Pivot tables and belongsToMany in Laravel

Because I can never remember how pivot tables work with a many-to-many relationship.

Using Blog Posts and Tags as an example:

Models:

Post

Tags

Tables:

Post

Tags

Post_Tag

In the Post_Tag migration

$table->id();
$table->foreignIdFor(Post::class, ‘optional_column_name’)->constrained()->cascadeOnDelete();
$table->foreignIdFor(Tag::class);

Then in the Post model

Public function tags() {
	return $this->belongsToMany(Tag::class);
}

Or if you need to specify the column name for the pivot

Public function tags() {
	return $this->belongsToMany(Tag::class, foreignPivotKey: “unusual_column_name_for_post_id”);
}

Then in the Tag model

Public function posts() {
	return $this->belongsToMany(Post::class);
}

Public function posts() {
	return $this->belongsToMany(Post::class, relatedPivotKey: “unusual_column_name_for_post_id”);
}

Note