Eloquent ORM - 如何在父模型中处理与同一子模型的两个实例的关系

Question

I have a parent model called Journey that should relate to two instances of model-type Address - once for 'origin' and once for 'destination'. I can't work out what's the most efficient way of doing this. I would like to use Laravel's Eloquent ORM with eager-loading to achieve something elegant like the following when I return a journey:

return Journey::with('origin','destination');

I've tried the following:

1) Using Eloquent ORM's one to one relationships

Journey
-------
id
user_id
date

Address
-------
id
journey_id
street
city
zipcode

Observations:

• Requires 'journey_id' in the Address model, meaning I can't really re-use this model for anything other than Journeys
• Address is linked to Journey as a whole, so I can't distinguish between origin and destination instances

2) Using Eloquent ORM's polymorphic relationships

Journey
-------
id
user_id
date

Address
-------
id
street
city
zipcode
addressable_id
addressable_type

Observations:

• I can now re-use the Address model with other models, but...
• Address is still linked to Journey as a whole, so I can't distinguish between origin and destination instances

3) Relating 'journey.origin' or 'journey.destination' by joining it to 'address.id'

Journey
-------
id
user_id
origin (address.id)
destination (address.id)
date

Address
-------
id
street
city
zipcode

Observations:

• I can now distinguish between the origin & destination instances, but...
• I think I have to use fluent queries for the joins, so I don't get origin & destination back as Address models
• There is no link back from the address to the journey

Does anyone have any suggestions for table / relationship structure that makes journey (with origin & destination) insertion and selection as elegant as possible, preferably using Eloquent so that I can utilise my model attributes and functions?

Also, although accessing the addresses through the Journey model will be the primary use case, I'd also like to be able to access the parent Journey through the Address model.

Answer 1

What you should have is:

Database Strucuture

Journey
---------
id
origin_id
destionation_id
user_id
date

Address
---------
id
street
city
zipcode

Then, link your Journey model to Address using a One-to-Many relationship:

Journey.php

class Journey extends Model {
    // ...

    public function origin() {
        return $this->belongsTo('Address');
    }

    public function destination() {
        return $this->belongsTo('Address');
    }
}

Address.php

class Address extends Model {
    // ...

    public function journeysAsOrigin() {
        return $this->hasMany('Journey', 'origin_id');
    }

    public function journeysAsDestination() {
        return $this->hasMany('Journey', 'destination_id');
    }
}