FEATURE: Allow admins to pre-populate user fields (#12361)

Admins can use bulk invites to pre-populate user fields. The imported
CSV file must have a header with "email" column (first position) and
names of the user fields (exact match).

Under the hood, the bulk invite will create staged users and populate
the user fields of those.

spec/requests/invites_controller_spec.rb

@@ -27,6 +27,20 @@ describe InvitesController do
       expect(response.body).not_to include('i*****g@a***********e.ooo')
     end
 
+    it 'shows default user fields' do
+      user_field = Fabricate(:user_field)
+      staged_user = Fabricate(:user, staged: true, email: invite.email)
+      staged_user.set_user_field(user_field.id, 'some value')
+      staged_user.save_custom_fields
+
+      get "/invites/#{invite.invite_key}"
+      expect(response.body).to have_tag("div#data-preloaded") do |element|
+        json = JSON.parse(element.current_scope.attribute('data-preloaded').value)
+        invite_info = JSON.parse(json['invite_info'])
+        expect(invite_info['user_fields'][user_field.id.to_s]).to eq('some value')
+      end
+    end
+
     it 'fails for logged in users' do
       sign_in(Fabricate(:user))
 
@@ -691,6 +705,9 @@ describe InvitesController do
       let(:csv_file) { File.new("#{Rails.root}/spec/fixtures/csv/discourse.csv") }
       let(:file) { Rack::Test::UploadedFile.new(File.open(csv_file)) }
 
+      let(:csv_file_with_headers) { File.new("#{Rails.root}/spec/fixtures/csv/discourse_headers.csv") }
+      let(:file_with_headers) { Rack::Test::UploadedFile.new(File.open(csv_file_with_headers)) }
+
       it 'fails if you cannot bulk invite to the forum' do
         sign_in(Fabricate(:user))
         post '/invites/upload_csv.json', params: { file: file, name: 'discourse.csv' }
@@ -713,6 +730,24 @@ describe InvitesController do
         expect(Jobs::BulkInvite.jobs.size).to eq(1)
         expect(response.parsed_body['errors'][0]).to eq(I18n.t('bulk_invite.max_rows', max_bulk_invites: SiteSetting.max_bulk_invites))
       end
+
+      it 'can import user fields' do
+        Jobs.run_immediately!
+        user_field = Fabricate(:user_field, name: "location")
+        Fabricate(:group, name: 'discourse')
+        Fabricate(:group, name: 'ubuntu')
+
+        sign_in(admin)
+
+        post '/invites/upload_csv.json', params: { file: file_with_headers, name: 'discourse_headers.csv' }
+        expect(response.status).to eq(200)
+
+        user = User.where(staged: true).find_by_email('test@example.com')
+        expect(user.user_fields[user_field.id.to_s]).to eq('usa')
+
+        user2 = User.where(staged: true).find_by_email('test2@example.com')
+        expect(user2.user_fields[user_field.id.to_s]).to eq('europe')
+      end
     end
   end
 end