array_merge(): Argument #1 is not an array in laravel 5.5
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Debugging Database Merges in Laravel: Solving the `array_merge(): Argument #1 is not an array` Error
As a senior developer working with the Laravel ecosystem, we frequently encounter subtle yet frustrating errors when dealing with data manipulation, especially when combining results from Eloquent or the Query Builder. One common stumbling block developers face is the `array_merge(): Argument #1 is not an array` error. This often occurs when attempting to merge collections returned from database queries.
This post will dive deep into why this error happens in your specific scenario within a Laravel controller context and provide robust, idiomatic solutions using best practices.
## Understanding the Error in Context
You are facing this issue because of how methods like `->get()` return data in Laravel. When you execute `$isConnectedM = DB::table(...)->get();`, the result stored in `$isConnectedM` is not a simple PHP array; it is an instance of a Laravel **Collection**. While Collections behave similarly to arrays, some functions, or specific contexts where the data structure is being passed around, expect a native PHP array (`array`).
When you call `array_merge($isConnectedM, $isConnectedA)`, if one or both variables are not strictly interpreted as simple arrays (or collections that can be implicitly converted), PHP throws this error because it cannot perform the merge operation on non-array types. The root cause is usually ensuring that you extract the actual data from the Collection before merging.
## The Correct Solution: Extracting Data Safely
The fix involves explicitly converting the Laravel Collection objects into native PHP arrays using methods like `toArray()`. This ensures that `array_merge()` receives exactly what it expects: an array of values.
Here is how you can correct your controller method:
```php
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Response;
public function isConnectedMA()
{
$user_id = Auth::user()->id; // Use ->id instead of () for clarity
if (!empty($user_id)) {
// Fetch results, which are Laravel Collections
$isConnectedM = DB::table('user_mlc_mailchimp')->where('user_id', $user_id)->get();
$isConnectedA = DB::table('user_mlc_aweber')->where('user_id', $user_id)->get();
// *** THE FIX: Convert Collections to Arrays before merging ***
$mailchimpData = $isConnectedM->toArray();
$aweberData = $isConnectedA->toArray();
// Now merge the resulting native arrays
$MergeArray = array_merge($mailchimpData, $aweberData);
$resultArray = [
'status' => 1,
'message' => 'Template uploaded!',
'dataArray' => $MergeArray
];
return Response::json($resultArray, 200);
}
return Response::json(['status' => 0, 'message' => 'User not found'], 404);
}
```
By calling `->toArray()` on both results, you guarantee that `$mailchimpData` and `$aweberData` are standard PHP arrays, allowing `array_merge()` to execute successfully. This principle of transforming query results is fundamental when working with data in Laravel, as discussed in modern Laravel development practices.
## Best Practices: Leveraging Eloquent for Cleaner Data Handling
While the solution above fixes your immediate error, as a senior developer, I recommend looking for ways to structure your data retrieval more efficiently. Relying heavily on raw queries and manual merging can become cumbersome as applications scale.
Instead of fetching two separate records and merging them manually in the controller, consider if you can consolidate this logic into your database layer or use Eloquent relationships. If these tables are related, leveraging Eloquent's ability to handle relationships can simplify data retrieval significantly. For complex data interactions, mastering the principles outlined by the Laravel team can lead to cleaner, more maintainable code.
When dealing with relational data in Laravel, always strive to let the ORM handle the heavy lifting. If your goal is simply to retrieve related information, using Eloquent models and relationships often replaces the need for multiple, separate `DB::table()` calls followed by manual merging. This approach keeps your business logic focused on *what* data you need rather than *how* you fetch and stitch it together.
## Conclusion
The error `array_merge(): Argument #1 is not an array` is a classic symptom of mixing Laravel's Collection objects with native PHP functions expecting simple arrays. The solution is straightforward: explicitly convert your results using the `toArray()` method before attempting to merge them. By adopting this practice and focusing on leveraging Eloquent's power, you ensure your code is robust, readable, and adheres to modern Laravel standards.