Packages
ash
2.11.2
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
3.5.39
3.5.38
3.5.37
3.5.36
3.5.35
3.5.34
3.5.33
3.5.32
3.5.31
3.5.30
3.5.29
3.5.28
3.5.27
3.5.26
3.5.25
3.5.24
3.5.23
3.5.22
3.5.21
3.5.20
3.5.19
3.5.18
3.5.17
3.5.16
3.5.15
3.5.14
3.5.13
3.5.12
3.5.11
3.5.10
3.5.9
3.5.8
3.5.7
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
3.4.66
3.4.65
3.4.64
3.4.63
3.4.62
3.4.61
3.4.60
3.4.59
3.4.58
3.4.57
3.4.56
3.4.55
3.4.54
3.4.53
3.4.52
3.4.51
3.4.50
3.4.49
3.4.48
3.4.47
3.4.46
3.4.45
3.4.44
3.4.43
3.4.42
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
3.4.21
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
3.0.0-rc.36
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
1.50.14
1.50.13
1.50.12
1.50.11
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
1.48.0-rc.26
1.48.0-rc.25
1.48.0-rc.24
1.48.0-rc.23
1.48.0-rc.22
1.48.0-rc.21
1.48.0-rc.20
1.48.0-rc.19
1.48.0-rc.18
1.48.0-rc.17
1.48.0-rc.16
1.48.0-rc.15
1.48.0-rc.14
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.
Security advisory:
This version has known vulnerabilities.
View advisories
Current section
Files
Jump to
Current section
Files
documentation/topics/attributes.md
# Attributes
Attributes specify the name, type and properties of a piece of information in a resource.
## Ways of writing attributes
There are two ways to write an attribute:
```elixir
attribute :name, :string, allow_nil?: false
# or ...
attribute :name, :string do
allow_nil? false
end
```
Both ways will work. Though when you're using many options the latter is preferred. This is also true of any other keyword in the Ash DSL, so you can build a flexible yet concise domain model.
For more information on attribute types including composite types and defining your own custom type see `Ash.Type`
You can find a comprehensive of attribute options with detailed descriptions on the `d:Ash.Resource.Dsl.attributes` page.
## Special attributes
In Ash there are 4 special attributes these are:
- `create_timestamp`
- `update_timestamp`
- `integer_primary_key`
- `uuid_primary_key`
These are really just shorthand for an attribute with specific options set. They're outlined below.
### `create_timestamp`
You may recognise this if you have used Ecto before. This attribute will record the time at which each row is created, by default it uses `DateTime.utc_now/1`.
`create_timestamp :inserted_at` is equivalent to an attribute with these options:
```elixir
attribute :inserted_at, :utc_datetime_usec do
writeable? false
private? true
default &DateTime.utc_now/0
match_other_defaults? true
allow_nil? false
end
```
### `update_timestamp`
This is also similar in Ecto. This attribute records the last time a row was updated, also using `DateTime.utc_now/1` by default.
`update_timestamp :updated_at` is equivalent to:
```elixir
attribute :updated_at, :utc_datetime_usec do
writeable? false
private? true
default &DateTime.utc_now/0
updated_default &DateTime.utc_now/0
match_other_defaults? true
allow_nil? false
end
```
### `uuid_primary_key`
This attribute is used in almost every resource. It generates a UUID every time a new record is made.
`uuid_primary_key :id` is equivalent to:
```elixir
attribute :id, :uuid do
writeable? false
default &Ash.UUID.generate/0
primary_key? true
allow_nil? false
end
```
### `integer_primary_key`
Don't use this attribute unless absolutely necessary, there are [a lot of good reasons to not use autoincrementing integer ids](https://www.clever-cloud.com/blog/engineering/2015/05/20/why-auto-increment-is-a-terrible-idea/). If you do, _please_ make sure these resource are only accessed internally and aren't exposed via a public API.
`integer_primary_key :id` is equivalent to:
```elixir
attribute :id, :integer do
writeable? false
generated? true
primary_key? true
allow_nil? false
end
```