Join tables without mixing variables

You can select only the columns you need:

return $this->hasMany(Contracts::class)
    ->selectRaw('contracts.*')
    ->leftJoin('customers','customers.id','=','customers_id');

Unfortunately when there are conflicting column names PDO (the underlying PHP classes Laravel Eloquent is built upon) will override conflicting columns.

Don't mix relationships and joins together.

Also when you have to use join for join tables then everytime use select and for most case just for main table as select('main_table.*')

I commented on a GitHub issue yesterday about this PDO limitation:

https://github.com/laravel/framework/issues/35019#issuecomment-718804783

If you are running MySQL 8 locally you can try check this code:

<?php

$sql =<<<SQL
WITH `company` AS (
    SELECT 1 AS `companyID`, 'Company A' AS `alias`
    UNION
    SELECT 2, 'Company B'
    UNION
    SELECT 3, 'Company C'
),
`company_site` AS (
    SELECT 1 AS `companyID`, 'foo' AS `alias`
    UNION
    SELECT 2, 'bar'
    UNION
    SELECT 3, 'baz'
)
SELECT *
FROM
    company as c
    JOIN company_site as cs
        ON c.companyID = cs.companyID
WHERE cs.alias = 'foo'
SQL;

$pdo = new \PDO('mysql:host=127.0.0.1;dbname=dummy', 'root', '123456');

$statement = $pdo->query($sql, \PDO::FETCH_ASSOC);

\print_r($statement->fetchAll());

echo PHP_EOL;

The results will be

$ php scratch.php 
Array
(
    [0] => Array
        (
            [companyID] => 1
            [alias] => foo
        )

)

As you can see the alias column gets overriden.

After reading @michaloravec response, I see I totally missed the point.

If you want to get a customer with your relation consider eager loading it:

https://laravel.com/docs/8.x/eloquent-relationships#eager-loading

Something like this:

$records = Model::with(['contract.customers'])->get();

That way you will get the related contract and customers on your resultset.

I am really sorry but this is all so new and hard to grasp. I have read and tried but I cannot get it to work.

Here is my model:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Customers extends Model
{
    use HasFactory;

    protected $guarded = [];

    public function  user() {

        return  $this->belongsTo(User::class);
    }

    public function contracts() {

        return $this->hasMany(Contracts::class);
    }
    
}

Here is the method in the Controller:

public function contracts(Customers $customer) {

        return view('contracts.index', ['contracts' =>  $customer->contracts]);
    }

The Route:

Route::get('/customers/{customer}/contracts', [CustomersController::class, 'contracts']);

This gets me all my contracts for a certain customer. Along with these contracts, I need the customer's info. They are connected by foreign keys Contracts/customer_id is associated with Customers/id.

public function contracts(Customers $customer)
{
    $customer->load('contracts');

    return view('contracts.index', compact('customer'));
}

Then in the view you have $customer variable and contracts you can get with $customer->contracts.

Docs: https://laravel.com/docs/8.x/eloquent-relationships#lazy-eager-loading

By the way change model names to singular form so Customer and Contract.