Why data variables are persisting the old values in Flutter app?

Question

I am so confused about the data persistence in my app. I am using google drive api to fetch a spreadsheet file(.xlsx) and then read and show the excel cell values in my app using an itemBuilder. The main problem is that when I edit some cells in my google spreadsheet on the browser and fetch the file(which is now updated) from the app, it does not show the new values. I noticed that my app takes some time to fetch file for the first time but after that it fetches immediately. I am going to show about how I am fetching file and updating it.

Initialization of variables:

//I am using excel dart package
late var excel;
late drive.DriveApi driveApi;
late Sheet sheet;

String fileId = "19jF3lOVW563LU6mEjqAjXVLNQ7poXY1Z"; //xlsx file id

Fetching of file from drive:

drive.Media? response = (await driveApi.files.get(fileId,downloadOptions: drive.DownloadOptions.fullMedia)) as drive.Media?;

List<int> dataStore = [];                                                 
response!.stream.listen((data) {                                          
  dataStore.insertAll(dataStore.length, data);                            
}, onDone: (){                                                            
  excel = Excel.decodeBytes(dataStore);            //excel variable declaration                       
  sheet = excel['Sheet1'];    
}, onError: (error) {                           
  Fluttertoast.showToast(msg: error.toString());
});                                                                                         

Showing values of excel using itemBuilder

Widgets----
............
............
............
............ 
itemCount: sheet.maxRows - 1,                           
itemBuilder: (context, index) {                         
  var cell = sheet.cell(CellIndex.indexByColumnRow(     //taking values from excel sheets
      rowIndex: index + 1, columnIndex: itr));          
  String val = cell.value.toString().toLowerCase();     
  if (cell.value == null ||                             
      (val != 'present' && val != 'absent')) {          
    cell.value = 'absent';                              
    cell.cellStyle = absent;                            
  }                                                     
                                                        
  return ListTile(                                      
    subtitle: Text(cell.value.toString()),              
    title: Row(                                         
      children: <Widget>[                               
        const Icon(Icons.person),                       
        Expanded(                                       
          child: Text(sheet.rows[index + 1][0]!.value   
              .toString()),  

............
............
............
............  
Widgets----                         

Updating the excel file to google drive:

//First I am creating a unique pathName, then creating a file and saving the new excel values
//to the newly created file 

final String path = (await getApplicationSupportDirectory()).path;      
final String fileName = path + cryptoRandom() + '/$fileId.xlsx';                                          
File newFile = File(fileName);                                          
                                                                        
var driveFile = new drive.File();                                       
driveFile.name = basename(newFile.path);   
//Saving excel to newFile                             
File(join(newFile.path))                                                
  ..createSync(recursive: true)                                         
  ..writeAsBytesSync(excel.encode()!);                                  

//Updating the newFile                                                                     
await driveApi.files.update(driveFile, fileId,                          
    uploadMedia: drive.Media(newFile.openRead(), newFile.lengthSync()));

//Deleting the created file
newFile.deleteSync(recursive: true);                                    

Why the old values persist in my app, even when I am creating new file everytime and deleting them also. Why this is happening, I sthis because of some cache data or what ? Thanks

Answer 1

you can set as null or any default value. when first run page vars will be default one. and another place you can get your main datas.