Update Schema Definition

• Change the embedded schema field type from :string to {:array, :string}

embedded_schema do
  field :tags, {:array, :string}
end

Create Migration

• Generate migration: mix ecto.gen.migration update_tags_field

Implement Up Migration (String → Array)

execute("""
UPDATE my_table
SET embedded_schema_field = jsonb_set(
  embedded_schema_field,
  '{tags}',
  to_jsonb(string_to_array((embedded_schema_field->>'tags'), ','))
)
WHERE embedded_schema_field ? 'tags';
""")

Implement Down Migration (Array → String)

execute("""
UPDATE my_table
SET embedded_schema_field = jsonb_set(
  embedded_schema_field,
  '{tags}',
  to_jsonb(array_to_string((embedded_schema_field->'tags')::text[], ','))
)
WHERE embedded_schema_field ? 'tags';
""")

Key Points

• Embedded schemas are stored in JSONB columns, not separate tables
• Use jsonb_set() to update specific nested keys safely
• Use string_to_array() and array_to_string() for type conversion
• Use to_jsonb() to maintain JSONB format compatibility
• Update any existing queries to handle the new list type