Update to allow a Book to have no Publisher.

lib/decentralised_book_index/metadata/book.ex

@@ -373,7 +373,6 @@ defmodule DecentralisedBookIndex.Metadata.Book do
     end
 
     belongs_to :publisher, Metadata.Publisher do
-      allow_nil? false
       public? true
     end
 

lib/decentralised_book_index_web/live/book_live/show.ex

@@ -64,12 +64,14 @@ defmodule DecentralisedBookIndexWeb.BookLive.Show do
         <dt class="mb-2 font-semibold leading-none text-gray-900 dark:text-white">Description</dt>
         <dd class="mb-4 font-light text-gray-500 sm:mb-5 dark:text-gray-400">{@book.description}</dd>
       </dl>
-      <dl>
-        <dt class="mb-2 font-semibold leading-none text-gray-900 dark:text-white">Publisher</dt>
-        <dd class="mb-4 font-light text-gray-500 sm:mb-5 dark:text-gray-400">
-          {@book.publisher.name}
-        </dd>
-      </dl>
+      <%= if not is_nil(@book.publisher) do %>
+        <dl>
+          <dt class="mb-2 font-semibold leading-none text-gray-900 dark:text-white">Publisher</dt>
+          <dd class="mb-4 font-light text-gray-500 sm:mb-5 dark:text-gray-400">
+            {@book.publisher.name}
+          </dd>
+        </dl>
+      <% end %>
       <dl>
         <dt class="mb-2 font-semibold leading-none text-gray-900 dark:text-white">Published</dt>
         <dd class="mb-4 font-light text-gray-500 sm:mb-5 dark:text-gray-400">{@book.published}</dd>

priv/repo/migrations/20250603150057_update_to_allow_a_book_to_have_no_publisher.exs

@@ -0,0 +1,21 @@
+defmodule DecentralisedBookIndex.Repo.Migrations.UpdateToAllowABookToHaveNoPublisher do
+  @moduledoc """
+  Updates resources based on their most recent snapshots.
+
+  This file was autogenerated with `mix ash_postgres.generate_migrations`
+  """
+
+  use Ecto.Migration
+
+  def up do
+    alter table(:books) do
+      modify :publisher_id, :uuid, null: true
+    end
+  end
+
+  def down do
+    alter table(:books) do
+      modify :publisher_id, :uuid, null: false
+    end
+  end
+end

priv/resource_snapshots/repo/books/20250603150057.json

@@ -0,0 +1,227 @@
+{
+  "attributes": [
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"gen_random_uuid()\")",
+      "generated?": false,
+      "primary_key?": true,
+      "references": null,
+      "size": null,
+      "source": "id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "title",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "description",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "published",
+      "type": "date"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "language",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "format",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "page_count",
+      "type": "bigint"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "cover_image_url",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"(now() AT TIME ZONE 'utc')\")",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "inserted_at",
+      "type": "utc_datetime_usec"
+    },
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"(now() AT TIME ZONE 'utc')\")",
+      "generated?": false,
+      "primary_key?": false,
+      "references": null,
+      "size": null,
+      "source": "updated_at",
+      "type": "utc_datetime_usec"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": {
+        "deferrable": false,
+        "destination_attribute": "id",
+        "destination_attribute_default": null,
+        "destination_attribute_generated": null,
+        "index?": false,
+        "match_type": null,
+        "match_with": null,
+        "multitenancy": {
+          "attribute": null,
+          "global": null,
+          "strategy": null
+        },
+        "name": "books_dbi_server_id_fkey",
+        "on_delete": null,
+        "on_update": null,
+        "primary_key?": true,
+        "schema": "public",
+        "table": "dbi_servers"
+      },
+      "size": null,
+      "source": "dbi_server_id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": {
+        "deferrable": false,
+        "destination_attribute": "id",
+        "destination_attribute_default": null,
+        "destination_attribute_generated": null,
+        "index?": false,
+        "match_type": null,
+        "match_with": null,
+        "multitenancy": {
+          "attribute": null,
+          "global": null,
+          "strategy": null
+        },
+        "name": "books_book_editions_registry_id_fkey",
+        "on_delete": null,
+        "on_update": null,
+        "primary_key?": true,
+        "schema": "public",
+        "table": "book_editions_registries"
+      },
+      "size": null,
+      "source": "book_editions_registry_id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "primary_key?": false,
+      "references": {
+        "deferrable": false,
+        "destination_attribute": "id",
+        "destination_attribute_default": null,
+        "destination_attribute_generated": null,
+        "index?": false,
+        "match_type": null,
+        "match_with": null,
+        "multitenancy": {
+          "attribute": null,
+          "global": null,
+          "strategy": null
+        },
+        "name": "books_publisher_id_fkey",
+        "on_delete": null,
+        "on_update": null,
+        "primary_key?": true,
+        "schema": "public",
+        "table": "publishers"
+      },
+      "size": null,
+      "source": "publisher_id",
+      "type": "uuid"
+    }
+  ],
+  "base_filter": null,
+  "check_constraints": [],
+  "custom_indexes": [
+    {
+      "all_tenants?": false,
+      "concurrently": false,
+      "error_fields": [],
+      "fields": [
+        {
+          "type": "string",
+          "value": "title gin_trgm_ops"
+        }
+      ],
+      "include": null,
+      "message": null,
+      "name": "book_title_gin_index",
+      "nulls_distinct": true,
+      "prefix": null,
+      "table": null,
+      "unique": false,
+      "using": "GIN",
+      "where": null
+    }
+  ],
+  "custom_statements": [],
+  "has_create_action": true,
+  "hash": "AA67DC03E5D78606517F268BD28B58521F2000DE3BA531FA48363CCD08CE4475",
+  "identities": [],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.DecentralisedBookIndex.Repo",
+  "schema": null,
+  "table": "books"
+}