Ash Elixir•2y ago

How to assign a default value to existing rows via Ash.postgres generated migration code

When a non-null column is added, is there a way to specify a default value to assign to the new column for existing records? I believe in Ecto, it's done something like this, but I'm curious if this can be done through Ash DSL.

add :new_field, :string, default: "default value"

add :new_field, :string, default: "default value"

If it makes a difference, the new column in my case is a source attribute for a relationship as in something like this. (So manually adding default: "default value" actually causes a foreign_key_violation., which is a different issue on its own.)

    belongs_to :theme, Items.Theme do
      api Items
      allow_nil? false
      destination_attribute :destination_new_field
      source_attribute :new_field
      attribute_type :integer
    end

    belongs_to :theme, Items.Theme do
      api Items
      allow_nil? false
      destination_attribute :destination_new_field
      source_attribute :new_field
      attribute_type :integer
    end

2 Replies

ZachDaniel•2y ago

For that one if you define the theme_id attribute yourself you can then set a default Then set define_attribute false to prevent the relationship from trying to also add that attribute m

JasonOP•2y ago

Okay. Thank you!

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How to assign a default value to existing rows via Ash.postgres generated migration code

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