如何修复 Laravel 急切加载不适用于自定义外键

Question

Listing and Sub_Category have a one to many relationship. Listing belongs to one sub_category and sub_category has many listings.

I have a column on my listings table 'sub_catgory_id' and I have also specified the foreign key in my relationship

Listing.php Model
public function sub_category()
{
    return $this->belongsTo('App\Sub_Category', 'sub_category_id', 'id');
}

Trying to get all listings associated with a sub category

return $sub_category = \App\Sub_Category::with('listing')->get()

I get this error => Column not found: 1054 Unknown column 'listings.sub__category_id' in 'where clause'.

I know eloquent is checking for sub__category_id (double underscore) but I am already far into this project and would like to leave it as sub_category_id (single underscore). Any ideas about how this can be achieved?

Answer 1

I finally figured it out a fix. You can camelCase your model. So in my case I renamed my model from Sub_Category to subCategory so eloquent checks sub_category_id.

Answer 2

I think you should set like :

1 .Listening.php:

public function sub_category()
{
    return $this->belongsTo('App\Sub_Category', 'id', 'sub_category_id');
}

2.Sub_Category.php :

public function listing()
{
    return $this->belongsTo('App\Listening', 'sub_category_id','id');
}

By laravel document in set Relationships we set first foreign_key then local_key like this (Example get from laravel website):

return $this->hasOne('App\Phone', 'foreign_key', 'local_key');

Answer 3

You can try below code:

1.Sub_Category.php(Model)

public function listimg() {
    return $this->belongsTo('App\Listening');
}

2.Contoller
$sub_category = \App\Sub_Category::with('listing')->get();

Answer 4

For the custom foreign key column you have pass two additional arguments for the function hasMany('Model', 'fk', 'pk') with the foreign key column name and the reference key column name.

class Category extends Model
{
    protected $table = 'categories';
    public function contents(){
        return $this->hasMany('App\Content', 'sub_cat_id', 'id');
    }
}
class Content extends Model
{
    //
    protected $table = 'contents';
    public function category(){
        return $this->belongsTo('App\Category');
    }
}

 Schema::create('categories', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->integer('user_id');
            $table->integer('parent_id');
            $table->string('title');
            $table->timestamps();
        });

Schema::create('contents', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->integer('app_id');
            $table->integer('cat_id');
            $table->bigInteger('sub_cat_id')->unsigned();
            $table->integer('content_type');
            $table->text('content');
            $table->text('title');
            $table->timestamps();
            $table->foreign('sub_cat_id')->references('id')->
            on('categories')->onDelete('cascade');

        });