DataBase Query : return all results if field is null

You were assigning $query when null, but you should've assigned $car_list which is the original query you're building on.

   public function list(Request $request){
        
        $carGov = $request->get('carGov');
        $carName = $request->get('carName');
        $carModel = $request->get('carModel');
        $car_list = Car::select('cargov', 'carname', 'carmodel');
        $car_list = is_null($carModel) ? $car_list : $car_list->wherecarmodel($carModel);
        $car_list = is_null($carName) ? $car_list : $car_list->wherecarname($carName);
        $result = $car_list->orderBy('updated_at','DESC')->paginate(10);
        return response()->json($result,200);
    }

but you should've assigned $car_list as you mentioned but its produce the same result ( empty list ) when car name, model is not provided. I'm testing with postman and when I don't provide carModel and return $carModel instead of car_list the result is ""

   public function list(Request $request){
        
    $query = Car::select('cargov', 'carname', 'carmodel');

    if($request->filled('carGov') {
        $query->where('cargov', $request->carGov);
    }

    if($request->filled('carName') {
        $query->where('carname', $request->carName);
    }

    if($request->filled('carModel') {
        $query->where('carmodel', $request->carModel)
    }

        $result = $query->orderBy('updated_at','DESC')->paginate(10);

        return response()->json($result,200);
    }

Easier to follow

Is this your exact code? My original posting had a typo

@mriyadh If you prefer chaining

$result = Car::select('cargov', 'carname', 'carmodel')
    ->when($request->filled('carGov'), function($query) use ($request) {
        return $query->where('cargov', $request->carGov);
    })
    ->when($request->filled('carName'), function($query) use ($request) {
        return $query->where('carname', $request->carName);
    })
    ->when($request->filled('carModel'), function($query) use ($request) {
        return $query->where('carmodel', $request->carModel);
    })
    ->orderBy('updated_at','DESC')->paginate(10);

return response()->json($result, 200);

@Snapey How can i change below line to select all columns ? or i have to add them all

$query = Car::select('cargov', 'carname', 'carmodel');

I think

$query = Car::select('*');

or

$query = Car::newQuery();

@Snapey Thanks man,

Its

$query = Car::select('*');

@Snapey Sorry for re posting but I'm facing a strange behavior with this code,

public function list(Request $request){
       
   $query = Car::select('cargov', 'carname', 'carmodel');

   if($request->filled('carGov') {
       $query->where('cargov', $request->carGov);
   }

   if($request->filled('carName') {
       $query->where('carname', $request->carName);
   }

   if($request->filled('carModel') {
       $query->where('carmodel', $request->carModel)
   }

       $result = $query->orderBy('updated_at','DESC')->paginate(10);

       return response()->json($result,200);
   }

As you can see I'm paging the result of my query ( 10 / Page ), the first page results matches the query successfully but starting from Page2 and so on the results will not match the query (exactly select all with out any conditions) ? any ideas why this is happening.

you have to add the query terms back to the pagination link.

@Snapey Again I'm sorry for not being so clear I agree with you for passing the query terms but let me explain more .

my request response is like below,

{
    "current_page": 1,
    "data": [
        {
            // array of my object
        }
    ],
    "first_page_url": "https://www.example.com/Search?page=1",
    "from": 1,
    "last_page": 3,
    "last_page_url": "https://www.example.com/Search?page=3",
    "next_page_url": "https://www.example.com/Search?page=2",
    "path": "https://www.example.com/Search",
    "per_page": 10,
    "prev_page_url": null,
    "to": 10,
    "total": 27
}

The response is already provide the next page url which I use directly to fetch the next page and so on, When i use it with simple query like,

public function list(){
        
        $car_list = Car::where([['cargage', '>', 10000]])->orderBy('updated_at','DESC')->paginate(10);
        return response()->json($car_list,200);
    }

There is no need to pass the query terms with each page but it's loosing the terms only here

public function list(Request $request){
       
   $query = Car::select('cargov', 'carname', 'carmodel');

   if($request->filled('carGov') {
       $query->where('cargov', $request->carGov);
   }

   if($request->filled('carName') {
       $query->where('carname', $request->carName);
   }

   if($request->filled('carModel') {
       $query->where('carmodel', $request->carModel)
   }

       $result = $query->orderBy('updated_at','DESC')->paginate(10);

       return response()->json($result,200);
   }

Yes, each page has no history of what went before.

So, your URL, instead of being

https://www.example.com/Search?page=2

it needs to be

https://www.example.com/Search?page=2&carModel=big&carName=fred

see https://www.example.com/Search?page=2

Look down to Appending To Pagination Links

You can do this in the controller before returning your json I think

You should look for request when directive.. it simplifies the query even further ithink