create

create

A create action on a store resource. Defines how new records are inserted, which fields are accepted, what validations run before insert, and what changes apply during the operation. Compiles to an Ash Framework create action at runtime.

When to use

Use create when you need to:

• Insert new records into a store resource
• Restrict which fields can be set during creation
• Validate input data before persisting (e.g., required fields, format checks)
• Apply computed changes during insertion (e.g., set a default status, generate a slug)

Every resource should have at least one create action. Use defaults: [create] for a standard create action that accepts all fields, or define a named action with explicit accept and validate blocks for fine-grained control.

Syntax

resource <resource_name>
  create <action_name>
    accept: [<field1>, <field2>, ...]
    validate <rule>
    change <function>

Parameters

Parameter	Required	Description
action_name	Yes	Bare identifier naming this action. Multiple create actions can exist on a single resource.
accept	No	List of field names that this action accepts. If omitted, all non-primary-key fields are accepted.
validate	No	Validation rule applied before insert. Can appear multiple times.
change	No	Mutation function applied during insert. Can appear multiple times.

Validation rules

Rule	Description	Example
present([fields])	Fields must be non-nil	validate present([title, body])
format(field, pattern)	Field must match a regex pattern	validate format(email, ~r/@/)
length(field, min, max)	String length within range	validate length(name, 1, 100)
compare(field, op, value)	Numeric comparison	validate compare(age, :gt, 0)

Examples

Simple create with accepted fields

resource document
  id as uuid, is primary_key
  title as text, is required
  content as text
  status as text, default: "draft"
  timestamps

  create add_document
    accept: [title, content]

The status field is not in the accept list, so it always gets its default value of "draft" when a new record is created through this action.

Create with validation

resource user
  id as uuid, is primary_key
  email as text, is required
  username as text, is required
  bio as text
  timestamps

  create register
    accept: [email, username, bio]
    validate present([email, username])
    validate format(email, ~r/@/)
    validate length(username, 3, 30)

Multiple create actions on one resource

resource ticket
  id as uuid, is primary_key
  title as text, is required
  priority as text, default: "normal"
  source as text, is required
  timestamps

  create from_web
    accept: [title, priority]
    change set_attribute(source, "web")

  create from_api
    accept: [title, priority]
    change set_attribute(source, "api")

  create from_email
    accept: [title]
    change set_attribute(source, "email")
    change set_attribute(priority, "normal")

Governance

Create actions are governed effects. When a machine executes a create action:

1. The governance interpreter checks the db capability
2. The action is subject to any policy blocks on the resource
3. The operation is recorded in the behavioral ledger with the action name, accepted fields, and result
4. The machine’s ensures > permissions section can restrict or require approval for data writes

Translations

Language	Keyword
English	create
Spanish	crear
French	creer
German	erstellen
Japanese	作成
Chinese	创建
Korean	생성

See also

• resource - Resource declarations
• read - Read actions for querying data
• update - Update actions for modifying records
• destroy - Destroy actions for deleting records
• policy - Authorization policies on actions