Create a json file containing data needed to drop a foreign key

[ajcastro]

For example we are developing a blog app. The tables involved are users, tags and posts tables.
Migration Files:
20180101_create_users_table

$table->increments('id');
$table->string('name');

20180101_create_tags_table

$table->increments('id');
$table->string('name');

20180101_create_posts_table

  $table->increments('id');
  Fk::make($table)->add('user_id');
  Fk::make($table)->add('tag_id');
  $table->string('title');
  $table->string('body');

This should generate a json of data that is needed when deleting the foreign key.
Those json files will be saved in directory database/foreign_keys/ and the json filename would be the migration_file_name.json.
So when we run the above migration it will create a file database/foreign_keys/20180101_create_posts_table.json. One json file per migration file. Only 20180101_create_posts_table.json is created because it is the only migration file that calls Fk::make().

The data needed to drop a foreign key is the:

• table
• foreign key name.
  Sample Dropping of foreign key :

Schema::table('posts', function ($table) {
  $table->dropForeignKey('the_foreign_key_name');
});

Sample json file format:

[{
"table" : "posts",
"foreign_key_names: ["posts_user_id_foreign_key", "posts_tag_id_foreign_key"]
}]

It is an array of objects, because it can be possible that one migration file can involve many tables.

The code will be placed in the Fk::migrate() method.