Packages
ash
3.27.2
3.29.3
3.29.2
3.29.1
3.29.0
3.28.0
3.27.8
3.27.7
3.27.6
3.27.5
3.27.4
3.27.3
3.27.2
3.27.1
3.27.0
3.26.0
3.25.2
3.25.1
3.25.0
retired
3.24.7
3.24.6
3.24.5
3.24.4
3.24.3
3.24.2
3.24.1
3.24.0
3.23.1
3.23.0
3.22.2
3.22.1
3.22.0
3.21.3
3.21.2
3.21.1
3.21.0
3.20.0
3.19.3
3.19.2
3.19.1
3.19.0
3.18.0
3.17.1
3.17.0
3.16.0
3.15.0
3.14.1
3.14.0
retired
3.13.2
3.13.1
3.13.0
3.12.0
3.11.3
3.11.2
3.11.1
3.11.0
3.10.1
3.10.0
3.9.0
3.8.0
3.7.6
3.7.5
3.7.4
3.7.3
3.7.2
3.7.1
3.7.0
retired
3.6.3
retired
3.6.2
3.6.1
3.6.0
3.5.43
3.5.42
3.5.41
3.5.40
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3.5.6
3.5.5
3.5.4
3.5.3
3.5.2
3.5.1
3.5.0
3.4.74
retired
3.4.73
3.4.72
3.4.71
3.4.70
3.4.69
3.4.68
3.4.67
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3.4.63
3.4.62
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3.4.59
3.4.58
3.4.57
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3.4.55
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3.4.53
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3.4.51
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3.4.46
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3.4.44
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3.4.41
3.4.40
3.4.39
3.4.38
3.4.37
3.4.36
3.4.35
3.4.34
3.4.33
3.4.32
3.4.31
3.4.30
3.4.29
3.4.28
3.4.27
3.4.26
3.4.25
3.4.24
3.4.23
3.4.22
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3.4.20
3.4.19
3.4.18
3.4.17
3.4.16
3.4.15
3.4.14
3.4.13
3.4.12
3.4.11
3.4.10
3.4.9
3.4.8
3.4.7
3.4.6
3.4.5
3.4.4
3.4.3
3.4.2
3.4.1
3.4.0
3.3.3
3.3.2
3.3.1
3.3.0
3.2.6
3.2.5
3.2.4
3.2.3
3.2.2
3.2.1
3.2.0
3.1.8
3.1.7
3.1.6
3.1.5
3.1.4
3.1.3
3.1.2
3.1.1
3.1.0
3.0.16
3.0.15
3.0.14
3.0.13
3.0.12
3.0.11
3.0.10
3.0.9
3.0.8
3.0.7
3.0.6
3.0.5
3.0.4
3.0.3
3.0.2
3.0.1
3.0.0
3.0.0-rc.46
3.0.0-rc.45
3.0.0-rc.44
3.0.0-rc.43
3.0.0-rc.42
3.0.0-rc.41
3.0.0-rc.40
3.0.0-rc.39
3.0.0-rc.38
3.0.0-rc.37
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3.0.0-rc.35
3.0.0-rc.34
3.0.0-rc.33
3.0.0-rc.32
3.0.0-rc.31
3.0.0-rc.29
3.0.0-rc.28
3.0.0-rc.27
3.0.0-rc.26
3.0.0-rc.25
3.0.0-rc.24
3.0.0-rc.23
3.0.0-rc.22
3.0.0-rc.21
3.0.0-rc.20
3.0.0-rc.19
3.0.0-rc.18
3.0.0-rc.17
3.0.0-rc.16
3.0.0-rc.15
3.0.0-rc.14
3.0.0-rc.13
3.0.0-rc.12
3.0.0-rc.11
3.0.0-rc.10
3.0.0-rc.9
3.0.0-rc.8
3.0.0-rc.7
3.0.0-rc.6
3.0.0-rc.5
3.0.0-rc.4
3.0.0-rc.3
3.0.0-rc.1
3.0.0-rc.0
2.21.15
2.21.14
2.21.13
2.21.12
2.21.11
2.21.10
2.21.9
2.21.8
2.21.7
2.21.6
2.21.5
2.21.4
2.21.3
2.21.2
2.21.1
2.21.0
2.20.3
2.20.2
2.20.1
2.20.0
2.19.14
2.19.13
2.19.12
2.19.11
2.19.10
2.19.9
2.19.8
2.19.7
2.19.6
2.19.5
2.19.4
2.19.3
retired
2.19.2
retired
2.19.1
retired
2.19.0
retired
2.18.2
2.18.1
2.18.0
2.17.24
2.17.23
2.17.22
2.17.21
2.17.20
2.17.19
2.17.18
2.17.17
2.17.16
2.17.15
2.17.14
2.17.13
2.17.12
2.17.11
2.17.10
2.17.9
2.17.8
2.17.7
2.17.6
2.17.5
2.17.4
2.17.3
2.17.2
2.17.1
2.17.0
2.16.1
2.16.0
2.15.20
2.15.19
2.15.18
2.15.17
2.15.16
2.15.15
2.15.14
2.15.13
2.15.12
2.15.11
2.15.10
2.15.9
2.15.8
2.15.7
2.15.6
2.15.5
2.15.4
2.15.2
2.15.1
2.15.0
2.14.21
2.14.20
2.14.19
2.14.18
2.14.17
2.14.16
2.14.15
2.14.14
2.14.13
2.14.12
2.14.11
2.14.10
2.14.9
2.14.8
2.14.7
2.14.6
2.14.5
2.14.4
2.14.3
2.14.2
2.14.1
2.14.0
2.13.4
retired
2.13.3
2.13.2
2.13.1
2.13.0
2.12.1
2.12.0
2.11.11
2.11.10
2.11.9
2.11.8
2.11.7
2.11.6
2.11.5
2.11.4
2.11.3
2.11.2
2.11.1
2.11.0
2.11.0-rc.3
2.11.0-rc.2
2.11.0-rc.1
2.11.0-rc.0
2.10.2
2.10.1
2.10.0
2.9.29
2.9.28
2.9.27
2.9.26
2.9.25
2.9.24
2.9.23
2.9.22
2.9.21
2.9.20
2.9.19
2.9.18
2.9.17
2.9.16
2.9.15
2.9.14
2.9.13
2.9.12
2.9.11
2.9.10
2.9.9
2.9.8
2.9.7
2.9.6
2.9.5
2.9.4
2.9.3
2.9.2
2.9.1
2.9.0
2.8.1
2.8.0
2.7.1
2.7.0
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
2.6.11
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
2.5.16
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
2.5.0-rc.6
2.5.0-rc.5
2.5.0-rc.4
2.5.0-rc.3
2.5.0-rc.2
2.5.0-rc.1
2.5.0-rc.0
2.4.30
2.4.29
2.4.28
2.4.27
2.4.26
2.4.25
2.4.24
2.4.23
2.4.22
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
2.3.0
2.2.0
2.1.0
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
2.0.0-pre.8
2.0.0-pre.7
2.0.0-pre.6
2.0.0-pre.5
2.0.0-pre.4
2.0.0-pre.3
2.0.0-pre.2
2.0.0-pre.1
2.0.0-pre.0
1.53.3
1.53.2
1.53.0
1.52.0-rc.22
1.52.0-rc.21
1.52.0-rc.20
1.52.0-rc.19
1.52.0-rc.18
1.52.0-rc.17
1.52.0-rc.16
1.52.0-rc.15
1.52.0-rc.14
1.52.0-rc.13
1.52.0-rc.12
1.52.0-rc.11
1.52.0-rc.10
1.52.0-rc.9
1.52.0-rc.8
1.52.0-rc.7
1.52.0-rc.6
1.52.0-rc.5
1.52.0-rc.4
1.52.0-rc.3
1.52.0-rc.2
1.52.0-rc.1
1.52.0-rc.0
1.51.2
1.51.1
retired
1.51.0
1.50.21
1.50.20
1.50.19
1.50.18
1.50.17
1.50.16
1.50.15
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1.50.10
1.50.9
1.50.8
1.50.7
1.50.6
1.50.5
1.50.4
1.50.3
1.50.2
1.50.1
1.50.0
1.49.0
1.48.0-rc.30
1.48.0-rc.29
1.48.0-rc.28
1.48.0-rc.27
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1.48.0-rc.25
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1.48.0-rc.22
1.48.0-rc.21
1.48.0-rc.20
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1.48.0-rc.18
1.48.0-rc.17
1.48.0-rc.16
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1.48.0-rc.13
1.48.0-rc.12
1.48.0-rc.11
1.48.0-rc.10
1.48.0-rc.9
1.48.0-rc.8
1.48.0-rc.7
1.48.0-rc.6
1.48.0-rc.5
1.48.0-rc.4
1.48.0-rc.3
1.48.0-rc.2
1.48.0-rc.1
1.48.0-rc.0
1.47.12
1.47.11
1.47.10
1.47.9
1.47.8
1.47.7
1.47.6
1.47.5
1.47.4
1.47.3
1.47.2
1.47.1
1.47.0
1.46.13
1.46.12
1.46.11
1.46.10
1.46.9
1.46.8
1.46.7
1.46.6
1.46.5
1.46.4
1.46.3
1.46.2
1.46.1
1.46.0
1.45.0-rc9
1.45.0-rc8
1.45.0-rc7
1.45.0-rc6
1.45.0-rc5
1.45.0-rc4
1.45.0-rc3
1.45.0-rc20
1.45.0-rc2
1.45.0-rc19
1.45.0-rc18
1.45.0-rc17
1.45.0-rc16
1.45.0-rc15
1.45.0-rc14
1.45.0-rc13
1.45.0-rc12
1.45.0-rc11
1.45.0-rc10
1.45.0-rc1
1.45.0-rc0
1.44.13
1.44.12
1.44.11
1.44.10
1.44.9
1.44.8
1.44.7
1.44.6
1.44.5
1.44.4
1.44.3
1.44.2
1.44.1
1.44.0
1.43.12
1.43.11
1.43.10
1.43.9
1.43.8
1.43.7
1.43.6
1.43.5
1.43.4
1.43.3
1.43.2
1.43.1
1.43.0
1.42.0
1.41.12
1.41.11
1.41.10
1.41.9
1.41.8
1.41.7
1.41.6
1.41.5
1.41.4
1.41.3
1.41.2
1.41.1
1.41.0
1.40.0
1.39.7
1.39.6
1.39.5
1.39.4
1.39.3
1.39.2
1.39.1
1.39.0
1.38.0
1.37.2
1.37.1
1.37.0
1.36.22
1.36.21
1.36.19
1.36.18
1.36.17
1.36.16
1.36.15
1.36.14
1.36.13
1.36.12
1.36.11
1.36.10
1.36.9
1.36.8
1.36.7
1.36.6
1.36.5
1.36.4
1.36.3
1.36.2
1.36.0
1.35.1
1.35.0
1.34.9
1.34.8
1.34.7
1.34.6
1.34.5
1.34.4
1.34.3
1.34.2
1.34.1
1.34.0
1.33.0
1.32.2
1.32.1
1.32.0
1.31.1
1.31.0
1.30.2
1.30.1
1.29.0-rc1
1.29.0-rc0
1.28.1
1.28.0
1.27.1
1.27.0
1.26.13
1.26.12
1.26.11
1.26.10
1.26.9
1.26.8
1.26.7
1.26.6
1.26.5
1.26.4
1.26.2
1.26.1
1.26.0
1.25.8
1.25.7
1.25.6
1.25.5
1.25.4
1.25.3
1.25.2
1.25.1
1.25.0
1.24.2
1.24.1
1.24.0
1.23.3
1.23.2
1.23.1
1.23.0
1.22.1
1.22.0
1.20.1
1.20.0
1.19.1
1.19.0
1.18.1
1.18.0
1.17.1
1.17.0
1.16.2
1.15.1
1.15.0
1.14.0
1.13.4
1.13.3
1.13.2
1.13.1
1.13.0
1.12.0
1.11.1
1.11.0
1.10.0
1.9.0
1.8.0
1.7.0
1.6.8
1.6.7
1.6.6
1.6.5
1.6.4
1.6.3
1.6.2
1.6.1
1.6.0
1.5.1
1.5.0
1.4.1
1.4.0
1.3.1
1.3.0
1.2.1
1.2.0
1.1.3
1.1.2
1.1.0
1.0.3
1.0.2
1.0.1
1.0.0
0.13.1
0.13.0
0.12.0
0.10.0
0.9.1
0.9.0
0.8.0
0.7.0
0.6.5
0.6.4
0.6.3
0.6.2
0.6.1
0.6.0
0.5.2
0.5.1
0.5.0
0.4.0
0.3.0
0.2.0
0.1.9
0.1.8
0.1.3
0.1.1
0.1.0
A declarative, extensible framework for building Elixir applications.
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usage-rules/relationships.md
<!--
SPDX-FileCopyrightText: 2019 ash contributors <https://github.com/ash-project/ash/graphs/contributors>
SPDX-License-Identifier: MIT
-->
# Relationships
Relationships describe connections between resources and are a core component of Ash. Define relationships in the `relationships` block of a resource.
## Best Practices for Relationships
- Be descriptive with relationship names (e.g., use `:authored_posts` instead of just `:posts`)
- Configure foreign key constraints in your data layer if they have them (see `references` in AshPostgres)
- Always choose the appropriate relationship type based on your domain model
### Relationship Types
- For Polymorphic relationships, you can model them using `Ash.Type.Union`; see the “Polymorphic Relationships” guide for more information.
```elixir
relationships do
# belongs_to - adds foreign key to source resource
belongs_to :owner, MyApp.User do
allow_nil? false
attribute_type :integer # defaults to :uuid
end
# has_one - foreign key on destination resource
has_one :profile, MyApp.Profile
# has_many - foreign key on destination resource, returns list
has_many :posts, MyApp.Post do
filter expr(published == true)
sort published_at: :desc
end
# many_to_many - requires join resource
many_to_many :tags, MyApp.Tag do
through MyApp.PostTag
source_attribute_on_join_resource :post_id
destination_attribute_on_join_resource :tag_id
end
end
```
The join resource must be defined separately:
```elixir
defmodule MyApp.PostTag do
use Ash.Resource,
data_layer: AshPostgres.DataLayer
attributes do
uuid_primary_key :id
# Add additional attributes if you need metadata on the relationship
attribute :added_at, :utc_datetime_usec do
default &DateTime.utc_now/0
end
end
relationships do
belongs_to :post, MyApp.Post, primary_key?: true, allow_nil?: false
belongs_to :tag, MyApp.Tag, primary_key?: true, allow_nil?: false
end
actions do
defaults [:read, :destroy, create: :*, update: :*]
end
end
```
## Loading Relationships
```elixir
# Using code interface options (preferred)
post = MyDomain.get_post!(id, load: [:author, comments: [:author]])
# Complex loading with filters
posts = MyDomain.list_posts!(
query: [load: [comments: [filter: [is_approved: true], limit: 5]]]
)
# Manual query building (for complex cases)
MyApp.Post
|> Ash.Query.load(comments: MyApp.Comment |> Ash.Query.filter(is_approved == true))
|> Ash.read!()
# Loading on existing records
Ash.load!(post, :author)
```
Prefer to use the `strict?` option when loading to only load necessary fields on related data.
```elixir
MyApp.Post
|> Ash.Query.load([comments: [:title]], strict?: true)
```
## Managing Relationships
There are two primary ways to manage relationships in Ash:
### 1. Using `change manage_relationship/2-3` in Actions
Use this when input comes from action arguments:
```elixir
actions do
update :update do
# Define argument for the related data
argument :comments, {:array, :map} do
allow_nil? false
end
argument :new_tags, {:array, :map}
# Link argument to relationship management
change manage_relationship(:comments, type: :append)
# For different argument and relationship names
change manage_relationship(:new_tags, :tags, type: :append)
end
end
```
### 2. Using `Ash.Changeset.manage_relationship/3-4` in Custom Changes
Use this when building values programmatically:
```elixir
defmodule MyApp.Changes.AssignTeamMembers do
use Ash.Resource.Change
def change(changeset, _opts, context) do
members = determine_team_members(changeset, context.actor)
Ash.Changeset.manage_relationship(
changeset,
:members,
members,
type: :append_and_remove
)
end
end
```
### Quick Reference - Management Types
- `:append` - Add new related records, ignore existing
- `:append_and_remove` - Add new related records, remove missing
- `:remove` - Remove specified related records
- `:direct_control` - Full CRUD control (create/update/destroy)
- `:create` - Only create new records
### Quick Reference - Common Options
- `on_lookup: :relate` - Look up and relate existing records
- `on_no_match: :create` - Create if no match found
- `on_match: :update` - Update existing matches
- `on_missing: :destroy` - Delete records not in input
- `value_is_key: :name` - Use field as key for simple values
For comprehensive documentation, see the [Managing Relationships](https://hexdocs.pm/ash/relationships.html#managing-relationships) section.
### Examples
Creating a post with tags:
```elixir
MyDomain.create_post!(%{
title: "New Post",
body: "Content here...",
tags: [%{name: "elixir"}, %{name: "ash"}] # Creates new tags
})
# Updating a post to replace its tags
MyDomain.update_post!(post, %{
tags: [tag1.id, tag2.id] # Replaces tags with existing ones by ID
})
```