Documents have no notion of inheritance, so every generalization must be removed before translation. MongoDB can also be set to generate the _id values.
Resolve a generalization
Select the generalization, click Fix, then choose:
| Option | What happens | Available when |
|---|---|---|
| Collapse into parent | Child attributes and relationships move to the parent, with optional cardinality. A type attribute records which child each document belongs to. | Always |
| Collapse into children | The parent disappears and each child receives the parent’s attributes and relationships. | Total and exclusive generalizations only |
The values allowed in the type attribute depend on the generalization type. For example, a partial-exclusive generalization allows one child name or others; an overlapping one allows several.
Use MongoDB’s automatic _id
Select an entity identifier and click _id. NoER adds an _id attribute generated by MongoDB (ObjectId()) and keeps the original identifier as a regular field.
When no generalization is left, click Translate. Reset brings the model back to the end of the design stage.