FEATURE: Add search not operator for tags.

lib/search.rb

@@ -465,32 +465,16 @@ class Search
     end
   end
 
-  advanced_filter(/tags?:([a-zA-Z0-9,\-_+]+)/) do |posts, match|
+  advanced_filter(/^tags?:([a-zA-Z0-9,\-_+]+)/) do |posts, match|
-    if match.include?('+')
+    search_tags(posts, match, positive: true)
-      tags = match.split('+')
-
-      posts.where("topics.id IN (
-      SELECT tt.topic_id
-      FROM topic_tags tt, tags
-      WHERE tt.tag_id = tags.id
-      GROUP BY tt.topic_id
-      HAVING to_tsvector(#{default_ts_config}, array_to_string(array_agg(tags.name), ' ')) @@ to_tsquery(#{default_ts_config}, ?)
-      )", tags.join('&'))
-    else
-      tags = match.split(",")
-
-      posts.where("topics.id IN (
-      SELECT DISTINCT(tt.topic_id)
-      FROM topic_tags tt, tags
-      WHERE tt.tag_id = tags.id
-      AND tags.name in (?)
-      )", tags)
   end
+
+  advanced_filter(/\-tags?:([a-zA-Z0-9,\-_+]+)/) do |posts, match|
+    search_tags(posts, match, positive: false)
   end
 
   advanced_filter(/filetypes?:([a-zA-Z0-9,\-_]+)/) do |posts, match|
     file_extensions = match.split(",").map(&:downcase)
-
     posts.where("posts.id IN (
       SELECT post_id FROM topic_links
       WHERE extension IN (:file_extensions)
@@ -503,8 +487,33 @@ class Search
 
   private
 
-  def process_advanced_search!(term)
+  def search_tags(posts, match, positive:)
+    return if match.nil?
 
+    modifier = positive ? "" : "NOT"
+
+    if match.include?('+')
+      tags = match.split('+')
+
+      posts.where("topics.id #{modifier} IN (
+        SELECT tt.topic_id
+        FROM topic_tags tt, tags
+        WHERE tt.tag_id = tags.id
+        GROUP BY tt.topic_id
+        HAVING to_tsvector(#{default_ts_config}, array_to_string(array_agg(tags.name), ' ')) @@ to_tsquery(#{default_ts_config}, ?)
+      )", tags.join('&')).order("id")
+    else
+      tags = match.split(",")
+
+      posts.where("topics.id #{modifier} IN (
+        SELECT DISTINCT(tt.topic_id)
+        FROM topic_tags tt, tags
+        WHERE tt.tag_id = tags.id AND tags.name IN (?)
+      )", tags).order("id")
+    end
+  end
+
+  def process_advanced_search!(term)
     term.to_s.scan(/(([^" \t\n\x0B\f\r]+)?(("[^"]+")?))/).to_a.map do |(word, _)|
       next if word.blank?
 

spec/components/search_spec.rb

@@ -845,12 +845,17 @@ describe Search do
     context 'tags' do
       let(:tag1) { Fabricate(:tag, name: 'lunch') }
       let(:tag2) { Fabricate(:tag, name: 'eggs') }
+      let(:tag3) { Fabricate(:tag, name: 'sandwiches') }
       let(:topic1) { Fabricate(:topic, tags: [tag2, Fabricate(:tag)]) }
       let(:topic2) { Fabricate(:topic, tags: [tag2]) }
       let(:topic3) { Fabricate(:topic, tags: [tag1, tag2]) }
+      let(:topic4) { Fabricate(:topic, tags: [tag1, tag2, tag3]) }
+      let(:topic5) { Fabricate(:topic, tags: [tag2, tag3]) }
       let!(:post1) { Fabricate(:post, topic: topic1) }
       let!(:post2) { Fabricate(:post, topic: topic2) }
       let!(:post3) { Fabricate(:post, topic: topic3) }
+      let!(:post4) { Fabricate(:post, topic: topic4) }
+      let!(:post5) { Fabricate(:post, topic: topic5) }
 
       it 'can find posts with tag' do
         post4 = Fabricate(:post, topic: topic3, raw: "It probably doesn't help that they're green...")
@@ -862,12 +867,23 @@ describe Search do
       it 'can find posts with any tag from multiple tags' do
         Fabricate(:post)
 
-        expect(Search.execute('tags:eggs,lunch').posts.map(&:id).sort).to eq([post1.id, post2.id, post3.id].sort)
+        expect(Search.execute('tags:eggs,lunch').posts.map(&:id).sort).to eq([post1.id, post2.id, post3.id, post4.id, post5.id].sort)
       end
 
       it 'can find posts which contains all provided tags' do
-        expect(Search.execute('tags:lunch+eggs').posts.map(&:id)).to eq([post3.id])
+        expect(Search.execute('tags:lunch+eggs+sandwiches').posts.map(&:id)).to eq([post4.id].sort)
-        expect(Search.execute('tags:eggs+lunch').posts.map(&:id)).to eq([post3.id])
+        expect(Search.execute('tags:eggs+lunch+sandwiches').posts.map(&:id)).to eq([post4.id].sort)
+      end
+
+      it 'can find posts which contains provided tags and does not contain selected ones' do
+        expect(Search.execute('tags:eggs -tags:lunch').posts)
+          .to contain_exactly(post1, post2, post5)
+
+        expect(Search.execute('tags:eggs -tags:lunch+sandwiches').posts)
+          .to contain_exactly(post1, post2, post3, post5)
+
+        expect(Search.execute('tags:eggs -tags:lunch,sandwiches').posts)
+          .to contain_exactly(post1, post2)
       end
     end