How to Create a CRUD Application with Kotlin?

overview in this walkthrough, you'll discover how to develop a simple crud (create, read, update, delete) application using kotlin we will utilize back4app as our backend service, which simplifies data management this guide illustrates the essential components of a crud system, including setting up a back4app project, designing a flexible data schema, and executing crud operations with a kotlin application we begin by configuring a back4app project named basic crud app kotlin that offers a scalable environment you will create data models either manually or with the assistance of back4app's ai agent next, you will leverage the back4app admin interface—a user friendly drag and drop tool—to manage your data effortlessly finally, you'll integrate your kotlin application with back4app using the parse java sdk (or api calls when required) while ensuring secure access management by the conclusion of this guide, you'll have built a production ready kotlin application capable of performing standard crud operations, complete with secure user authentication and efficient data handling major insights learn to construct a kotlin based crud application with a robust backend understand how to architect a scalable backend and connect it with a kotlin app master using back4app’s intuitive admin interface for streamlined crud tasks get acquainted with containerizing your kotlin app with docker for a smooth deployment process prerequisites before you begin, ensure that you have an active back4app account with a new project set up need guidance? see getting started with back4app https //www back4app com/docs/get started/new parse app a kotlin development environment utilize an ide such as intellij idea, and ensure you have kotlin and jdk 11 (or later) installed basic knowledge of kotlin, object oriented programming, and rest apis consult the kotlin documentation https //kotlinlang org/docs/home html if required step 1 – setting up the project creating a new back4app project log in to your back4app account click on the “new app” button from your dashboard input the project name basic crud app kotlin and complete the setup steps create new project after the project is created, it will appear on your dashboard, establishing the foundation for your backend configuration step 2 – crafting the data schema defining your data structures for this crud application, you'll define several collections within your back4app project below are sample classes and fields needed for standard crud operations 1\ items collection field data type purpose id objectid system generated unique identifier title string name of the item description string brief summary describing the item createdat date record creation timestamp updatedat date timestamp for the latest modification 2\ users collection field data type purpose id objectid automatically generated unique identifier username string unique username for each user email string distinct email address passwordhash string securely encrypted user password createdat date account creation timestamp updatedat date timestamp for account modifications you can manually add these collections and fields directly through the back4app dashboard create new class you can define fields by choosing the data type, naming the field, assigning default values, and marking required fields create column utilizing the back4app ai agent for schema generation the back4app ai agent simplifies schema setup by automatically generating the data model based on your description this efficient tool speeds up project initialization and ensures your schema supports all crud functionalities how to use the ai agent locate the ai agent log into your back4app dashboard and find the ai agent within the project settings detail your data schema provide a prompt outlining the required collections and their respective fields review and confirm inspect the proposed schema and approve it to implement the changes sample prompt create the following collections in my back4app project 1\) collection items \ fields \ id objectid (auto generated) \ title string \ description string \ createdat date (auto generated) \ updatedat date (auto updated) 2\) collection users \ fields \ id objectid (auto generated) \ username string (unique) \ email string (unique) \ passwordhash string \ createdat date (auto generated) \ updatedat date (auto updated) this ai powered feature minimizes manual configuration and optimizes your data model for crud operations step 3 – enabling the admin interface & managing crud operations overview of the admin interface the back4app admin interface is a no code solution that simplifies backend data management its intuitive design allows you to easily create, view, modify, and delete records activating the admin interface go to the “more” menu on your back4app dashboard select “admin interface” and then click on “enable admin interface ” configure your admin credentials by setting up an initial administrator account this also establishes roles (e g , b4aadminuser ) and system collections enable admin app once activated, sign in to the admin interface to manage your application data admin app dashboard using the admin interface for crud actions within this interface, you can insert records utilize the “add record” option in a collection (like items) to input new data inspect and modify records click on a record to review or update its fields remove records delete records that are no longer needed this user friendly interface streamlines data management significantly step 4 – connecting your kotlin application with back4app after configuring your backend, the next phase is to link your kotlin application with back4app it’s important to note that although we are using the parse java sdk, kotlin’s seamless interoperability with java allows you to integrate it without any issues option a utilizing the parse sdk for kotlin (via java) include the parse sdk dependency if you are using gradle, add the following to your build gradle kts dependencies { implementation("com parse\ parse sdk 1 18 0") } initialize parse in your kotlin application create a configuration file (e g , parseconfig kt ) // parseconfig kt import com parse parse object parseconfig { fun initialize() { parse initialize( parse configuration builder("your application id") clientkey("your kotlin key") server("https //parseapi back4app com") build() ) } } implement crud methods in kotlin for example, create a service to manage items // itemsservice kt import com parse parseexception import com parse parseobject import com parse parsequery object itemsservice { fun getitems() list\<parseobject>? { return try { parsequery getquery\<parseobject>("items") find() } catch (e parseexception) { println("error retrieving items ${'$'}{e message}") null } } fun createitem(title string, description string) { val item = parseobject("items") item put("title", title) item put("description", description) try { item save() println("item successfully created ") } catch (e parseexception) { println("failed to create item ${'$'}{e message}") } } fun updateitem(objectid string, newtitle string, newdescription string) { val query = parsequery getquery\<parseobject>("items") try { val item = query get(objectid) item put("title", newtitle) item put("description", newdescription) item save() println("item updated successfully ") } catch (e parseexception) { println("update failed ${'$'}{e message}") } } fun deleteitem(objectid string) { val query = parsequery getquery\<parseobject>("items") try { val item = query get(objectid) item delete() println("item deleted successfully ") } catch (e parseexception) { println("deletion error ${'$'}{e message}") } } } option b using rest or graphql apis if you prefer not to use the parse sdk, you can execute crud operations via rest calls for example, to retrieve items using rest import java io bufferedreader import java io inputstreamreader import java net httpurlconnection import java net url object restclient { fun fetchitems() { try { val url = url("https //parseapi back4app com/classes/items") val connection = url openconnection() as httpurlconnection connection requestmethod = "get" connection setrequestproperty("x parse application id", "your application id") connection setrequestproperty("x parse rest api key", "your rest api key") bufferedreader(inputstreamreader(connection inputstream)) use { reader > val response = reader readtext() println("response $response") } } catch (e exception) { println("error fetching items ${'$'}{e message}") } } } integrate these api calls within your kotlin classes as needed step 5 – enhancing security for your backend access control lists (acls) ensure your data remains secure by setting up acls on your objects for instance, to create an item that is accessible only by its owner import com parse parseacl import com parse parseexception import com parse parseobject import com parse parseuser fun createprivateitem(title string, description string, owner parseuser) { val item = parseobject("items") item put("title", title) item put("description", description) val acl = parseacl() acl setreadaccess(owner, true) acl setwriteaccess(owner, true) acl setpublicreadaccess(false) acl setpublicwriteaccess(false) item acl = acl try { item save() println("private item created successfully ") } catch (e parseexception) { println("error saving private item ${'$'}{e message}") } } class level permissions (clps) set up clps via the back4app dashboard to enforce default access policies, ensuring only authenticated users interact with sensitive collections step 6 – implementing user authentication configuring user management back4app leverages parse’s built in user collection for authentication in your kotlin app, you can handle user registration and login as follows import com parse parseexception import com parse parseuser object authservice { fun signup(username string, password string, email string) { val user = parseuser() user username = username user setpassword(password) user email = email try { user signup() println("registration successful!") } catch (e parseexception) { println("sign up error ${'$'}{e message}") } } fun login(username string, password string) { try { val user = parseuser login(username, password) println("logged in as ${'$'}{user username}") } catch (e parseexception) { println("login failed ${'$'}{e message}") } } } this structure can be extended for session management, password resets, and additional authentication mechanisms step 7 – conclusion and future enhancements congratulations! you have successfully built a kotlin based crud application integrated with back4app in this guide, you set up a project named basic crud app kotlin , defined data collections for items and users, and managed your data through the back4app admin interface furthermore, you connected your kotlin app via the parse sdk (or api calls) and implemented robust security practices next steps expand the application integrate additional features such as advanced search capabilities, detailed item views, or real time updates enhance backend functionality consider exploring cloud functions, third party api integrations, or advanced role based access controls deepen your expertise visit the back4app documentation https //www back4app com/docs for further guidance and advanced tutorials happy coding and best of luck with your kotlin crud application!