How to solved in Laravel relations null value

Question

Im tru to use to last version of laravel and i have small problem with Laravel relationship One to Many Im try to connect products with categories

This is my code of Product model

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

this is my code of Category model

public function products()
{
    return $this->hasMany('App\Product');
}

This is my code in controller

$products = Product::with('categories')->get();
    dd($products);

this is my code from migration files

Schema::create('products', function (Blueprint $table) {
        $table->id();
        $table->unsignedBigInteger('category_id');
        $table->string('name')->unique();
        $table->string('slug')->unique();
        $table->string('keywords')->nullable();
        $table->string('price');
        $table->text('description')->nullable();
        $table->text('image')->nullable();
        $table->timestamps();
        $table->foreign('category_id')->references('id')->on('categories');
    });

Schema::create('categories', function (Blueprint $table) {
        $table->id();
        $table->string('name')->unique();
        $table->string('slug')->unique();
        $table->string('keywords')->nullable();
        $table->timestamps();
    });[![enter image description here][1]][1]

If someone know how to solved this problem I'll be very grateful

belongsTo() returns a single record or null. The name categories suggests many (it's plural). Change the name to category, or change the method to hasMany() or belongsToMany(). You should never use a plural name for single records, or a singular name for multiple records. — Tim Lewis
– Tim Lewis, Commented May 6, 2020 at 18:35
Eloquent determines the default foreign key name by examining the name of the relationship method and suffixing the method name with a _ followed by the name of the primary key column. So I think eloquent is determinig that the fk is categories_id intead category_id — porloscerros Ψ
– porloscerros Ψ, Commented May 6, 2020 at 18:45
@porloscerrosΨ I thought it was based off the name of the Model, not the method. Category should be correctly mapped to category_id. Ah; maybe not, but the method name is wrong; should be category() not categories() for a belongsTo() or hasOne() method. — Tim Lewis
– Tim Lewis, Commented May 6, 2020 at 18:47
@TimLewis I agree that the method name should be category and not categories since it's a belongsTo relationship. I just copied what is in the documentation regarding One To Many (Inverse). Eloquent will take the "snake case" name of the owning model and suffix it with _id for hasMany and hasOne relationshps, but for belogsTo, will examine the name of the relationship method. The other thing I added to the comment is just a guess, it could also give an exception by not finding the column. — porloscerros Ψ
– porloscerros Ψ, Commented May 6, 2020 at 19:02

Omer YILMAZ · Accepted Answer · 2020-05-06 19:04:51Z

3

Firstly relation comes with eager loading. Please update your codes according to single usage

In Product Model

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

In Controller

$products = Product::with('category')->get();
dd($products[0]->category);

edited May 6, 2020 at 19:04

answered May 6, 2020 at 18:48

Omer YILMAZ

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6 Comments

Tim Lewis Over a year ago

While with() is not related to the issue here, saying to remove it is just wrong. If you're loading all Product, then accessing a relationship, you want to use with() to avoid an N+1 query execution issue. Product::with('category')->get(); is the correct syntax here.

Omer YILMAZ Over a year ago

Ok updated, I already know this, i just want to show this is not 'with' issue, this is singular plural issue

Tim Lewis Over a year ago

Yup; make sense. Just keep in mind, you can't use ->all() after another call, you need to use ->get() or you get the error "Call to undefined method Illuminate/Database/Eloquent/Builder::all()", so again, the correct syntax is Product::with('category')->get();

Omer YILMAZ Over a year ago

:) this area is not as ide, so i just add with and it is working yay! :) I updated

Tim Lewis Over a year ago

Haha yeah, that's an easy error to make. Typically, I never use ::all(), since it's not available once chained, and just stick with ::get(), even for all records. Like Product::get() and Product::all() will return the same thing, but Product::with(...)->all(); is an error, where Product::with(...)->get(); is not :)

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M. Tahir · Accepted Answer · 2020-05-06 18:48:46Z

2

You are telling relationships name is categories, so laravel belongsTo will look categories_id instead category_id.

You can rename your relationships name as category() or give your relationships foreign key to laravel like this;

return $this->belongsTo('App\Category', 'category_id', 'id');

answered May 6, 2020 at 18:48

M. Tahir

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