>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3379184. --> Reported by: [dinarcon](https://www.drupal.org/user/909522) >>> <h3 id="summary-problem-motivation">Problem/Motivation</h3> <p>CSV files can have column names with spaces. This produces unintended effects when using the default ID map plugin: <code>\Drupal\migrate\Plugin\migrate\id_map\Sql</code></p> <p>On PHP 8.1, you get the following warning when rolling back a migration that has a column name with a space.<br> <code>[warning] Undefined array key "Some Header with Space" Sql.php:232</code></p> <p>That happens in <code>\Drupal\migrate\Plugin\migrate\id_map\Sql::getSourceIdsHash</code></p> <p>This is because the column is used an alias for the field to be added in the SELECT statement. And aliases are spaced in `\Drupal\Core\Database\Connection::escapeAlias`. Per the method description: &ldquo;Escapes an alias name string. Force all alias names to be strictly alphanumeric-plus-underscore&rdquo;.</p> <h4 id="summary-steps-reproduce">Steps to reproduce</h4> <ol> <li>In a site running PHP 8.1 or higher, create a CSV migration that has a column name with a space used as ID. For example: "Project ID".</li> <li>Import the migration.</li> <li>Rollback the migration.</li> </ol> <h3 id="summary-proposed-resolution">Proposed resolution</h3> <p>Document that column names have to be alphanumeric characters or underscores.</p> <h3 id="summary-remaining-tasks">Remaining tasks</h3> <ul> <li>Create and review patch.</li> <li>Evaluate if we need to mention that this happens when the ID map uses or extends <code>\Drupal\migrate\Plugin\migrate\id_map\Sql</code>.</li> <li>Shall we file a similar issue in <a href="https://www.drupal.org/project/migrate_plus">https://www.drupal.org/project/migrate_plus</a> since this could also happen in JSON files which that module supports?</li> <li>Shall we create an issue in Drupal core to document this as part of `\Drupal\migrate\Plugin\MigrateSourceInterface::getIds`?</li> </ul> <h3 id="summary-ui-changes">User interface changes</h3> <p>None.</p> <h3 id="summary-api-changes">API changes</h3> <p>None.</p> <h3 id="summary-data-model-changes">Data model changes</h3> <p>None.</p> <h3 id="summary-data-model-changes">Notes</h3> <p>This issue was discussed in slack <a href="https://drupal.slack.com/archives/C226VLXBP/p1689078305424729">https://drupal.slack.com/archives/C226VLXBP/p1689078305424729</a></p> <p>For reference, below is a comment with some of the research into the issue.</p> <ol> <li>In \Drupal\migrate\Plugin\migrate\id_map\Sql::deleteDestination there is a call to \Drupal\migrate\Plugin\migrate\id_map\Sql::lookupSourceId</li> <li>In there, Each source key is added to the query via $query-&gt;addField('map', $id_map_field_name, $source_field_name);</li> <li>Later in the same method, there is a $query-&gt;execute() which eventually reaches \Drupal\Core\Database\Query\Select::__toString</li> <li>When the query is assembling the list of (query) fields to be added in the SELECT statement via the foreach ($this-&gt;fields as $field) loop, there is a call to \Drupal\Core\Database\Connection::escapeAlias</li> <li>And in there, the alias is escaped using preg_replace('/[^A-Za-z0-9_]+/', '', $field). Per the method description: &ldquo;Escapes an alias name string. Force all alias names to be strictly alphanumeric-plus-underscore&rdquo;. In there Some Value gets transformed to SomeValue</li> <li>Back in deleteDestination , there is a call to $this-&gt;getSourceIdsHash($source_id_values)</li> <li>In \Drupal\migrate\Plugin\migrate\id_map\Sql::getSourceIdsHash, the $source_id_values argument is keyed by the escaped field alias. But the call to $this-&gt;sourceIdFields() returns the unescaped raw source key.</li> <li>So, in $source_id_values[$field_name] , the raw Some Value does not exists as a key. By then, the key has changed to SomeValue. And this is what triggers the error.</li> <li>And this probably has other unintended consequences. Also in getSourceIdsHash , there is a call to hash which receives $source_id_values as an argument. At this point, I stopped investigating.</li> </ol>