The response content must be a string or object implementing __toString(), "boolean" given after move to PSQL
Stefan Izdrail
Founder & Senior Architect · 2026-06-29
Title: Debugging "The Response content must be a string or object implementing __toString(), 'boolean' given" Error When Moving from MySQL to PSQL in Laravel Apps
Body:
As you move your Laravel application from MySQL to PostgreSQL (PSQL), you may encounter the error `The Response content must be a string or object implementing __toString(), "boolean"`. This can be particularly confusing if you're returning an API response that includes both JSON objects and boolean values, which are common in APIs for delivering data and boolean conditions to clients.
To understand this issue better, let's analyze the code snippet provided:
```php
public function id($id){
$promotion = Promotion::find($id); // This is a call to the model
dd($promotion) // Debugger command used for displaying output of $promotion variable
}
```
In this code, you're fetching a promotion with a given ID: `$promotion = Promotion::find($id);`. The debugging tool `dd()` is being called to display the object returned by this query. The error occurs when the response content isn't a string or an object implementing __toString(), but rather contains boolean values.
To resolve the issue, there are several possible solutions:
1. Check the type of returned value from `find()` and handle it accordingly. In this case, since the object returned is an instance of Eloquent Model with boolean values, you can convert them to strings using methods `getBooleanFlagsAsStrings()` or `toJson()` before sending them as a response:
```php
$promotion = Promotion::find($id);
$json_response = $promotion->toJson(JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_PARTIAL_OUTPUT_CONTROL); // This will ensure boolean values are properly parsed as strings
return response()->json($json_response, 200); // Send the response to the client as a JSON array with boolean values converted to strings
```
2. If your Laravel application has multiple APIs and the error is only occurring for one specific API endpoint, you can use conditional statements to handle each case differently:
```php
public function id($id){
$promotion = Promotion::find($id);
if (true) { // Check if the boolean value needs conversion in this particular case
$json_response = $promotion->toJson(JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_PARTIAL_OUTPUT_CONTROL);
} else {
dd($promotion) // Display the object as is, since no conversion needed
}
}
```
3. If all responses in your application need this kind of handling for boolean values, you can create a custom method on your Model classes to handle the conversion:
```php
// App\Models\Model.php
public function jsonSerialize() { // This method is called automatically when an object is converted to JSON
return array_merge(parent::jsonSerialize(), ['booleanFlagsAsStrings' => $this->getBooleanFlagsAsStrings()]);
}
// In your model, use this new property when converting the object to a JSON response:
$json_response = $promotion->toJson(JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_PARTIAL_OUTPUT_CONTROL); // This will handle all boolean values for you automatically
```
By applying one of these solutions, you can successfully move your Laravel application from MySQL to PSQL while ensuring that your API responses are correctly formatted and the debugger works as expected.