Add Marketo Custom Object Link Fields

Last update: August 7, 2023

When you create custom objects, you must provide link fields to connect the custom object record to the correct parent record.

  • For a one-to-many custom structure, use the link field in the custom object to connect it to a person or a company.
  • For a many-to-many structure, you use two link fields, connected from a separately created intermediary object (which is a type of custom object, too). One link connects to people or companies in your database and the other connects to the custom object. In this case, the link field is not located in the custom object itself.
IMPORTANT
Marketo Engage only supports a single edge object for each bridge object in the Many to Many relationship. In the sample given below, each enrollment can only link to a single course. However, there can be many bridge objects for each edge object, just as there are many student enrollments to each course (Many-to-One relationship). If you have your custom object data structured so that there are more than one Edge object records for each Bridge object record (One-to-Many or Many-to-Many), you can create multiple Bridge object records that each refer to a single Edge object record to represent that data in Marketo.

Here’s how to create a link field in a custom object for a one-to-many structure.

  1. Go to the Admin area.

  2. Click Marketo Custom Objects.

  3. Select the custom object in the list.

  4. In the Fields tab, click New Field.

  5. Name the link field and add an optional Description. Be sure to select the Link data type.

    CAUTION
    You won’t be able to go back and create, edit, or delete a Link or Dedupe Field once the custom object is approved.

  6. Select whether the Link Object is for a lead (person) or a company.

    NOTE
    If you choose lead, you’ll see Id, email Address, and any custom fields in the list.
    If you choose company, you’ll see Id and any custom fields in the list.

  7. Select the Link Field you want to connect to as the parent of the new field.

    NOTE
    Only string field types are supported in the link field.

  8. Click Save.

Here’s how to create a link field in an intermediary object for use in a many-to-many structure.

PREREQUISITES
You must have already created the intermediary object and any custom objects you intend to link it to.

  1. Go to the Admin area.

  2. Click Marketo Custom Objects.

  3. Select the intermediary object you want to add the field to.

  4. In the Fields tab, click New Field.

  5. You need to create two link fields. Create them one at a time. First, name the field for the members of your database list (leadID, for example). Add an optional Description. Be sure to select the link Data Type.

    CAUTION
    You won’t be able to go back and create, edit, or delete a Link or Dedupe Field once the custom object is approved.

  6. Select the Link Object from your database; in this case, Lead.

  7. Select the Link Field you want to connect to, in this case, Id.

    NOTE
    Only string field types are supported in the Link Field.

  8. Click Save.

  9. Repeat this process for the second link to your custom object, in this example, courseID. The Link Object name will be course, and the Link Field will be courseID. Since you already created and approved the course custom object, these selections are available in the drop-down menus.

  10. Create any other fields that you want to use in your intermediary object, such as enrollmentID or grade.