Fuzzy search issuable title or description

app/models/concerns/issuable.rb

@@ -6,6 +6,7 @@
 #
 module Issuable
   extend ActiveSupport::Concern
+  include Gitlab::SQL::Pattern
   include CacheMarkdownField
   include Participable
   include Mentionable
@@ -122,7 +123,9 @@ module Issuable
     #
     # Returns an ActiveRecord::Relation.
     def search(query)
-      where(arel_table[:title].matches("%#{query}%"))
+      title = to_fuzzy_arel(:title, query)
+
+      where(title)
     end
 
     # Searches for records with a matching title or description.
@@ -133,10 +136,10 @@ module Issuable
     #
     # Returns an ActiveRecord::Relation.
     def full_search(query)
-      t = arel_table
-      pattern = "%#{query}%"
+      title = to_fuzzy_arel(:title, query)
+      description = to_fuzzy_arel(:description, query)
 
-      where(t[:title].matches(pattern).or(t[:description].matches(pattern)))
+      where(title&.or(description))
     end
 
     def sort(method, excluded_labels: [])

lib/gitlab/sql/pattern.rb

@@ -4,6 +4,7 @@ module Gitlab
       extend ActiveSupport::Concern
 
       MIN_CHARS_FOR_PARTIAL_MATCHING = 3
+      REGEX_QUOTED_WORD = /(?<=^| )"[^"]+"(?= |$)/
 
       class_methods do
         def to_pattern(query)
@@ -17,6 +18,28 @@ module Gitlab
         def partial_matching?(query)
           query.length >= MIN_CHARS_FOR_PARTIAL_MATCHING
         end
+
+        def to_fuzzy_arel(column, query)
+          words = select_fuzzy_words(query)
+
+          matches = words.map { |word| arel_table[column].matches(to_pattern(word)) }
+
+          matches.reduce { |result, match| result.and(match) }
+        end
+
+        def select_fuzzy_words(query)
+          quoted_words = query.scan(REGEX_QUOTED_WORD)
+
+          query = quoted_words.reduce(query) { |q, quoted_word| q.sub(quoted_word, '') }
+
+          words = query.split(/\s+/)
+
+          quoted_words.map! { |quoted_word| quoted_word[1..-2] }
+
+          words.concat(quoted_words)
+
+          words.select { |word| partial_matching?(word) }
+        end
       end
     end
   end

spec/lib/gitlab/sql/pattern_spec.rb

@@ -52,4 +52,124 @@ describe Gitlab::SQL::Pattern do
       end
     end
   end
+
+  describe '.select_fuzzy_words' do
+    subject(:select_fuzzy_words) { Issue.select_fuzzy_words(query) }
+
+    context 'with a word equal to 3 chars' do
+      let(:query) { 'foo' }
+
+      it 'returns array cotaining a word' do
+        expect(select_fuzzy_words).to match_array(['foo'])
+      end
+    end
+
+    context 'with a word shorter than 3 chars' do
+      let(:query) { 'fo' }
+
+      it 'returns empty array' do
+        expect(select_fuzzy_words).to match_array([])
+      end
+    end
+
+    context 'with two words both equal to 3 chars' do
+      let(:query) { 'foo baz' }
+
+      it 'returns array containing two words' do
+        expect(select_fuzzy_words).to match_array(%w[foo baz])
+      end
+    end
+
+    context 'with two words divided by two speces both equal to 3 chars' do
+      let(:query) { 'foo  baz' }
+
+      it 'returns array containing two words' do
+        expect(select_fuzzy_words).to match_array(%w[foo baz])
+      end
+    end
+
+    context 'with two words equal to 3 chars and shorter than 3 chars' do
+      let(:query) { 'foo ba' }
+
+      it 'returns array containing a word' do
+        expect(select_fuzzy_words).to match_array(['foo'])
+      end
+    end
+
+    context 'with a multi-word surrounded by double quote' do
+      let(:query) { '"really bar"' }
+
+      it 'returns array containing a multi-word' do
+        expect(select_fuzzy_words).to match_array(['really bar'])
+      end
+    end
+
+    context 'with a multi-word surrounded by double quote and two words' do
+      let(:query) { 'foo "really bar" baz' }
+
+      it 'returns array containing a multi-word and tow words' do
+        expect(select_fuzzy_words).to match_array(['foo', 'really bar', 'baz'])
+      end
+    end
+
+    context 'with a multi-word surrounded by double quote missing a spece before the first double quote' do
+      let(:query) { 'foo"really bar"' }
+
+      it 'returns array containing two words with double quote' do
+        expect(select_fuzzy_words).to match_array(['foo"really', 'bar"'])
+      end
+    end
+
+    context 'with a multi-word surrounded by double quote missing a spece after the second double quote' do
+      let(:query) { '"really bar"baz' }
+
+      it 'returns array containing two words with double quote' do
+        expect(select_fuzzy_words).to match_array(['"really', 'bar"baz'])
+      end
+    end
+
+    context 'with two multi-word surrounded by double quote and two words' do
+      let(:query) { 'foo "really bar" baz "awesome feature"' }
+
+      it 'returns array containing two multi-words and tow words' do
+        expect(select_fuzzy_words).to match_array(['foo', 'really bar', 'baz', 'awesome feature'])
+      end
+    end
+  end
+
+  describe '.to_fuzzy_arel' do
+    subject(:to_fuzzy_arel) { Issue.to_fuzzy_arel(:title, query) }
+
+    context 'with a word equal to 3 chars' do
+      let(:query) { 'foo' }
+
+      it 'returns a single ILIKE condition' do
+        expect(to_fuzzy_arel.to_sql).to eq(%("issues"."title" ILIKE '%foo%'))
+      end
+    end
+
+    context 'with a word shorter than 3 chars' do
+      let(:query) { 'fo' }
+
+      it 'returns nil' do
+        expect(to_fuzzy_arel).to be_nil
+      end
+    end
+
+    context 'with two words both equal to 3 chars' do
+      let(:query) { 'foo baz' }
+
+      it 'returns a joining ILIKE condition using a AND' do
+        expect(to_fuzzy_arel.to_sql).to eq(%("issues"."title" ILIKE '%foo%' AND "issues"."title" ILIKE '%baz%'))
+      end
+    end
+
+    context 'with a multi-word surrounded by double quote and two words' do
+      let(:query) { 'foo "really bar" baz' }
+
+      it 'returns a joining ILIKE condition using a AND' do
+        expect(to_fuzzy_arel.to_sql).to eq(%("issues"."title" ILIKE '%foo%' AND "issues"."title" ILIKE '%baz%' AND "issues"."title" ILIKE '%really bar%'))
+      end
+    end
+  end
 end

spec/models/concerns/issuable_spec.rb

@@ -66,56 +66,76 @@ describe Issuable do
   end
 
   describe ".search" do
-    let!(:searchable_issue) { create(:issue, title: "Searchable issue") }
+    let!(:searchable_issue) { create(:issue, title: "Searchable awesome issue") }
 
-    it 'returns notes with a matching title' do
+    it 'returns issues with a matching title' do
       expect(issuable_class.search(searchable_issue.title))
         .to eq([searchable_issue])
     end
 
-    it 'returns notes with a partially matching title' do
+    it 'returns issues with a partially matching title' do
       expect(issuable_class.search('able')).to eq([searchable_issue])
     end
 
-    it 'returns notes with a matching title regardless of the casing' do
+    it 'returns issues with a matching title regardless of the casing' do
       expect(issuable_class.search(searchable_issue.title.upcase))
         .to eq([searchable_issue])
     end
+
+    it 'returns issues with a fuzzy matching title' do
+      expect(issuable_class.search('searchable issue')).to eq([searchable_issue])
+    end
+
+    it 'returns all issues with a query shorter than 3 chars' do
+      expect(issuable_class.search('zz')).to eq(issuable_class.all)
+    end
   end
 
   describe ".full_search" do
     let!(:searchable_issue) do
-      create(:issue, title: "Searchable issue", description: 'kittens')
+      create(:issue, title: "Searchable awesome issue", description: 'Many cute kittens')
     end
 
-    it 'returns notes with a matching title' do
+    it 'returns issues with a matching title' do
       expect(issuable_class.full_search(searchable_issue.title))
         .to eq([searchable_issue])
     end
 
-    it 'returns notes with a partially matching title' do
+    it 'returns issues with a partially matching title' do
       expect(issuable_class.full_search('able')).to eq([searchable_issue])
     end
 
-    it 'returns notes with a matching title regardless of the casing' do
+    it 'returns issues with a matching title regardless of the casing' do
       expect(issuable_class.full_search(searchable_issue.title.upcase))
         .to eq([searchable_issue])
     end
 
-    it 'returns notes with a matching description' do
+    it 'returns issues with a fuzzy matching title' do
+      expect(issuable_class.full_search('searchable issue')).to eq([searchable_issue])
+    end
+
+    it 'returns issues with a matching description' do
       expect(issuable_class.full_search(searchable_issue.description))
         .to eq([searchable_issue])
     end
 
-    it 'returns notes with a partially matching description' do
+    it 'returns issues with a partially matching description' do
       expect(issuable_class.full_search(searchable_issue.description))
         .to eq([searchable_issue])
     end
 
-    it 'returns notes with a matching description regardless of the casing' do
+    it 'returns issues with a matching description regardless of the casing' do
       expect(issuable_class.full_search(searchable_issue.description.upcase))
         .to eq([searchable_issue])
     end
+
+    it 'returns issues with a fuzzy matching description' do
+      expect(issuable_class.full_search('many kittens')).to eq([searchable_issue])
+    end
+
+    it 'returns all issues with a query shorter than 3 chars' do
+      expect(issuable_class.search('zz')).to eq(issuable_class.all)
+    end
   end
 
   describe '.to_ability_name' do