Basic Data Operations

this guide demonstrates how to manage parse objects on back4app using the flutter plugin for parse server you'll learn the basic crud operations create, read, update, and delete this tutorial uses a simple todo app to illustrate these operations back4app backend data storage revolves around the parseobject , which holds key value pairs of json compatible data the back4app data storage accommodates a wide range of common data types, including strings, numbers, booleans, datetime, geopoints, pointers, relations, as well as lists and objects essentially, it supports any data that can be encoded in json format, providing a flexible and robust solution for various data storage needs prerequisites to complete this tutorial, you will need flutter version 3 x x or later android studio https //developer android com/studio or vs code installed (with plugins dart and flutter) an app created on back4app note follow the new parse app tutorial to learn how to create a parse app on back4app an flutter app connected to back4app note follow the install parse sdk on flutter project to create an flutter project connected to back4app a device (or virtual device) running android or ios 1\ create object the savetodo function creates a new task with a title and a done status set to false here’s how it works initialize parse object setting its attributes create an instance of parseobject for your class (e g , 'todo') use the set method to define the key value pairs save the object call the save method to store the object in the database future\<void> savetodo(string title) async { final todo = parseobject('todo') set('title', title) set('done', false); await todo save(); } 2\ read object the gettodo function queries the database and returns a list of tasks here’s how it works initialize the query create an instance of querybuilder for your class execute the query use the query method to retrieve data handle the response check if the query was successful and process the results future\<list\<parseobject>> gettodo() async { querybuilder\<parseobject> querytodo = querybuilder\<parseobject>(parseobject('todo')); final parseresponse apiresponse = await querytodo query(); if (apiresponse success && apiresponse results != null) { return apiresponse results as list\<parseobject>; } else { return \[]; } } update the listview\ builder function to extract and display parse object values // get parse object values final vartodo = snapshot data!\[index]; final vartitle = vartodo get\<string>('title')!; final vardone = vartodo get\<bool>('done')!; 3\ update object the updatetodo function updates the status of an existing task here’s how it works initialize the parse object and set attributes create an instance of parseobject and set its objectid use the set method to update key value pairs save the object call the save method to update the object in the database future\<void> updatetodo(string id, bool done) async { var todo = parseobject('todo') objectid = id set('done', done); await todo save(); } 4\ delete object the deletetodo function removes an existing task from the database here’s how it works initialize the parse object create an instance of parseobject and set its objectid delete the object call the delete method to remove the object from the database future\<void> deletetodo(string id) async { var todo = parseobject('todo') objectid = id; await todo delete(); } full example code here’s the complete code for a simple todo app integrated with back4app backend import 'package\ flutter/material dart'; import 'package\ parse server sdk flutter/parse server sdk flutter dart'; void main() async { widgetsflutterbinding ensureinitialized(); const keyapplicationid = 'your app id here'; const keyclientkey = 'your client key here'; const keyparseserverurl = 'https //parseapi back4app com'; await parse() initialize(keyapplicationid, keyparseserverurl, clientkey keyclientkey, autosendsessionid true); runapp(const materialapp(home todoapp())); } class todoapp extends statefulwidget { const todoapp({super key}); @override // ignore library private types in public api todoappstate createstate() => todoappstate(); } class todoappstate extends state\<todoapp> { list\<parseobject> tasks = \[]; texteditingcontroller taskcontroller = texteditingcontroller(); @override void initstate() { super initstate(); gettodo(); } @override widget build(buildcontext context) { return materialapp( debugshowcheckedmodebanner false, theme themedata( primarycolor colors white, hintcolor colors black, scaffoldbackgroundcolor colors white, appbartheme appbartheme(backgroundcolor color fromargb(255, 68, 122, 246))), home scaffold( appbar appbar( title const text('todo list'), ), body container( decoration boxdecoration( border border all(color colors black), ), child column( children \[ const sizedbox(height 20), buildtaskinput(), const sizedbox(height 20), expanded(child buildtasklist()), ], ), ), ), ); } widget buildtaskinput() { return padding( padding const edgeinsets symmetric(horizontal 20), child row( children \[ expanded( child textfield( controller taskcontroller, decoration inputdecoration( hinttext 'enter tasks', filled true, fillcolor colors grey\[200], border outlineinputborder( borderradius borderradius circular(8), borderside borderside none, ), ), ), ), const sizedbox(width 10), elevatedbutton( onpressed addtodo, style buttonstyle( foregroundcolor materialstateproperty all\<color>(colors black)), child const text('add'), ), ], ), ); } widget buildtasklist() { return listview\ builder( itemcount tasks length, itembuilder (context, index) { final vartodo = tasks\[index]; final vartitle = vartodo get\<string>('title') ?? ''; bool done = vartodo get\<bool>('done') ?? false; return listtile( title row( children \[ checkbox( value done, onchanged (newvalue) { updatetodo(index, newvalue!); }, ), expanded(child text(vartitle)), ], ), trailing iconbutton( icon const icon(icons delete), onpressed () { deletetodo(index, vartodo objectid!); }, ), ); }, ); } future\<void> addtodo() async { string task = taskcontroller text trim(); if (task isnotempty) { var todo = parseobject('todo') set('title', task) set('done', false); var response = await todo save(); if (response success) { setstate(() { tasks add(todo); }); taskcontroller clear(); } else { // handle error } } } future\<void> updatetodo(int index, bool done) async { final vartodo = tasks\[index]; final string id = vartodo objectid tostring(); var todo = parseobject('todo') objectid = id set('done', done); var response = await todo save(); if (response success) { setstate(() { tasks\[index] = todo; }); } else { // handle error } } future\<void> gettodo() async { var querybuilder = querybuilder\<parseobject>(parseobject('todo')); var apiresponse = await querybuilder query(); if (apiresponse success && apiresponse results != null) { setstate(() { tasks = apiresponse results as list\<parseobject>; }); } else { // handle error } } future\<void> deletetodo(int index, string id) async { var todo = parseobject('todo') objectid = id; var response = await todo delete(); if (response success) { setstate(() { tasks removeat(index); }); } else { // handle error } } } your app should look like this conclusion you have now implemented the basic crud operations in a flutter app using parse on back4app this tutorial demonstrated how to add, retrieve, update, and delete tasks in a todo app