Laravel 5.6 OneToOne relation not working - php

Question

I have a BuildingImage model with a OneToOne relation to BuildingType:
BuildImage Model:
/**
* Get the source type of the Building Image.
*/
public function type()
{
return $this->hasOne('App\BuildingType');
}
BuildingType Model:
/**
* Get the Building Image that owns the building type.
*/
public function buildingImage()
{
return $this->belongsTo('App\BuildingImage');
}
My tables:
building_images table -> source is the building type id
building_types table
When I try to do this in my controller just to test:
(an ImageRequest has one or more Builings and a Building has one BuildingType)
$imageRequest = ImageRequest::findOrFail($id);
$buildings = $imageRequest->buildingImages;
foreach ($buildings as $building) {
dd($building->type);
}
I get this error:
SQLSTATE[42S22]: Column not found: 1054 Unknown column
'building_types.building_image_id' in 'where clause' (SQL: select *
from building_types where building_types.building_image_id = 45
and building_types.building_image_id is not null limit 1)
What am I doing wrong here?

Answer 1

That's because by default laravel will look for a primary key named {model}_id, and given that you are using a different column name (source), you need to specify when defining the relationship:
As the documentation states:
Eloquent determines the foreign key of the relationship based on the model name. In this case, the Phone model is automatically assumed to have a user_id foreign key. If you wish to override this convention, you may pass a second argument to the hasOne method:
return $this->hasOne('App\Phone', 'foreign_key');
Additionally, Eloquent assumes that the foreign key should have a value matching the id (or the custom $primaryKey) column of the parent. In other words, Eloquent will look for the value of the user's id column in the user_id column of the Phone record. If you would like the relationship to use a value other than id, you may pass a third argument to the hasOne method specifying your custom key:
return $this->hasOne('App\Phone', 'foreign_key', 'local_key');
Now that that is clear. Let's talk about the relationship itself.
You are defining that a BuildImage has one BuildingType. But with that logic, the foreign key should be stored in the building_types table, and not the other way around (source column appears in the building_images table). And -I'm just assuming that- many BuildImage can belongs to an specific BuildingType. So, if this assumption is correct:
a BuildImage belongs to a specific BuildingType.
a BuildinType can be specify in many BuildImages
So, you should define your relationship like this:
BuildImage.php
public function type()
{
return $this->belongsTo('App\BuildingType', 'source');
}
BuildingType.php
public function images()
{
return $this->hasMany(BuildingImage::class, 'source');
}

Answer 2

Your BuildImage model should be
/**
* Get the source type of the Building Image.
*/
public function type() {
return $this->hasOne('App\BuildingType',"id","source");
}
And BuildingType Model should be
/**
* Get the Building Image that owns the building type.
*/
public function buildingImage()
{
return $this->belongsTo('App\BuildingImage',"source","id");
}
This should work.
For more info have a look
https://laravel.com/docs/5.7/eloquent-relationships#one-to-one

Answer 3

Have you tried to indicate the index ID like this?
public function buildingImage()
{
return $this->belongsTo('App\BuildingImage', 'image_request_id');
}
Eloquent determines the foreign key of the relationship based on the
model name. In this case, the Phone model is automatically assumed to
have a user_id foreign key. If you wish to override this convention,
you may pass the second argument to the hasOne method:
return $this->hasOne('App\Phone', 'foreign_key');
https://laravel.com/docs/5.7/eloquent-relationships#one-to-one