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05 · Junction objects in practice

Many-to-many done properly: two master-details, sharing inherited from both sides, and a real example built end to end.

Article 15m 1 min read Updated 26 Apr 2025
05 · Junction objects in practice
Modules
Apex Triggers
  1. Module overview
  2. 01 · Order of execution, the map
  3. 02 · One trigger per object
  4. 03 · The handler pattern
  5. 04 · Bulkification: 200 records or bust
  6. 05 · Recursion control
Data Model Basics
  1. Module overview
  2. 01 · Standard objects vs custom objects
  3. 02 · Relationship types, decided with three questions
  4. 03 · Record types and when not to use them
  5. 04 · Schema Builder, the honest map
  6. 05 · Junction objects in practice
Integration Patterns
  1. Module overview
  2. 01 · Request-reply with named credentials
  3. 02 · Fire-and-forget with platform events
  4. 03 · Batch sync without tears
  5. 04 · Middleware or point-to-point?
  6. 05 · Watch: a callout built end to end

Many-to-many done properly: two master-details, sharing inherited from both sides, and a real example built end to end.

The pattern

A Course can have many Students, a Student many Courses: the Enrollment junction object carries two master-detail relationships and any fields that belong to the pair — grade, date, status.

Sharing rides the master-details

A junction record is visible only to users who can see BOTH parents. That is usually what you want, and it is also the first place to look when someone cannot see an enrollment.

Practice in your org

  • Open your Developer Edition org and follow along step by step
  • Change one thing at a time and note what happens
  • When something breaks, read the error before searching for it