Cheap many to many
There are two common ways to establish a many-to-many relationship:
- 1.
has_and_belongs_to_many - 2.
has_many, :through
Both require a join table, and the second requires a little more setup than the first bit is more future-proof.
A third alternative is so simple it sounds dumb: simply add a JSON column to the parent that contains an array of child IDs. If you understand the constraints of this approach and your use case doesn't need them, it can be a flexible and noncommittal way to model relationships.
Downsides
- No guarantee of data integrity (can have orphaned IDs, no
dependent: destroy, etc.). - Cannot access list of parents from child (can't see who a model belongs to).
- Worse performance (or, at least, unmanaged performance).
Advantages
- Very noncommittal. When working with uncertainty, it's good to be as flexible as possible until you are sure of requirements. Creating a table is very committal.
- Automatic transactions. Simply update the parent record without needing to worry about data inconsistency.
- Can easily migrate to a true join-table based relationship.
Last modified 7mo ago
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