feat(datasource-active-record): expose has_one :through as a to-one relation#327
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…elation (#325) * feat(datasource-active-record): expose has_one :through as a to-one relation Map a `has_one :through` association to a OneToOne (HasOne) schema instead of ManyToMany, so it renders as a to-one relation (matching forest_liana v1) rather than a to-many list. ActiveRecord resolves the join natively via the association name, so read, filter and aggregate all work through the relation. Resolve it efficiently too: when every hop of the through chain is a belongs_to (no scope/default_scope, same database), fold it into the existing to-one LEFT JOIN instead of issuing per-hop preload queries. When it does fall back to preload (e.g. the same relation is also used by a filter), the intermediate foreign key is now selected so ActiveRecord can still load it. * fix(datasource-active-record): address review feedback on has_one :through to-one - select the intermediate through FK only when it lives on the root table (the through hop is a belongs_to); a has_one through hop keeps the FK on the child, so selecting it against the root table emitted an invalid column. - count the intermediate through table in the JOIN safeguard so a separately projected relation on that same table falls back to preload instead of being JOINed twice (which ActiveRecord would alias, breaking column references). - document that a has_one :through to-one is display-only: it has no direct foreign key, so updating/associating it via the OneToOne write path is unsupported (the link lives on the intermediate table). - simplify belongs_to_chain_through?. * docs(datasource-active-record): drop comments added for has_one :through work * test(datasource-active-record): guard single JOIN for filter-joined has_one :through --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
4 new issues
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![qltysh[bot]](https://avatars.githubusercontent.com/in/890766?s=60&v=4){kind=small}
| origin_key: association.klass.primary_key, | ||
| origin_key_target: @model.primary_key | ||
| ) | ||
| ) |
| origin_type_value: is_polymorphic ? @model.name : nil, | ||
| foreign_type_field: source_polymorphic ? association.source_reflection.foreign_type : nil, | ||
| foreign_type_value: source_polymorphic ? association.options[:source_type] : nil | ||
| ) |
| return if used_tables.include?(target.model.table_name) # a table joined twice would be aliased by AR | ||
| return if through_tables(collection, relation_name).intersect?(used_tables) | ||
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| target |
| through = reflection.through_reflection | ||
| source = reflection.source_reflection | ||
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| through && source && through.belongs_to? && source.belongs_to? && |
![macroscopeapp[bot]](https://avatars.githubusercontent.com/in/900172?s=60&v=4){kind=small}
…ugh key root_through_foreign_key returns an array for a composite-key belongs_to through hop; interpolating it directly produced malformed SQL. Emit one select entry per key instead. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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# [1.35.0](v1.34.2...v1.35.0) (2026-07-03) ### Features * **datasource-active-record:** expose has_one :through as a to-one relation ([#327](#327)) ([9788b60](9788b60))
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🎉 This PR is included in version 1.35.0 🎉 The release is available on GitHub release Your semantic-release bot 📦🚀 |
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Re-opens the work from #325 (has_one :through exposed as a to-one relation) with a corrected commit message: the footer is removed so semantic-release publishes this as a minor (1.35.0) rather than a major.
What it does
Maps a
has_one :throughassociation to a OneToOne (HasOne) schema instead of ManyToMany, so it renders as a to-one relation (matching forest_liana v1). ActiveRecord resolves the join natively via the association name, so read, filter and aggregate all work through the relation. When every hop of the through chain is a belongs_to (no scope, same database), it folds into the existing to-one LEFT JOIN instead of per-hop preload queries; otherwise it falls back to preload with the intermediate FK selected.Note
Expose non-polymorphic
has_one :throughassociations as OneToOne relations in ActiveRecord datasourcehas_one :throughassociations now produce aOneToOneSchemainstead ofManyToManySchemain the collection schema builder, withorigin_keyset to the target model's primary key.belongs_tohops,Utils::Querycollapses it into a single SQL query using LEFT OUTER JOINs; other chains fall back to preload.belongs_to_chain_through?,through_tables, androot_through_foreign_keyguard against unsafe JOINs and ensure intermediate foreign key columns are selected.has_one :through(non-polymorphic) relation that previously appeared as ManyToMany in Forest Admin will now appear as OneToOne, which may affect how it is queried or displayed.Macroscope summarized 0ee19cd.