Eloquent join with where clause - laravel

Question

I have problems to build a relationship with eloquent.
I have two models created, Spielplan and Verein. In model Spielplan I have the fields Team_ID and Spiel_ID. In model Verein I have the field V_ID and Name. Now I need to join this two tables about Team_ID = V_ID.
This is my model
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Spielplan extends Model
{
protected $table = 'Spielplan';
public function vereinFunction(){
return $this->hasOne('App\Verein', 'V_ID');
}
}
And this is a function in my web route where I want to get Spiel_ID and Name.
Route::get('test', function(){
$spieleT = App\Spielplan::where('Spiel_ID', '=', 30)->get();
foreach($spieleT as $da){
echo $da->Spiel_ID;
echo $da->vereinFunction->Name;
}
});
The first echo works and I get back Spiel_ID but the second echo gives back ErrorException Trying to get property of non-object.
What is wrong with my code?

Answer 1

Try editing this line:
$spieleT = App\Spielplan::with('vereInFunction')->where('Spiel_ID', '=', 30)->get();.
The with() allows you to fetch the association at the time you use get(). After using get(), you're working with a collection, and can't query the database again.

Answer 2

Try specifying the model primary key as a third argument, because if not, Laravel will assume it is named id, which is not the case.
Allow me to suggest you something: I used to name the tables and fields like you do (in the days I use Codeigniter) but since I started using Laravel around three years ago, I follow Laravel convention (which is recommended, but not imposed). I now name the tables in lowercase, (snakecase) plural, table fields also snakecasm lowercase. Models singular, camelcase similar corresponding table, relation function names as related model, being singular if relation is to one, plural if to many, etc. The advantage of this is among other reflected in model relationship declaration, which is a lot simpler and easier to define.
For instance (only as demonstration of stated above),
tables (with relation one to many:
managers (primarykey: id, name, ......)
technicians (primary key: id, foreingkey: manager_id (related table name in singular plus underscore plus id), name, .....)
models:
Manager:
/* relationships */
public function technicians () // see name as related table, plural due to as many relationship)
{
return $this->hasMany(Technician::class); // as naming convention has followed, you don't need to specify any extra parameters;
}
Techician:
/* relationship */
public function manager() // named as related table, singular due to to one relationship
{
$this->belongsToOne(Manager::class); // again, as naming convention has followed, you don't need to specify any extra parameters;
}
Therefore you can do this:
$manager::find(1);
echo $manager->technicians->first()->name,
or
foreach ($manager->technicians as $technician) {
echo $technician->name;
}
as well as:
$technician->manager->name;
Remember, a proper model relationship definition will save a lot of headache along the way, like the one you have
Hope this help in anyway