Split the two discussion_id -> post_id migrations into 4 total

migrations/2023_07_08_000000_rename_polls_discussion_id_column.php

@@ -12,16 +12,15 @@
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Database\Schema\Builder;
 
+// Split 1/2 of 2023_07_08_000000_rename_polls_discussion_id_column.php
 return [
     'up' => function (Builder $schema) {
         $schema->table('polls', function (Blueprint $table) {
             $table->dropForeign(['discussion_id']);
-            $table->renameColumn('discussion_id', 'post_id');
         });
     },
     'down' => function (Builder $schema) {
         $schema->table('polls', function (Blueprint $table) {
-            $table->renameColumn('post_id', 'discussion_id');
             $table->foreign('discussion_id')->references('id')->on('discussions')->onDelete('cascade');
         });
     },

migrations/2023_07_08_000000_rename_polls_discussion_id_column_1.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of fof/polls.
+ *
+ * Copyright (c) FriendsOfFlarum.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Schema\Builder;
+
+// Split 2/2 of 2023_07_08_000000_rename_polls_discussion_id_column.php
+return [
+    'up' => function (Builder $schema) {
+        // Do not run this migration if the column was already renamed before the split
+        if ($schema->hasColumn('polls', 'post_id')) {
+            return;
+        }
+
+        $schema->table('polls', function (Blueprint $table) {
+            $table->renameColumn('discussion_id', 'post_id');
+        });
+    },
+    'down' => function (Builder $schema) {
+        $schema->table('polls', function (Blueprint $table) {
+            $table->renameColumn('post_id', 'discussion_id');
+        });
+    },
+];

migrations/2023_07_08_000000_update_polls_discussion_id_to_post_id_values.php

@@ -0,0 +1,87 @@
+<?php
+
+/*
+ * This file is part of fof/polls.
+ *
+ * Copyright (c) FriendsOfFlarum.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Illuminate\Database\Query\JoinClause;
+use Illuminate\Database\Schema\Builder;
+
+// Split 1/2 of 2023_07_08_000001_update_polls_discussion_relation_to_first_post.php
+return [
+    'up' => function (Builder $schema) {
+        $db = $schema->getConnection();
+
+        // Do not run this migration if the values were already updated before the split
+        if ($db->table('migrations')->where('migration', '2023_07_08_000001_update_polls_discussion_relation_to_first_post')->exists()) {
+            return;
+        }
+
+        $db->transaction(function () use ($db) {
+            $prefix = $db->getTablePrefix();
+
+            // Don't run through this step if no rows exist in the polls table
+            if (!$db->table('polls')->exists()) {
+                return;
+            }
+
+            // Update polls whose discussions have a clear first post ID associated
+            $db->table('polls')
+                ->join('discussions', function (JoinClause $join) {
+                    $join->on('polls.post_id', '=', 'discussions.id')
+                        ->where('discussions.first_post_id', '!=', null);
+                })
+                ->update(['polls.post_id' => $db->raw("{$prefix}discussions.first_post_id")]);
+
+            // Update polls whose discussions have a null first post ID associated
+            $firstPosts = $db->table('posts')
+                ->where('number', '=', 1);
+
+            $db->table('polls')
+                ->join('discussions', function (JoinClause $join) {
+                    $join->on('polls.post_id', '=', 'discussions.id')
+                        ->where('discussions.first_post_id', '=', null);
+                })
+                ->leftJoinSub($firstPosts, 'first_posts', function (JoinClause $join) {
+                    $join->on('first_posts.discussion_id', '=', 'discussions.id');
+                })
+                ->update(['polls.post_id' => $db->raw("{$prefix}first_posts.id")]);
+
+            // Delete polls that don't have an associated post
+            $deletingPolls = $db->table('polls')
+                ->where('post_id', 0);
+            $count = $deletingPolls->count();
+
+            if ($count > 0) {
+                resolve('log')->warning("[fof/polls] deleting {$deletingPolls->count()} polls with no associated post");
+                resolve('log')->warning("[fof/polls] |> #{$deletingPolls->pluck('id')->join(', #')}");
+            } else {
+                resolve('log')->info('[fof/polls] no polls to delete in v2 migration');
+            }
+
+            $deletingPolls->delete();
+        });
+    },
+    'down' => function (Builder $schema) {
+        $db = $schema->getConnection();
+
+        $db->transaction(function () use ($db) {
+            $prefix = $db->getTablePrefix();
+
+            // Don't run through this step if no rows exist in the polls table
+            if (!$db->table('polls')->exists()) {
+                return;
+            }
+
+            // Go back to using discussion IDs. The discussion ID will always exist since the posts' foreign key cascades on delete.
+            $db->table('polls')
+                ->join('posts', 'polls.post_id', '=', 'posts.id')
+                ->update(['polls.post_id' => $db->raw("{$prefix}posts.discussion_id")]);
+        });
+    },
+];

migrations/2023_07_08_000001_update_polls_discussion_relation_to_first_post.php

@@ -9,80 +9,17 @@
  * file that was distributed with this source code.
  */
 
-use Illuminate\Database\Query\JoinClause;
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Database\Schema\Builder;
 
+// Split 2/2 of 2023_07_08_000001_update_polls_discussion_relation_to_first_post.php
 return [
     'up' => function (Builder $schema) {
-        $db = $schema->getConnection();
-
-        $db->transaction(function () use ($db) {
-            $prefix = $db->getTablePrefix();
-
-            // Don't run through this step if no rows exist in the polls table
-            if (!$db->table('polls')->exists()) {
-                return;
-            }
-
-            // Update polls whose discussions have a clear first post ID associated
-            $db->table('polls')
-                ->join('discussions', function (JoinClause $join) {
-                    $join->on('polls.post_id', '=', 'discussions.id')
-                        ->where('discussions.first_post_id', '!=', null);
-                })
-                ->update(['polls.post_id' => $db->raw("{$prefix}discussions.first_post_id")]);
-
-            // Update polls whose discussions have a null first post ID associated
-            $firstPosts = $db->table('posts')
-                ->where('number', '=', 1);
-
-            $db->table('polls')
-                ->join('discussions', function (JoinClause $join) {
-                    $join->on('polls.post_id', '=', 'discussions.id')
-                        ->where('discussions.first_post_id', '=', null);
-                })
-                ->leftJoinSub($firstPosts, 'first_posts', function (JoinClause $join) {
-                    $join->on('first_posts.discussion_id', '=', 'discussions.id');
-                })
-                ->update(['polls.post_id' => $db->raw("{$prefix}first_posts.id")]);
-
-            // Delete polls that don't have an associated post
-            $deletingPolls = $db->table('polls')
-                ->where('post_id', 0);
-            $count = $deletingPolls->count();
-
-            if ($count > 0) {
-                resolve('log')->warning("[fof/polls] deleting {$deletingPolls->count()} polls with no associated post");
-                resolve('log')->warning("[fof/polls] |> #{$deletingPolls->pluck('id')->join(', #')}");
-            } else {
-                resolve('log')->info('[fof/polls] no polls to delete in v2 migration');
-            }
-
-            $deletingPolls->delete();
-        });
-
         $schema->table('polls', function (Blueprint $table) {
             $table->foreign('post_id')->references('id')->on('posts')->onDelete('cascade');
         });
     },
     'down' => function (Builder $schema) {
-        $db = $schema->getConnection();
-
-        $db->transaction(function () use ($db) {
-            $prefix = $db->getTablePrefix();
-
-            // Don't run through this step if no rows exist in the polls table
-            if (!$db->table('polls')->exists()) {
-                return;
-            }
-
-            // Go back to using discussion IDs. The discussion ID will always exist since the posts' foreign key cascades on delete.
-            $db->table('polls')
-                ->join('posts', 'polls.post_id', '=', 'posts.id')
-                ->update(['polls.post_id' => $db->raw("{$prefix}posts.discussion_id")]);
-        });
-
         $schema->table('polls', function (Blueprint $table) {
             $table->dropForeign(['post_id']);
         });