
WordMongo.create(name: 'xа́е́x')

search  = 'Xа́е́x'
pattern = /#{RegexpExtension.accent_insensitive_pattern Regexp.escape(search)}/
wm      = WordMongo.where(name: pattern).first

search  = 'Xа́е́x'
pattern = RegexpExtension.accent_insensitive_pattern(Regexp.escape(search)).to_s
w       = Word.where('name RLIKE ?', pattern).first

regexp_extension.rb

class RegexpExtension

  ACCENTED = {
    'A' => "[Aa\u00aa\u00c0-\u00c5\u00e0-\u00e5\u0100-\u0105\u01cd\u01ce\u0200-\u0203\u0226\u0227\u1d2c\u1d43\u1e00\u1e01\u1e9a\u1ea0-\u1ea3\u2090\u2100\u2101\u213b\u249c\u24b6\u24d0\u3371-\u3374\u3380-\u3384\u3388\u3389\u33a9-\u33af\u33c2\u33ca\u33df\u33ff\uff21\uff41]",
    'B' => "[Bb\u1d2e\u1d47\u1e02-\u1e07\u212c\u249d\u24b7\u24d1\u3374\u3385-\u3387\u33c3\u33c8\u33d4\u33dd\uff22\uff42]",
    'C' => "[Cc\u00c7\u00e7\u0106-\u010d\u1d9c\u2100\u2102\u2103\u2105\u2106\u212d\u216d\u217d\u249e\u24b8\u24d2\u3376\u3388\u3389\u339d\u33a0\u33a4\u33c4-\u33c7\uff23\uff43]",
    'D' => "[Dd\u010e\u010f\u01c4-\u01c6\u01f1-\u01f3\u1d30\u1d48\u1e0a-\u1e13\u2145\u2146\u216e\u217e\u249f\u24b9\u24d3\u32cf\u3372\u3377-\u3379\u3397\u33ad-\u33af\u33c5\u33c8\uff24\uff44]",
    'E' => "[Ee\u00c8-\u00cb\u00e8-\u00eb\u0112-\u011b\u0204-\u0207\u0228\u0229\u1d31\u1d49\u1e18-\u1e1b\u1eb8-\u1ebd\u2091\u2121\u212f\u2130\u2147\u24a0\u24ba\u24d4\u3250\u32cd\u32ce\uff25\uff45]",
    'F' => "[Ff\u1da0\u1e1e\u1e1f\u2109\u2131\u213b\u24a1\u24bb\u24d5\u338a-\u338c\u3399\ufb00-\ufb04\uff26\uff46]",
    'G' => "[Gg\u011c-\u0123\u01e6\u01e7\u01f4\u01f5\u1d33\u1d4d\u1e20\u1e21\u210a\u24a2\u24bc\u24d6\u32cc\u32cd\u3387\u338d-\u338f\u3393\u33ac\u33c6\u33c9\u33d2\u33ff\uff27\uff47]",
    'H' => "[Hh\u0124\u0125\u021e\u021f\u02b0\u1d34\u1e22-\u1e2b\u1e96\u210b-\u210e\u24a3\u24bd\u24d7\u32cc\u3371\u3390-\u3394\u33ca\u33cb\u33d7\uff28\uff48]",
    'I' => "[Ii\u00cc-\u00cf\u00ec-\u00ef\u0128-\u0130\u0132\u0133\u01cf\u01d0\u0208-\u020b\u1d35\u1d62\u1e2c\u1e2d\u1ec8-\u1ecb\u2071\u2110\u2111\u2139\u2148\u2160-\u2163\u2165-\u2168\u216a\u216b\u2170-\u2173\u2175-\u2178\u217a\u217b\u24a4\u24be\u24d8\u337a\u33cc\u33d5\ufb01\ufb03\uff29\uff49]",
    'J' => "[Jj\u0132-\u0135\u01c7-\u01cc\u01f0\u02b2\u1d36\u2149\u24a5\u24bf\u24d9\u2c7c\uff2a\uff4a]",
    'K' => "[Kk\u0136\u0137\u01e8\u01e9\u1d37\u1d4f\u1e30-\u1e35\u212a\u24a6\u24c0\u24da\u3384\u3385\u3389\u338f\u3391\u3398\u339e\u33a2\u33a6\u33aa\u33b8\u33be\u33c0\u33c6\u33cd-\u33cf\uff2b\uff4b]",
    'L' => "[Ll\u0139-\u0140\u01c7-\u01c9\u02e1\u1d38\u1e36\u1e37\u1e3a-\u1e3d\u2112\u2113\u2121\u216c\u217c\u24a7\u24c1\u24db\u32cf\u3388\u3389\u33d0-\u33d3\u33d5\u33d6\u33ff\ufb02\ufb04\uff2c\uff4c]",
    'M' => "[Mm\u1d39\u1d50\u1e3e-\u1e43\u2120\u2122\u2133\u216f\u217f\u24a8\u24c2\u24dc\u3377-\u3379\u3383\u3386\u338e\u3392\u3396\u3399-\u33a8\u33ab\u33b3\u33b7\u33b9\u33bd\u33bf\u33c1\u33c2\u33ce\u33d0\u33d4-\u33d6\u33d8\u33d9\u33de\u33df\uff2d\uff4d]",
    'N' => "[Nn\u00d1\u00f1\u0143-\u0149\u01ca-\u01cc\u01f8\u01f9\u1d3a\u1e44-\u1e4b\u207f\u2115\u2116\u24a9\u24c3\u24dd\u3381\u338b\u339a\u33b1\u33b5\u33bb\u33cc\u33d1\uff2e\uff4e]",
    'O' => "[Oo\u00ba\u00d2-\u00d6\u00f2-\u00f6\u014c-\u0151\u01a0\u01a1\u01d1\u01d2\u01ea\u01eb\u020c-\u020f\u022e\u022f\u1d3c\u1d52\u1ecc-\u1ecf\u2092\u2105\u2116\u2134\u24aa\u24c4\u24de\u3375\u33c7\u33d2\u33d6\uff2f\uff4f]",
    'P' => "[Pp\u1d3e\u1d56\u1e54-\u1e57\u2119\u24ab\u24c5\u24df\u3250\u3371\u3376\u3380\u338a\u33a9-\u33ac\u33b0\u33b4\u33ba\u33cb\u33d7-\u33da\uff30\uff50]",
    'Q' => "[Qq\u211a\u24ac\u24c6\u24e0\u33c3\uff31\uff51]",
    'R' => "[Rr\u0154-\u0159\u0210-\u0213\u02b3\u1d3f\u1d63\u1e58-\u1e5b\u1e5e\u1e5f\u20a8\u211b-\u211d\u24ad\u24c7\u24e1\u32cd\u3374\u33ad-\u33af\u33da\u33db\uff32\uff52]",
    'S' => "[Ss\u015a-\u0161\u017f\u0218\u0219\u02e2\u1e60-\u1e63\u20a8\u2101\u2120\u24ae\u24c8\u24e2\u33a7\u33a8\u33ae-\u33b3\u33db\u33dc\ufb06\uff33\uff53]",
    'T' => "[Tt\u0162-\u0165\u021a\u021b\u1d40\u1d57\u1e6a-\u1e71\u1e97\u2121\u2122\u24af\u24c9\u24e3\u3250\u32cf\u3394\u33cf\ufb05\ufb06\uff34\uff54]",
    'U' => "[Uu\u00d9-\u00dc\u00f9-\u00fc\u0168-\u0173\u01af\u01b0\u01d3\u01d4\u0214-\u0217\u1d41\u1d58\u1d64\u1e72-\u1e77\u1ee4-\u1ee7\u2106\u24b0\u24ca\u24e4\u3373\u337a\uff35\uff55]",
    'V' => "[Vv\u1d5b\u1d65\u1e7c-\u1e7f\u2163-\u2167\u2173-\u2177\u24b1\u24cb\u24e5\u2c7d\u32ce\u3375\u33b4-\u33b9\u33dc\u33de\uff36\uff56]",
    'W' => "[Ww\u0174\u0175\u02b7\u1d42\u1e80-\u1e89\u1e98\u24b2\u24cc\u24e6\u33ba-\u33bf\u33dd\uff37\uff57]",
    'X' => "[Xx\u02e3\u1e8a-\u1e8d\u2093\u213b\u2168-\u216b\u2178-\u217b\u24b3\u24cd\u24e7\u33d3\uff38\uff58]",
    'Y' => "[Yy\u00dd\u00fd\u00ff\u0176-\u0178\u0232\u0233\u02b8\u1e8e\u1e8f\u1e99\u1ef2-\u1ef9\u24b4\u24ce\u24e8\u33c9\uff39\uff59]",
    'Z' => "[Zz\u0179-\u017e\u01f1-\u01f3\u1dbb\u1e90-\u1e95\u2124\u2128\u24b5\u24cf\u24e9\u3390-\u3394\uff3a\uff5a]"
  } unless const_defined? :ACCENTED

  def self.accent_insensitive_pattern(search)
    search.each_char.collect { |char| ACCENTED[char.upcase] || char } .join
  end

end

word.rb

class Word < ApplicationRecord
end

word_mongo.rb

class WordMongo
  include Mongoid::Document

  field :name, type: String
end