belongs-to-through

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Laravel Eloquent BelongsToThrough relationships

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Laravel Eloquent BelongsToThrough relationships

BelongsToThrough

This inverse version of HasManyThrough allows BelongsToThrough relationships with unlimited intermediate models.

Supports Laravel 5.0+.

Installation

composer require staudenmeir/belongs-to-through:"^2.5"

Use this command if you are in PowerShell on Windows (e.g. in VS Code):

composer require staudenmeir/belongs-to-through:"^^^^2.5"

Versions

Laravel	Package
13.x	2.18
12.x	2.17
11.x	2.16
10.x	2.13
9.x	2.12
8.x	2.11
7.x	2.10
6.x	2.6
5.x	2.5

Consider this HasManyThrough relationship:
Country → has many → User → has many → Post

php

class Country extends Model
{
    public function posts()
    {
        return $this->hasManyThrough(Post::class, User::class);
    }
}

Use the BelongsToThrough trait in your model to define the inverse relationship:
Post → belongs to → User → belongs to → Country

php

class Post extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function country(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(Country::class, User::class);
    }
}

You can also define deeper relationships:
Comment → belongs to → Post → belongs to → User → belongs to → Country

Supply an array of intermediate models as the second argument, from the related (Country) to the parent model (Comment):

php

class Comment extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function country(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(Country::class, [User::class, Post::class]);
    }
}

Custom Foreign Keys

You can specify custom foreign keys as the fifth argument:

php

class Comment extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function country(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(
            Country::class,
            [User::class, Post::class], 
            foreignKeyLookup: [User::class => 'custom_user_id']
        );
    }
}

Custom Local Keys

You can specify custom local keys for the relations:

VendorCustomerAddress → belongs to → VendorCustomer in VendorCustomerAddress.vendor_customer_id VendorCustomerAddress → belongs to → CustomerAddress in VendorCustomerAddress.address_id

You can access VendorCustomer from CustomerAddress by the following

php

class CustomerAddress extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function vendorCustomer(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(
            VendorCustomer::class,
            VendorCustomerAddress::class,
            foreignKeyLookup: [VendorCustomerAddress::class => 'id'],
            localKeyLookup: [VendorCustomerAddress::class => 'address_id'],
        );
    }    
}

Table Aliases

If your relationship path contains the same model multiple times, you can specify a table alias (Laravel 6+):

php

class Comment extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function grandparent(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(
            Comment::class,
            Comment::class . ' as alias',
            foreignKeyLookup: [Comment::class => 'parent_id']
        );
    }
}

Use the HasTableAlias trait in the models you are aliasing:

php

class Comment extends Model
{
    use \Znck\Eloquent\Traits\HasTableAlias;
}

Soft Deleting

By default, soft-deleted intermediate models will be excluded from the result. Use withTrashed() to include them:

php

class Comment extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function country(): \Znck\Eloquent\Relations\BelongsToThrough
    {
        return $this->belongsToThrough(Country::class, [User::class, Post::class])
            ->withTrashed('users.deleted_at');
    }
}

class User extends Model
{
    use SoftDeletes;
}