Correct bad where clause when no category/user found

lib/search.rb

@@ -215,13 +215,21 @@ class Search
   end
 
   advanced_filter(/category:(.+)/) do |posts,match|
-    category_id = Category.find_by('name ilike ? OR id = ?', match, match.to_i).try(:id)
-    posts.where("topics.category_id = ?", category_id)
+    category_id = Category.where('name ilike ? OR id = ?', match, match.to_i).pluck(:id).first
+    if category_id
+      posts.where("topics.category_id = ?", category_id)
+    else
+      posts.where("1 = 0")
+    end
   end
 
   advanced_filter(/user:(.+)/) do |posts,match|
-    user_id = User.find_by('username_lower = ? OR id = ?', match.downcase, match.to_i).try(:id)
-    posts.where("posts.user_id = #{user_id}")
+    user_id = User.where('username_lower = ? OR id = ?', match.downcase, match.to_i).pluck(:id).first
+    if user_id
+      posts.where("posts.user_id = #{user_id}")
+    else
+      posts.where("1 = 0")
+    end
   end
 
   advanced_filter(/min_age:(\d+)/) do |posts,match|

spec/components/search_spec.rb

@@ -373,10 +373,10 @@ describe Search do
 
   describe 'Advanced search' do
 
-    it 'supports min_age and max_age in:first' do
+    it 'supports min_age and max_age in:first user:' do
       topic = Fabricate(:topic, created_at: 3.months.ago)
       Fabricate(:post, raw: 'hi this is a test 123 123', topic: topic)
-      Fabricate(:post, raw: 'boom boom shake the room', topic: topic)
+      _post = Fabricate(:post, raw: 'boom boom shake the room', topic: topic)
 
       expect(Search.execute('test min_age:100').posts.length).to eq(1)
       expect(Search.execute('test min_age:10').posts.length).to eq(0)
@@ -387,6 +387,8 @@ describe Search do
       expect(Search.execute('boom').posts.length).to eq(1)
       expect(Search.execute('boom in:first').posts.length).to eq(0)
 
+      expect(Search.execute('user:nobody').posts.length).to eq(0)
+      expect(Search.execute("user:#{_post.user.username}").posts.length).to eq(1)
     end
 
     it 'can search numbers correctly, and match exact phrases' do