如何在Laravel模型之间建立正确的关系

Question

So I have two tables named 'customers' and 'billing_addresses'. I also have two models named 'Customer' and 'BillingAddress'.

In the billing_addresses table, there are multiple addresses, each having an 'id'.

In the customers table, each customer has an 'billing_address_id' value corresponding to one of the entries in the billing_addresses table.

What I managed to create so far is:

// Customer relationship method(in the model file)
   public function address()
{
    return $this->hasOne('App\BillingAddress','id');
}


/////////

// BillingAddress relationship method(in the model file)


 public function customer()
    {
        return $this->hasMany('App\Customer','id');
    }

I am indeed getting the right data when I do something like Customer::with('address');

but I feel like there is a better approach for all this as I'm also getting

BadMethodCallException

Call to undefined method 

Illuminate\Database\Eloquent\Relations\HasOne::getForeignKey()  

when I try to filter with datatables(can't tell if its related but first I'd want to have the best approach on the relationships).

Thank you!

Answer 1

A custom can have multiple billing addresses. So it customer can have many addresses and an address belongs to a customer.

// Customer Model
public function addresses()
{
    return $this->belongsTo('App\BillingAddress', 'customer_id');
}


// BillingAddress Model
public function customer()
{
    return $this->hasMany('App\Customer', 'billing_address_id');
}

Then you can do : Customer::with('addresses')->get();

Secondly, make sure you are passing correct foreign key column as second parameter to the relationship methods. See documentation for reference

The second error is probably causing because of incorrect foreign key column passed as second argument.

Answer 2

What you want to achieve is this:

// Customer Model
public function address()
{
    return $this->belongsTo('App\BillingAddress');
}


// BillingAddress Model
public function customer()
{
    return $this->hasMany('App\Customer');
}

You need the belongsTo on your Customer Model because you have the Billing id stored within the Customer table. Eloquent will automatically match the billing id to the foreign Key in your customer model. You just need to follow Eloquente naming conventions for foreign keys. Look here for more infos.

Eloquent Relations