Laravel eloquent query if(when condition )

Conditional Clauses

Sometimes you may want clauses to apply to a query only when something else is true. For instance you may only want to apply a where statement if a given input value is present on the incoming request. You may accomplish this using the when method:

https://laravel.com/docs/5.5/queries#conditional-clauses

$role = $request->input('role');

$users = DB::table('users')
                ->when($role, function ($query) use ($role) {
                    return $query->where('role_id', $role);
                })
                ->get();

The when method only executes the given Closure when the first parameter is true. If the first parameter is false, the Closure will not be executed.

You may pass another Closure as the third parameter to the when method. This Closure will execute if the first parameter evaluates as false. To illustrate how this feature may be used, we will use it to configure the default sorting of a query:

$sortBy = null;

$users = DB::table('users')
                ->when($sortBy, function ($query) use ($sortBy) {
                    return $query->orderBy($sortBy);
                }, function ($query) {
                    return $query->orderBy('name');
                })
                ->get();

***** This when(param1, function($query) use ($param2) {

}). Param1 can be a condition that evaluates to True or False as well, I.E

when(isset($param_1)....)

If $param1 is a value, remeber 0 evaluates to false