In Drupal 8 I am trying to insert some data in my custom table. While executing query I am getting error:

InvalidArgumentException: Placeholders must have a trailing [] if they are to be expanded with an array of values. in Drupal\Core\Database\Connection->expandArguments()

Please find my code below:

$qt = new \stdClass();
$qt->name = 'test name';
$qt->machine_name = 'test machine name';
$qt->settings = array('setting1'=>value1, 'setting2'=>value2);

$query = \Drupal::database()->insert('my_custom_table');

If I am giving values like below it is working. Please help me whats wrong with above code.

  • FYI, the fields method can contain associative arrays in a ['key' => 'value'] format
    – Eyal
    Commented Jun 23, 2016 at 23:11

3 Answers 3


This is all explained in the Drupal documentation. If you are forming a query that can take an array of arguments, then the (arbitrary) placeholder string needs to indicate this. So a placeholder of :column will only work for a single value, but if you want to use an array of values you need to use the syntax :column[].

See https://www.drupal.org/docs/drupal-apis/database-api/static-queries#placeholder-arrays

Specifically, from the documentation, you can use (for example):

$result = $database->query("SELECT * FROM {mytable} WHERE id IN (:ids[])", [':ids[]' => [13, 42, 144]]);

OR you can use (for example):

$result = $database->query("SELECT * FROM {mytable} WHERE id IN (:ids_1, :ids_2, :ids_3)", [
  ':ids_1' => 13, 
  ':ids_2' => 42, 
  ':ids_3' => 144,

But you CANNOT use (for example):

$result = $database->query("SELECT * FROM {mytable} WHERE id IN (:ids)", [':ids' => [13, 42, 144]]);

because in this case you're passing in an array ( [13, 42, 144] ) but the placeholder ( :ids ) does not use the proper syntax for array placeholders.


That issue got resolved. It was regarding passing array in to the db. Added serialise function resloved the issue.


that also happen to me when adding a string to an expected int so casting was necessary


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.