Laravel/Lumen - defining a relationship with parameters - laravel

Question

Consider a model Employee and a model Project
The employees table has a property type that can be assigned the following values "1", "2", "3", etc.
Project hasMany Employees
public function programmers() {
return $this->hasMany( 'App\Employee' )
->where( 'type', '1' );
} // hasMany programmers
public function testers() {
return $this->hasMany( 'App\Employee' )
->where( 'type', '2' );
} // hasMany testers
public function managers() {
return $this->hasMany( 'App\Employee' )
->where( 'type', '3' );
} // hasMany managers
Instead of these relationships, I would want to have only one:
public function employees( $type_id ) {
return $this->hasMany( 'App\Employee' )
->where( 'type', $type_id );
} // hasMany employees
It would work like this:
$app->get( '/employee', function() {
$project = App\Employee::find( 1 );
return $project->employees( "1" );
} );
However, I am getting the following exception:
ErrorException in Response.php line 402:
Object of class Illuminate\Database\Eloquent\Relations\HasMany could not be converted to string

Answer 1

Look at the contents of the error message:
ErrorException in Response.php line 402:
Object of class Illuminate\Database\Eloquent\Relations\HasMany could not be converted to string
The error is occurring in the Response class. The reason this error is coming up is because you're returning a relationship in your route definition rather than a response:
$app->get( '/employee', function() {
$project = App\Employee::find( 1 );
return $project->employees( "1" );
} );
A Relationship object cannot be converted to a string, and therefore the Response class doesn't know what to do with it.
If you want to examine the result of your relationship query in the browser, you'll need to return a valid response.
Try changing your route to something like this:
$app->get( '/employee', function() {
$project = App\Employee::find( 1 );
return response()->json($project->employees( "1" )->get());
} );
This will output the results of your query to JSON. Notice also the use of get(). This makes sure the relationship query is actually executed.