How to understand entities, save, hasChanged

Read https://codeigniter.com/user_guide/model...attributes

Thank you Kenjis. I previously read that. The below code works but I dont understnad why.

In line 3 below, I used find() and it returns a $category entity. Is line 3 required in order for line 5 to work properly? How does hadChanged() understand it changed?

PHP Code:

1    public function category_update($category_id)
2   {
3        $category = $this->CategoryModel->find($category_id);
4        if ($this->request->getMethod() === 'post') {
5            $category->fill($this->request->getPost());
6            if (!$category->hasChanged()){
7                return redirect()->back()->with('info', 'Nothing to update');
8                
9            }
10            if ($this->CategoryModel->save($category)) {
11                return redirect()->to('/admin/post/categories')
12                                 ->with('info', 'Success - category name was updated');
13            } else {
14                return redirect()->back()
15                                 ->with('errors', $this->CategoryModel->errors())
16                                 ->with('warning', 'Invalid Data')
17                                 ->withInput();
18            }
19        } else {
20            $this->data['category'] = $this->CategoryModel->find($category_id);
21            return view('/Admin/Category/category_update', $this->data    );
22        }
23    } 


---

going back to my original problem, I am readying a geojson from file. I put it into an associative array. On the first run of the script, everything imports to the db as expected. If I changed something in the geojson text file, I want to just save the updated parts. Unfortunately, the code says every record hasChanged. I have changed around my code to try to understand what is ocurring but I cannot see why also see as hasChanged.

PHP Code:

public function update_aa_winter_sports_points_from_file(){
    
        $file = file_get_contents(WRITEPATH.'upload_fs_data/aa_winter_sports_points.geojson');
        $aa_winter_sports_points = json_decode($file);  // The json_decode() function is used to decode or convert a JSON object to a PHP object.
        // to count the number of ski resorts
        $i = 0;
    
        echo 'Numnber of ski resorts: '.count($aa_winter_sports_points->features);  echo '</br>';
        
        foreach ($aa_winter_sports_points->features as $aa_winter_sports_point ){
        
            echo '----------------------------------</br>';
            echo 'File row number '.$i.'</br>';
            $data = array($aa_winter_sports_point->properties);

            // Convert stdClass object to associative array in php
            // https://stackoverflow.com/questions/34428702/convert-stdclass-object-to-associative-array-in-php
            $new_fill = json_decode(json_encode($data[0]), TRUE);
       
            // find() will return an entity $existing_data.  Works also in findAll();
            $existing_fill = $this->OsmSkiResortModel->find($new_fill['id']);
          
            // (1/4) if not in db but in file, create db entry
            if(!$existing_fill){
                $OsmSkiResort = new \App\Entities\OsmSkiResortEntity();
                $this->OsmSkiResortModel->save($OsmSkiResort->fill($new_fill));
                echo "Added New Record</br>";
            };
            
            // (3/4) if in db and in file but info in file has changed, update db
            if($existing_fill){
               
                $OsmSkiResort = new \App\Entities\OsmSkiResortEntity();
                
                $OsmSkiResort->fill($new_fill);
                if ($OsmSkiResort->hasChanged()){
                    
                    echo '<pre>';
                    echo "Data has changed</br>";
                    echo "This is what CI says has changed:<br>";
            print_r($OsmSkiResort->toRawArray(true));
                    
             echo "This is what is in the database<br>";
             $OsmSkiResort = $this->OsmSkiResortModel->find($new_fill['id']);
             print_r($OsmSkiResort);
                 echo '</pre>';
            echo '<br><br>';
                }
                
    }
                
       
            $i++;
            
        }
        
    } 


And here is the output:

Numnber of ski resorts: 223
----------------------------------
File row number 0
Data has changed
This is what CI says has changed:
Array
(
[landuse] => winter_sports
[name] => チセヌプリスキー場
[name:en] => Chisennupri
[name:ja] => 蘭越町チセヌプリスキー場
[piste:type] => playground
[sport] => skiing
[type] => multipolygon
[id] => relation/8385428
)
This is what is in the database
App\Entities\OsmSkiResortEntity Object
(
[snip]