In Laravel, there are foreignId and foreignIdFor functions that can be used to define a foreign key in a migration file. Imagine having a "post" model that has a relation with "user" model. The relationship will be "post" belong to the "user".
Before having the foreignIdFor function, the code to define a foreign key is quite long and prote for error.
Before Using foreignIdFor Function
Before having the foreignIdFor function, the code to define a foreign key is quite long and prote for error.
<?php
Schema::table('posts', function (Blueprint $table) {
$table->unsignedBigInteger('user_id');
$table->foreign('user_id')->references('id')->on('users');
});After Using foreignIdFor Function
Now you can update the code above with the use of "foreignId" function.
<?php
Schema::table('posts', function (Blueprint $table) {
$table->foreignId('user_id')->constrained();
});If you are not sure with the key "user_id" or any other keys that may be internally used by Laravel then you can make use of the "foreignIdFor" function and pass in the Eloquent class like below.
<?php
Schema::table('posts', function (Blueprint $table) {
$table->foreignIdFor(User::class)->constrained();
});Now when you run "php artisan migrate" you will see the foreign key above defined in the table column definition.
