php - Dropping column with foreign key Laravel error: General error: 1025 Error on rename

Question

I've created a table using migration like this:

public function up()
{
    Schema::create('despatch_discrepancies',  function($table) {
        $table->increments('id')->unsigned();
        $table->integer('pick_id')->unsigned();
        $table->foreign('pick_id')->references('id')->on('picks');
        $table->integer('pick_detail_id')->unsigned();
        $table->foreign('pick_detail_id')->references('id')->on('pick_details');
        $table->integer('original_qty')->unsigned();
        $table->integer('shipped_qty')->unsigned();
    });
}

public function down()
{
    Schema::drop('despatch_discrepancies');
}

I need to change this table and drop the foreign key reference & column pick_detail_id and add a new varchar column called sku after pick_id column.

So, I've created another migration, which looks like this:

public function up()
{
    Schema::table('despatch_discrepancies', function($table)
    {
        $table->dropForeign('pick_detail_id');
        $table->dropColumn('pick_detail_id');
        $table->string('sku', 20)->after('pick_id');
    });
}

public function down()
{
    Schema::table('despatch_discrepancies', function($table)
    {
        $table->integer('pick_detail_id')->unsigned();
        $table->foreign('pick_detail_id')->references('id')->on('pick_details');
        $table->dropColumn('sku');
    });
}

When I run this migration, I get the following error:

[IlluminateDatabaseQueryException]
SQLSTATE[HY000]: General error: 1025 Error on rename of './dev_iwms_reboot/despatch_discrepancies' to './dev_iwms_reboot/#sql2-67c-17c464' (errno: 152) (SQL: alter table despatch_discrepancies drop foreign key pick_detail_id)

[PDOException]
SQLSTATE[HY000]: General error: 1025 Error on rename of './dev_iwms_reboot/despatch_discrepancies' to './dev_iwms_reboot/#sql2-67c-17c464' (errno: 152)

When I try to reverse this migration by running php artisan migrate:rollback command, I get a Rolled back message, but it's not actually doing anything in the database.

Any idea what might be wrong? How do you drop a column that has a foreign key reference?

Answer 1

You can use this:

$table->dropForeign(['pick_detail_id']);
$table->dropColumn('pick_detail_id');

If you take a peak at dropForeign source, it will build the foreign key index name for you if you pass the column name as an array.