جلسه دیتابیس sqlite

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E/flutter (23963): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: Null check operator used on a null value
E/flutter (23963): #0 MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:86)
E/flutter (23963): #1 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
E/flutter (23963): #2 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
E/flutter (23963): #3 invokeMethod (package:sqflite/src/sqflite_impl.dart:17:13)
E/flutter (23963): #4 SqfliteDatabaseFactoryImpl.invokeMethod (package:sqflite/src/factory_impl.dart:82:7)
E/flutter (23963): #5 SqfliteDatabaseFactoryMixin.safeInvokeMethod. (package:sqflite_common/src/factory_mixin.dart:41:38)
E/flutter (23963): #6 wrapDatabaseException (package:sqflite/src/exception_impl.dart:7:32)
E/flutter (23963): #7 SqfliteDatabaseFactoryImpl.wrapDatabaseException (package:sqflite/src/factory_impl.dart:78:7)
E/flutter (23963): #8 SqfliteDatabaseFactoryMixin.safeInvokeMethod (package:sqflite_common/src/factory_mixin.dart:41:7)
E/flutter (23963): #9 SqfliteDatabaseFactoryMixin.getDatabasesPath (package:sqflite_common/src/factory_mixin.dart:152:26)
E/flutter (23963): #10 getDatabasesPath (package:sqflite/sqflite.dart:161:54)
E/flutter (23963): #11 MyDB.initDb (package:first_and_stu/database.dart:24:24)
E/flutter (23963): #12 MyDB.db (package:first_and_stu/database.dart:19:16)
E/flutter (23963): #13 MyDB.insert (package:first_and_stu/database.dart:35:26)
E/flutter (23963): #14 main (package:first_and_stu/main.dart:9:19)
E/flutter (23963): #15 _runMainZoned.. (dart:ui/hooks.dart:142:25)
E/flutter (23963): #16 _rootRun (dart:async/zone.dart:1354:13)
E/flutter (23963): #17 _CustomZone.run (dart:async/zone.dart:1258:19)
E/flutter (23963): #18 _runZoned (dart:async/zone.dart:1789:10)
E/flutter (23963): #19 runZonedGuarded (dart:async/zone.dart:1777:12)
E/flutter (23963): #20 _runMainZoned. (dart:ui/hooks.dart:138:5)
E/flutter (23963): #21 _delayEntrypointInvocation. (dart:isolate-patch/isolate_patch.dart:283:19)
E/flutter (23963): #22 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
E/flutter (23963):
E/flutter (23963): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: type ‘Future’ is not a subtype of type ‘Database?’
E/flutter (23963): #0 MyDB.db (package:first_and_stu/database.dart:19:5)
E/flutter (23963): #1 MyDB.insert (package:first_and_stu/database.dart:35:26)
E/flutter (23963): #2 main (package:first_and_stu/main.dart:9:19)
E/flutter (23963): #3 _runMainZoned.. (dart:ui/hooks.dart:142:25)
E/flutter (23963): #4 _rootRun (dart:async/zone.dart:1354:13)
E/flutter (23963): #5 _CustomZone.run (dart:async/zone.dart:1258:19)
E/flutter (23963): #6 _runZoned (dart:async/zone.dart:1789:10)
E/flutter (23963): #7 runZonedGuarded (dart:async/zone.dart:1777:12)
E/flutter (23963): #8 _runMainZoned. (dart:ui/hooks.dart:138:5)
E/flutter (23963): #9 _delayEntrypointInvocation. (dart:isolate-patch/isolate_patch.dart:283:19)
E/flutter (23963): #10 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
E/flutter (23963):