The response content must be a string or object implementing __toString(), "boolean" given after move to PSQL

Question

As soon as I move my Laravel App from MySQL to PSQL, I kept getting this error:

The Response content must be a string or object implementing __toString(), "boolean" given.

I have an API that is supposed to return my promotion

http://localhost:8888/api/promotion/1

public function id($id){
    $promotion = Promotion::find($id);
    dd($promotion); //I got something here
    return $promotion;
}

It used it to return my promotion, but now it returns an error.

---

dd($promotion);

I got 

Promotion {#410 ▼
  #table: "promotions"
  #connection: null
  #primaryKey: "id"
  #perPage: 15
  +incrementing: true
  +timestamps: true
  #attributes: array:16 [▼
    "id" => 1
    "cpe_mac" => "000D6721A5EE"
    "name" => "qwrqwer"
    "type" => "img_path"
    "status" => "Active"
    "heading_text" => "qwerq"
    "body_text" => "werqwerqw"
    "img" => stream resource @244 ▶}
    "img_path" => "/images/promotion/1/promotion.png"
    "video_url" => ""
    "video_path" => ""
    "account_id" => 1001
    "img_url" => ""
    "footer_text" => "qwerqwerre"
    "created_at" => "2016-08-04 10:53:57"
    "updated_at" => "2016-08-04 10:53:59"
  ]
  #original: array:16 [▶]
  #relations: []
  #hidden: []
  #visible: []
  #appends: []
  #fillable: []
  #guarded: array:1 [▶]
  #dates: []
  #dateFormat: null
  #casts: []
  #touches: []
  #observables: []
  #with: []
  #morphClass: null
  +exists: true
  +wasRecentlyCreated: false
}

---

#Content

Answer 1

TL;DR

Just returning response()->json($promotion) won't solve the issue in this question. $promotion is an Eloquent object, which Laravel will automatically json_encode for the response. The json encoding is failing because of the img property, which is a PHP stream resource, and cannot be encoded.

Details

Whatever you return from your controller, Laravel is going to attempt to convert to a string. When you return an object, the object's __toString() magic method will be invoked to make the conversion.

Therefore, when you just return $promotion from your controller action, Laravel is going to call __toString() on it to convert it to a string to display.

On the Model, __toString() calls toJson(), which returns the result of json_encode. Therefore, json_encode is returning false, meaning it is running into an error.

Your dd shows that your img attribute is a stream resource. json_encode cannot encode a resource, so this is probably causing the failure. You should add your img attribute to the $hidden property to remove it from the json_encode.

class Promotion extends Model
{
    protected $hidden = ['img'];

    // rest of class
}