Make teacher search work on word prefixes

app/models/teacher.rb

@@ -25,7 +25,12 @@ class Teacher < ApplicationRecord
             teacher_reference_number: true
 
   # Scopes
-  scope :search, ->(query_string) { where("teachers.search @@ websearch_to_tsquery('unaccented', ?)", query_string) }
+  scope :search, lambda { |query_string|
+    where(
+      "teachers.search @@ to_tsquery('unaccented', ?)",
+      FullTextSearch::Query.new(query_string).search_by_all_prefixes
+    )
+  }
 
   def to_param
     trn

lib/full_text_search/query.rb

@@ -0,0 +1,19 @@
+module FullTextSearch
+  class Query
+    def initialize(string)
+      @string = string
+    end
+
+    # splits a string and adds the suffix ':*', which allows
+    # us to search for partial words, so 'Jo' would match 'John'
+    # and 'Joey'
+    #
+    # the segments are joined with '&' so 'Jo Sm' would return
+    # 'John Smith' but not 'Joan Jones'
+    #
+    # https://www.postgresql.org/docs/current/datatype-textsearch.html#DATATYPE-TSQUERY
+    def search_by_all_prefixes
+      @string.split.map { |w| w + ":*" }.join(" & ")
+    end
+  end
+end

spec/lib/full_text_search/query_spec.rb

@@ -0,0 +1,21 @@
+describe FullTextSearch::Query do
+  subject { FullTextSearch::Query.new(string).search_by_all_prefixes }
+
+  context 'when the string has no words' do
+    let(:string) { '' }
+
+    it { is_expected.to be_empty }
+  end
+
+  context 'when the string has one word (Cletus)' do
+    let(:string) { 'Cletus' }
+
+    it { is_expected.to eql('Cletus:*') }
+  end
+
+  context 'when the string has many words (Cletus Van Damme)' do
+    let(:string) { 'Cletus Van Damme' }
+
+    it { is_expected.to eql('Cletus:* & Van:* & Damme:*') }
+  end
+end

spec/models/teacher_spec.rb

@@ -40,7 +40,7 @@
   describe 'scopes' do
     describe '#search' do
       it "searches the 'search' column using a tsquery" do
-        expect(Teacher.search('Joey').to_sql).to end_with(%{WHERE (teachers.search @@ websearch_to_tsquery('unaccented', 'Joey'))})
+        expect(Teacher.search('Joey').to_sql).to end_with(%{WHERE (teachers.search @@ to_tsquery('unaccented', 'Joey:*'))})
       end
 
       describe 'basic matching' do
@@ -53,13 +53,6 @@
           expect(results).to include(target)
           expect(results).not_to include(other)
         end
-
-        it "supports web search syntax" do
-          results = Teacher.search('Wilkerson -Reese')
-
-          expect(results).to include(target)
-          expect(results).not_to include(other)
-        end
       end
 
       describe 'matching with accents' do
@@ -77,6 +70,29 @@
           expect(results).to include(target)
         end
       end
+
+      describe 'matching a prefix' do
+        let!(:target) { FactoryBot.create(:teacher, trs_first_name: "Dewey", trs_last_name: "Wilkerson", corrected_name: nil) }
+        let!(:other) { FactoryBot.create(:teacher, trs_first_name: "Reese", trs_last_name: "Wilkerson", corrected_name: nil) }
+
+        it 'matches on the start of a word' do
+          results = Teacher.search('Dew')
+
+          expect(results).to include(target)
+        end
+
+        it 'matches on multiple starts of words' do
+          results = Teacher.search('Dew Wil')
+
+          expect(results).to include(target)
+        end
+
+        it 'only on multiple starts when all match part of the name' do
+          results = Teacher.search('Dew Wil')
+
+          expect(results).not_to include(other)
+        end
+      end
     end
   end
 end