Junction Object

From AgileApps Support Wiki

In a relational database, a Lookup field in a source object can point to exactly one record in a target object. That capability creates one-to-many and many-to-one relationships. (For example, many Orders point to a single Customer. That's many-to-one. Looking at it the other way around, a Customer has multiple Orders. That's one-to-many.)

But sometimes, you need a many-to-many relationship. (For example, an Order can have multiple tags, and each tag can clearly apply to multiple orders.) You accomplish that goal with a junction object:


Here, the junction object is Orders_Tags. Every record in it points to exactly one Order and one Tag. But several records that point to the same Order can each point to a different Tag. Similarly, several records that point to the same Tag can each point to a different Order. In that way, a many-to-many (N:M) relationship is established.

Create a Junction Object Manually

You can use the platform's Wizard to create a Many to Many relationship. In that case, the Junction Object is created for you, behind the scenes.

You can also create a junction object manually (a technique you'll need to know if you create relationships programmatically):

  1. Create the object that will become the junction. For example: Orders_Tags.
  2. In that object, add a Lookup to each of the target objects. For example, related_to_Orders and related_to_Tags
  3. Customize one of the target objects. For example: Orders.
  4. Go to Object Relationships.
  5. Edit the Orders_Tags relationship.
  6. Select the Junction radio button to make the relationship many-to-many.
  7. Specify the object at the other end of the Junction, and the field to use (related_to_Tags).

The process of creating a relationship identifies Orders_Tags as a "junction" object. Because the platform knows it is a junction object, it displays records from the end-point object (Tags) when the user does a look up. (Otherwise, the user would see records from Orders_Tags.)

Record Filtering in a Junction Object Lookup

  1. Under Record Filtering, make selections for the Sort by field and the Sort Order.
  2. Under Record Filtering section, filters can be configured in Filtering Criteria.



  • Filtering Criteria value supports static values only. For example, 123, 1, 2, 3, Created By equals '56ca4a5cdc1d49a9ba044cb28ea7f021'.
  • Post Selection JavaScript is not supported with Junction Objects.
Junc obj record filter3.png