Laravel Illegal operator and value combination Exception on with() with belongsTo() relation

Title: Understanding Laravel Illegal Operator and Value Combination Exception with belongsTo() Relation and Ajax Calls Body: You have followed the best practices in Laravel to establish a belongsTo() relationship between your 'Call' model and the 'Campaign' model. This association ensures that each call belongs to a campaign if specific conditions are met, providing a flexible way to store and retrieve data efficiently. Although there is no issue with this association when directly accessing the view, you want to apply the same logic in conjunction with Ajax calls. To achieve this objective, you attempted to use the with() method on your Call model while selecting all the calls ordered by their 'call_start' field in descending order and then returning them if an Ajax request was detected. However, you encountered an exception "InvalidArgumentException in Builder.php line 464: Illegal operator and value combination." The error is caused primarily due to how Laravel processes queries with the 'where()' function. In your previous code example, where the campaign relationship was not involved, the query processed as follows: 1. Select any calls that belong to a campaign with a gsm_number match 2. Filter those calls based on call_start either being equal to or greater than '0000-00-00 00:00:00' for the start date of the Campaign and end date of the Call, respectively. In Ajax queries, you need to adapt the query logic to take into account any potential filtering that may affect the campaign data. One way to achieve this is by separating the 'where()' conditions in your query:

$calls = Call::with('campaign')->orderBy('call_start','DESC');
if($request->ajax()){
  if ($filteredCampaignData) { // Add filtering logic for campaigns here, e.g., $filteredCampaignData = Campagin::where(...)
    $calls->whereHas('campaign', function($query) use($filteredCampaignData) {
      return $query->whereIn('gsm_number', $filteredCampaignData['gsm_numbers']); // This will filter calls based on campaign gsm_numbers
    });
  }
  else if ($callFiltering) {
    $calls->where(function($query) use($callFiltering) {
      return $query->where('start_date', '<=', $callFiltering['start']) ... // Add any other filtering conditions based on your requirements here
        ->orWhere('end_date', '=', '0000-00-00 00:00:00');
    });
  }
  $matches = array_merge($calls->get(), $yourAdditionalData); // You can add additional data here if needed
  return response()->json($matches);
} else {
  return view('calls')->with('calls',$calls);
}

In this code snippet, we separate your query into two distinct parts: retrieving calls with the campaign relationship and filtering campaign data. This allows for a more flexible and error-free approach to dealing with Ajax calls while preserving the core functionality of your application. You can apply similar logic when dealing with other related models or complex relationships in Laravel. Remember that it is always essential to test your queries across different scenarios (e.g., filtering only campaigns, filtering calls, or no filters) to ensure they operate correctly and efficiently. For more information on how to handle various conditions and exceptions in Laravel queries, refer to the official documentation or seek guidance from experienced developers.