Topic outline

• Working with Reference Properties in InterSystems IRIS

  Working with Reference Properties in InterSystems IRIS

  Content Type
  Video

  Duration
  5m

  Level
  Introductory

  Learn how to model and navigate object relationships using reference properties in InterSystems IRIS® data platform. See how reference properties connect objects in InterSystems ObjectScript and Python, and how those relationships appear and can be queried using SQL. Learn how to design clearer object models that map cleanly to relational queries. ​
• Code Used in This Video

  Code Used in This Video

  Reference	Timestamp	Code
  Referenced class definition	1:09	Begin code: Class Hospital.Doctor Extends %Persistent { Property Name As %String(MAXLEN = 100); } Class Hospital.Patient Extends %Persistent { Property Name As %String(MAXLEN = 100); Property DateOfBirth As %Date; Property PrimaryCarePhysician As Hospital.Doctor; } End code.
  Assigning a reference property	1:27	Begin code: // Create and save a Doctor Set doctor = ##class(Hospital.Doctor).%New() Set doctor.Name = "Dr. Patel" Set sc = doctor.%Save() // Create a Patient Set patient = ##class(Hospital.Patient).%New() Set patient.Name = "John Smith" // Set the reference property Set patient.PrimaryCarePhysician = doctor End code.
  Navigating a reference property	1:46	Begin code: Set patient = ##class(Hospital.Patient).%OpenId(100) Write patient.PrimaryCarePhysician.Name End code.
  Chained object navigation	2:35	Write patient.PrimaryCarePhysician.Department.Name
  Viewing reference IDs in SQL	2:49	Begin code: SELECT ID, Name, PrimaryCarePhysician FROM Hospital.Patient End code.
  SQL implicit join using arrow syntax	3:08	Begin code: SELECT ID, Name, PrimaryCarePhysician->Name AS PCPName FROM Hospital.Patient End code.
  SQL explicit left join	3:41	Begin code: SELECT p.Name, d.Name AS PCPName FROM Hospital.Patient p LEFT JOIN Hospital.Doctor d ON p.PrimaryCarePhysician = d.ID End code.
  Chained implicit joins in SQL	3:53	Begin code: SELECT Name, PrimaryCarePhysician->Name AS Doctor, Department->Phone AS DepartmentPhone FROM Hospital.Patient End code.
• What's Next?

  What's Next?
  • See how reference properties connect objects across classes (documentation).
  • Learn how objects are loaded automatically when accessed (documentation).
  • Read more about traversing object relationships in SQL using implicit joins (documentation).
  • See how serial objects differ from reference properties when modeling related data (video, 5 min).