add readResult support to LTI grade passback, refs #5892

testplan: you can set up an assignment as an external_tool type
manually, and then hit the IMS certification test tool to verify that
replaceResult and readResult are now fully supported.

Change-Id: Id193ba1943f51b3cb4b6a2d078d8a2262c26659e
Reviewed-on: https://gerrit.instructure.com/6678
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Brian Whitmer <brian@instructure.com>

app/controllers/submissions_api_controller.rb

@@ -132,7 +132,7 @@ class SubmissionsApiController < ApplicationController
   def show
     @assignment = @context.assignments.active.find(params[:assignment_id])
     @user = get_user_considering_section(params[:id])
-    @submission = @assignment.submissions.find_or_initialize_by_user_id(@user.id) or raise ActiveRecord::RecordNotFound
+    @submission = @assignment.submission_for_student(@user)
     if authorized_action(@submission, @current_user, :read)
       includes = Array(params[:include])
       render :json => submission_json(@submission, @assignment, includes).to_json

app/models/assignment.rb

@@ -484,11 +484,15 @@ class Assignment < ActiveRecord::Base
     self.grading_type ||= "points"
   end
 
+  def score_to_grade_percent(score=0.0)
+    result = score.to_f / self.points_possible
+    result = (result * 1000.0).round / 10.0
+  end
+
   def score_to_grade(score=0.0)
     result = score.to_f
     if self.grading_type == "percent"
-      result = score.to_f / self.points_possible
+      result = score_to_grade_percent(score)
-      result = (result * 1000.0).round / 10.0
       result = "#{result}%"
     elsif self.grading_type == "pass_fail"
       result = score.to_f == self.points_possible ? "complete" : "incomplete"
@@ -789,6 +793,10 @@ class Assignment < ActiveRecord::Base
     end
   end
 
+  def submission_for_student(user)
+    self.submissions.find_or_initialize_by_user_id(user.id)
+  end
+
   def grade_student(original_student, opts={})
     raise "Student is required" unless original_student
     raise "Student must be enrolled in the course as a student to be graded" unless original_student && self.context.students.include?(original_student)

lib/basic_lti/basic_outcomes.rb

@@ -19,7 +19,6 @@ module BasicLTI::BasicOutcomes
   protected
 
   def self.handle_request(tool, course, assignment, user, xml, res)
-
     # verify the lis_result_sourcedid param, which will be a canvas-signed
     # tuple of (course, assignment, user) to ensure that only this launch of
     # the tool is attempting to modify this data.
@@ -28,8 +27,15 @@ module BasicLTI::BasicOutcomes
       return false
     end
 
-    case res.operation_ref_identifier
+    op = res.operation_ref_identifier
-    when 'replaceResult'
+    if self.respond_to?("handle_#{op}")
+      return self.send("handle_#{op}", tool, course, assignment, user, xml, res)
+    end
+
+    false
+  end
+
+  def self.handle_replaceResult(tool, course, assignment, user, xml, res)
     text_value = xml.at_css('imsx_POXBody > replaceResultRequest > resultRecord > result > resultScore > textString').try(:content)
     new_value = Float(text_value) rescue false
     if new_value && (0.0 .. 1.0).include?(new_value)
@@ -43,7 +49,22 @@ module BasicLTI::BasicOutcomes
     end
   end
 
-    false
+  def self.handle_readResult(tool, course, assignment, user, xml, res)
+    submission = assignment.submission_for_student(user)
+    if submission.graded?
+      raw_score = assignment.score_to_grade_percent(submission.score)
+      score = raw_score / 100.0
+    end
+    res.body = %{
+      <readResultResponse>
+        <result>
+          <resultScore>
+            <language>en</language>
+            <textString>#{score}</textString>
+          </resultScore>
+        </result>
+      </readResultResponse>
+    }
   end
 
   class LtiResponse

spec/apis/lti/grade_passback_spec.rb

@@ -89,6 +89,30 @@ describe LtiApiController, :type => :integration do
     }
   end
 
+  def read_result(sourceid = nil)
+    sourceid ||= BasicLTI::BasicOutcomes.result_source_id(@tool, @course, @assignment, @student)
+    body = %{
+<?xml version = "1.0" encoding = "UTF-8"?>
+<imsx_POXEnvelopeRequest xmlns = "http://www.imsglobal.org/lis/oms1p0/pox">
+  <imsx_POXHeader>
+    <imsx_POXRequestHeaderInfo>
+      <imsx_version>V1.0</imsx_version>
+      <imsx_messageIdentifier>999999123</imsx_messageIdentifier>
+    </imsx_POXRequestHeaderInfo>
+  </imsx_POXHeader>
+  <imsx_POXBody>
+    <readResultRequest>
+      <resultRecord>
+        <sourcedGUID>
+          <sourcedId>#{sourceid}</sourcedId>
+        </sourcedGUID>
+      </resultRecord>
+    </readResultRequest>
+  </imsx_POXBody>
+</imsx_POXEnvelopeRequest>
+    }
+  end
+
   def check_failure(failure_type = 'unsupported')
     response.should be_success
     response.content_type.should == 'application/xml'
@@ -115,6 +139,7 @@ describe LtiApiController, :type => :integration do
       xml.at_css('imsx_POXBody *:first').name.should == 'replaceResultResponse'
       submission = @assignment.submissions.find_by_user_id(@student.id)
       submission.should be_present
+      submission.should be_graded
       submission.score.should == 12
     end
 
@@ -145,6 +170,36 @@ describe LtiApiController, :type => :integration do
     end
   end
 
+  describe "readResult" do
+    it "should return an empty string when no grade exists" do
+      make_call('body' => read_result)
+      check_success
+
+      xml = Nokogiri::XML.parse(response.body)
+      xml.at_css('imsx_codeMajor').content.should == 'success'
+      xml.at_css('imsx_messageRefIdentifier').content.should == '999999123'
+      xml.at_css('imsx_operationRefIdentifier').content.should == 'readResult'
+      xml.at_css('imsx_POXBody *:first').name.should == 'readResultResponse'
+      xml.at_css('imsx_POXBody > readResultResponse > result > resultScore > language').content.should == 'en'
+      xml.at_css('imsx_POXBody > readResultResponse > result > resultScore > textString').content.should == ''
+    end
+
+    it "should return the score if the assignment is scored" do
+      @assignment.grade_student(@student, :grade => "40%")
+
+      make_call('body' => read_result)
+      check_success
+
+      xml = Nokogiri::XML.parse(response.body)
+      xml.at_css('imsx_codeMajor').content.should == 'success'
+      xml.at_css('imsx_messageRefIdentifier').content.should == '999999123'
+      xml.at_css('imsx_operationRefIdentifier').content.should == 'readResult'
+      xml.at_css('imsx_POXBody *:first').name.should == 'readResultResponse'
+      xml.at_css('imsx_POXBody > readResultResponse > result > resultScore > language').content.should == 'en'
+      xml.at_css('imsx_POXBody > readResultResponse > result > resultScore > textString').content.should == '0.4'
+    end
+  end
+
   it "should reject if the assignment doesn't use this tool" do
     tool = @course.context_external_tools.create!(:shared_secret => 'test_secret_2', :consumer_key => 'test_key_2', :name => 'new tool', :domain => 'example.net')
     @assignment.external_tool_tag.destroy!