Packages
ash_postgres
2.5.15
2.10.0
2.9.1
2.9.0
2.8.0
2.7.0
2.6.32
2.6.31
2.6.30
2.6.29
2.6.28
2.6.27
2.6.26
2.6.25
2.6.24
2.6.23
2.6.22
2.6.21
2.6.20
2.6.19
2.6.18
2.6.17
2.6.16
2.6.15
2.6.14
2.6.13
2.6.12
2.6.11
2.6.10
2.6.9
2.6.8
2.6.7
2.6.6
2.6.5
2.6.4
2.6.3
2.6.2
2.6.1
2.6.0
2.5.22
2.5.21
2.5.20
2.5.19
2.5.18
2.5.17
2.5.16
2.5.15
2.5.14
2.5.13
2.5.12
2.5.11
2.5.10
2.5.9
2.5.8
2.5.7
2.5.6
2.5.5
2.5.4
2.5.3
2.5.2
2.5.1
2.5.0
2.4.21
2.4.20
2.4.19
2.4.18
2.4.17
2.4.16
2.4.15
2.4.14
2.4.13
2.4.12
2.4.11
2.4.10
2.4.9
2.4.8
2.4.7
2.4.6
2.4.5
2.4.4
2.4.3
2.4.2
2.4.1
2.4.0
2.3.1
2.3.0
2.2.5
2.2.4
2.2.3
2.2.2
2.2.1
2.2.0
2.1.19
2.1.18
2.1.17
2.1.15
2.1.14
2.1.13
2.1.12
2.1.11
2.1.10
2.1.9
2.1.8
2.1.6
2.1.5
2.1.4
2.1.3
2.1.2
2.1.1
2.1.0
2.0.12
2.0.11
2.0.10
2.0.9
2.0.8
2.0.7
2.0.6
2.0.5
2.0.4
2.0.3
2.0.2
2.0.1
2.0.0
2.0.0-rc.15
2.0.0-rc.14
2.0.0-rc.13
2.0.0-rc.12
2.0.0-rc.11
2.0.0-rc.10
2.0.0-rc.9
2.0.0-rc.8
2.0.0-rc.7
2.0.0-rc.6
2.0.0-rc.5
2.0.0-rc.4
2.0.0-rc.3
2.0.0-rc.2
2.0.0-rc.1
2.0.0-rc.0
1.5.30
1.5.29
1.5.28
1.5.27
1.5.26
1.5.25
1.5.24
1.5.23
1.5.22
1.5.21
1.5.20
1.5.19
1.5.18
1.5.17
1.5.16
1.5.15
1.5.14
1.5.13
1.5.12
1.5.11
1.5.10
1.5.9
1.5.8
1.5.7
1.5.6
1.5.5
1.5.4
1.5.3
1.5.2
1.5.1
1.5.0
1.4.0
1.3.68
1.3.67
1.3.66
1.3.65
1.3.64
1.3.63
1.3.62
1.3.61
1.3.60
1.3.59
1.3.58
1.3.56
1.3.55
1.3.54
1.3.53
1.3.52
1.3.51
1.3.50
1.3.49
1.3.48
1.3.47
1.3.46
1.3.45
1.3.44
1.3.43
1.3.42
1.3.41
1.3.40
1.3.39
1.3.38
1.3.37
1.3.36
1.3.35
1.3.34
1.3.33
1.3.32
1.3.31
1.3.30
1.3.29
1.3.28
1.3.26
1.3.25
1.3.24
1.3.23
1.3.22
1.3.21
1.3.20
1.3.19
1.3.18
1.3.17
1.3.16
1.3.15
1.3.14
1.3.12
1.3.11
1.3.10
1.3.9
1.3.8
1.3.6
1.3.5
1.3.4
1.3.3
1.3.2
1.3.1
1.3.0
1.3.0-rc.4
1.3.0-rc.3
1.3.0-rc.2
1.3.0-rc.0
1.2.6
1.2.5
1.2.4
1.2.3
1.2.2
1.2.1
1.2.0
1.2.0-rc.1
1.2.0-rc.0
1.1.3
1.1.2
1.1.1
1.1.0
1.0.0
1.0.0-rc.9
1.0.0-rc.8
1.0.0-rc.7
1.0.0-rc.6
1.0.0-rc.5
1.0.0-rc.4
1.0.0-rc.3
1.0.0-rc.2
1.0.0-rc.1
1.0.0-rc.0
1.0.0-pre.3
1.0.0-pre.2
1.0.0-pre.1
1.0.0-pre.0
0.43.0
0.42.0-rc.7
0.42.0-rc.6
0.42.0-rc.5
0.42.0-rc.4
0.42.0-rc.3
0.42.0-rc.1
0.42.0-rc.0
0.41.7
0.41.6
0.41.5
0.41.4
0.41.3
0.41.2
0.41.1
0.41.0-rc0
retired
0.41.0-rc.9
0.41.0-rc.8
0.41.0-rc.7
0.41.0-rc.6
0.41.0-rc.5
0.41.0-rc.4
0.41.0-rc.3
0.41.0-rc.2
0.41.0-rc.1
0.41.0-rc.0
0.40.11
0.40.10
0.40.9
0.40.8
0.40.7
0.40.6
0.40.5
0.40.4
0.40.3
0.40.2
0.40.1
0.40.0-rc5
0.40.0-rc4
0.40.0-rc3
0.40.0-rc2
0.40.0-rc1
0.39.0-rc0
0.38.11
0.38.10
0.38.9
0.38.8
0.38.7
0.38.6
0.38.5
0.38.4
0.38.3
0.38.2
0.38.1
0.38.0
0.37.8
0.37.7
0.37.6
0.37.5
0.37.4
0.37.3
0.37.2
0.37.1
0.37.0
0.36.5
0.36.4
0.36.3
0.36.2
0.36.1
0.36.0
0.35.5
0.35.4
0.35.3
0.35.1
0.34.5
0.34.4
0.34.3
0.34.2
0.34.1
0.34.0
0.33.1
0.33.0
0.32.2
0.32.1
0.32.0
0.31.1
0.30.1
0.29.6
0.29.5
0.29.4
0.29.3
0.29.2
0.29.1
0.28.1
0.28.0
0.27.0
0.26.2
0.26.1
0.26.0
0.25.5
0.25.4
0.25.3
0.25.2
0.25.1
0.25.0
0.24.0
0.23.2
0.23.1
0.23.0
0.22.1
0.22.0
0.21.0
0.20.1
0.20.0
0.19.0
0.18.0
0.17.0
0.16.1
0.15.0
0.14.0
0.13.0
0.12.1
0.12.0
0.11.2
0.10.0
0.9.0
0.8.0
0.7.0
0.6.0
0.5.0
0.4.0
0.3.0
0.2.1
0.2.0
0.1.4
0.1.3
0.1.2
0.1.1
0.1.1-rc.2
0.1.1-rc.1
0.1.1-rc.0
0.1.0
The PostgreSQL data layer for Ash Framework
Current section
Files
Jump to
Current section
Files
documentation/topics/resources/references.md
# References
To configure the behavior of generated foreign keys on a resource, we use the `references` section, within the `postgres` configuration block.
For example:
```elixir
postgres do
# other PostgreSQL config here
references do
reference :post, on_delete: :delete, on_update: :update, name: "comments_to_posts_fkey"
end
end
```
All supported DSL options can be found in a [datalayer documentation](https://hexdocs.pm/ash_postgres/dsl-ashpostgres-datalayer.html#postgres-references).
> ### Actions are not used for this behavior {: .warning}
>
> No resource logic is applied with these operations! No authorization rules or validations take place, and no notifications are issued. This operation happens _directly_ in the database.
## On Delete
This option describes what to do if the referenced row is deleted.
The option is called `on_delete`, instead of `on_destroy`, because it is hooking into the database level deletion, _not_ a `destroy` action in your resource. See the warning above.
The possible values for the option are `:nothing`, `:restrict`, `:delete`, `:nilify`, `{:nilify, columns}`.
With `:nothing` or `:restrict` the deletion of the referenced row is prevented.
With `:delete` the row is deleted together with the referenced row.
With `:nilify` all columns of the foreign-key constraint are nilified.
With `{:nilify, columns}` a column list can specify which columns should be set to `nil`.
If you intend to use this option to nilify a subset of the columns, note that it cannot be used together with the `match: :full` option otherwise a mix of nil and non-nil values would fail the constraint and prevent the deletion of the referenced row.
In addition, keep into consideration that this option is only supported from Postgres v15.0 onwards.
## On Update
This option describes what to do if the referenced row is updated.
The possible values for the option are `:nothing`, `:restrict`, `:update`, `:nilify`.
With `:nothing` or `:restrict` the update of the referenced row is prevented.
With `:update` the row is updated according to the referenced row.
With `:nilify` all columns of the foreign-key constraint are nilified.
## Nothing vs Restrict
```elixir
references do
reference :post, on_delete: :nothing
# vs
reference :post, on_delete: :restrict
end
```
The difference between `:nothing` and `:restrict` is subtle and, if you are unsure, choose `:nothing` (the default behavior). `:restrict` will immediately check the foreign-key constraint and prevent the update or deletion from happening, whereas `:nothing` allows the check to be deferred until later in the transaction. This allows for things like updating or deleting the destination row and _then_ updating updating or deleting the reference (as long as you are in a transaction). The reason that `:nothing` still ultimately prevents the update or deletion is because postgres enforces foreign key referential integrity.