notekeeper

Asynchronus Programming in Flutter

Since Dart is Single threaded so is , Flutter. Normally Android Aplication are Multithreaded, because they use multiple threads to run different process parallaly. But in Flutter all the parallel processing is performed on single thread, using Asynchronus programming with the help of Three APIs.

1. future
2. async
3. await

SQLite DataBase in Flutter

SQLite an in-process library SQL database Engine, that implements Self-contained -- requires less support from exteranl libraries and platform independent. Serverless--reads and writes database files on the disks.locally on the device Zero configuration -- no installation and setup required, Transactional-- transaction either completes or not..no in between

Plugin -- SQFLite Plugin --let us access SQLite database in both iOS and Android ..Must include dependency in pubsec.yaml file. This Plugin only deals with Map object,i.e., only saves Map objects to SQLite database. Therefore convert data into map obeject. Similarly to fetch data from database, first convert it from map object to required data type to use it in the application.

Our Requirement for SQLite Database Implementation

1. Model Class -To represent Note Object 2.Database helper -to perform CRUD operations.(Inset , update, etc) 3.Connect database to UI.

Add Dependecies

sqflite:any
path-provider:any // commonly used location on file system intl: 0.16.1 //This package provides internationalization and localization facilities, including message translation, plurals and genders, date/number formatting and parsing, and bidirectional text.

Model Class Implementation

add models package create dart file for "note" object.. which will be stored in note.db database just like any SQL table columns(ID,Title,Description,Priority,Date).

1.create class and initialize all the properties(attributes) 2.define setter and getter function for all the properties 3.define object conversion(Note<->Map) fucntions for map object to store and getch from database. NOTE OBJECT TO MAP OBJECT.

Database Helper Class

Creating Singleton Object define INSERT,FETCH,DELETE,UPDATE functions. CRUD operations

Sigleton Object->instance which will be initialized only once,throughout the lifecycle of our app. We use stastic key word.

1.define and intialize all the database attributes,along with database table. 2.create and intialize the database 3.create getter for database -- returns old DB if exist or create new and return 4.define CRUD operations SQL queries can be passed using any of the following two methods, 1) rawQuery,rawInsert,rawDelete,rawUpdate-- ('COMPLETE SQL QUERY')
OR 2) query, insert , delete , update -- ('JUST PASS THE ARGUMENTS ')

5. define a function to count total notes in our database.

Connecting database operations to Home Screen UI

Import all the necessary package in both the screens file.

Define priority functions to change color and icons of note according to priority.Add these functions to Note widgets

Define delete and updateListview function using dbHelper functions

Define a function in dbHelper to convert Map List to Note List to fetch the notes to show it on home screen. Modify the navigationTodetail function add a note obejct as parameter. change all the function's signature associated with it.

Edit Screen functionality

Set priority using radio buttons. Using text controllers update both the text fields Insert or delete the Note,according to user response. Always move back to previous screen after performing an operation.