This documentation provides details for the RESTful API created using Node.js and Express. The API includes endpoints for creating, reading, updating, and deleting items.
\nCreating a web server with node and express. The in client side of android with Kotlin used retrofit for HTTP connection with server.
\nGithub Repository : https://github.com/abtaaahi/Retrofit-Web-Server-Kotlin-Node.js
\nhttp://localhost:1113
dependencies {\n implementation(\"com.squareup.retrofit2:retrofit:2.9.0\")\n implementation(\"com.squareup.retrofit2:converter-gson:2.9.0\")\n implementation(\"com.squareup.okhttp3:logging-interceptor:4.9.0\")\n}\n\nCreate a ApiService for RESTful API:
import retrofit2.Call\nimport retrofit2.http.*\ninterface ApiService {\n @GET(\"get\")\n fun getItems(): Call<List<Item>>\n @GET(\"get/{id}\")\n fun getItem(@Path(\"id\") id: Int): Call<Item>\n @POST(\"post\")\n fun createItem(@Body item: Item): Call<Item>\n @PUT(\"update/{id}\")\n fun updateItem(@Path(\"id\") id: Int, @Body item: Item): Call<Item>\n @DELETE(\"delete/{id}\")\n fun deleteItem(@Path(\"id\") id: Int): Call<Void>\n}\n\nCreate a data class Item :
data class Item (\n val id: Int = 0,\n val name: String,\n val course: String\n)\n\nInitialize Retrofit in a singleton
\nimport retrofit2.Retrofit\nimport retrofit2.converter.gson.GsonConverterFactory\nimport okhttp3.OkHttpClient\nimport okhttp3.logging.HttpLoggingInterceptor\nobject RetrofitInstance {\n private const val BASE_URL = \"http://192.168.1.13:1113/\"\n private val loggingInterceptor = HttpLoggingInterceptor().apply {\n setLevel(HttpLoggingInterceptor.Level.BODY)\n }\n private val client = OkHttpClient.Builder()\n .addInterceptor(loggingInterceptor)\n .build()\n val retrofit: Retrofit by lazy {\n Retrofit.Builder()\n .baseUrl(BASE_URL)\n .client(client)\n .addConverterFactory(GsonConverterFactory.create())\n .build()\n }\n val apiService: ApiService by lazy {\n retrofit.create(ApiService::class.java)\n }\n}\n\nMainActivity.kt
import android.os.Bundle\nimport androidx.appcompat.app.AppCompatActivity\nimport retrofit2.Call\nimport retrofit2.Callback\nimport retrofit2.Response\nimport android.widget.Button\nimport android.widget.EditText\nimport android.widget.TextView\nclass MainActivity : AppCompatActivity() {\n private val apiService = RetrofitInstance.apiService\n override fun onCreate(savedInstanceState: Bundle?) {\n super.onCreate(savedInstanceState)\n setContentView(R.layout.activity_main)\n btnGet.setOnClickListener { getItem() }\n btnPost.setOnClickListener { createItem() }\n btnPut.setOnClickListener { updateItem() }\n btnDelete.setOnClickListener { deleteItem() }\n }\n private fun getItem() {\n val idText = etId.text.toString()\n if (idText.isEmpty()) {\n apiService.getItems().enqueue(object : Callback<List<Item>> {\n override fun onResponse(call: Call<List<Item>>, response: Response<List<Item>>) {\n if (response.isSuccessful) {\n val items = response.body() ?: emptyList()\n tvResult.text = if (items.isNotEmpty()) {\n \"${items.joinToString(separator = \"\\n\") { \"${it.id}: ${it.name}, ${it.course}\" }}\"\n } else {\n \"No items found.\"\n }\n } else {\n tvResult.text = \"GET ALL Error: ${response.code()}\"\n }\n }\n override fun onFailure(call: Call<List<Item>>, t: Throwable) {\n tvResult.text = \"GET ALL Failure: ${t.message}\"\n }\n })\n } else {\n val id = idText.toIntOrNull()\n if (id != null) {\n apiService.getItem(id).enqueue(object : Callback<Item> {\n override fun onResponse(call: Call<Item>, response: Response<Item>) {\n if (response.isSuccessful) {\n tvResult.text = \"${response.body()?.let { \"${it.id}: ${it.name}, ${it.course}\" }}\"\n } else {\n tvResult.text = \"GET Error: ${response.code()}\"\n }\n }\n override fun onFailure(call: Call<Item>, t: Throwable) {\n tvResult.text = \"GET Failure: ${t.message}\"\n }\n })\n } else {\n tvResult.text = \"Invalid ID. Please enter a valid numeric ID.\"\n }\n }\n }\n private fun createItem() {\n val id = etId.text.toString().toIntOrNull() ?: 0\n val name = etName.text.toString()\n val course = etDescription.text.toString()\n val newItem = Item(id = id, name = name, course = course)\n apiService.createItem(newItem).enqueue(object : Callback<Item> {\n override fun onResponse(call: Call<Item>, response: Response<Item>) {\n if (response.isSuccessful) {\n tvResult.text = \"POST Success: ${response.body()}\"\n } else {\n tvResult.text = \"POST Error: ${response.code()}\"\n }\n }\n override fun onFailure(call: Call<Item>, t: Throwable) {\n tvResult.text = \"POST Failure: ${t.message}\"\n }\n })\n }\n private fun updateItem() {\n val id = etId.text.toString().toIntOrNull()\n if (id != null) {\n val name = etName.text.toString()\n val course = etDescription.text.toString()\n val updatedItem = Item(id = id, name = name, course = course)\n apiService.updateItem(id, updatedItem).enqueue(object : Callback<Item> {\n override fun onResponse(call: Call<Item>, response: Response<Item>) {\n if (response.isSuccessful) {\n tvResult.text = \"PUT Success: ${response.body()}\"\n } else {\n tvResult.text = \"PUT Error: ${response.code()}\"\n }\n }\n override fun onFailure(call: Call<Item>, t: Throwable) {\n tvResult.text = \"PUT Failure: ${t.message}\"\n }\n })\n } else {\n tvResult.text = \"Please enter a valid ID\"\n }\n }\n private fun deleteItem() {\n val id = etId.text.toString().toIntOrNull()\n if (id != null) {\n apiService.deleteItem(id).enqueue(object : Callback<Void> {\n override fun onResponse(call: Call<Void>, response: Response<Void>) {\n if (response.isSuccessful) {\n tvResult.text = \"DELETE Success: ${response.code()}\"\n } else {\n tvResult.text = \"DELETE Error: ${response.code()}\"\n }\n }\n override fun onFailure(call: Call<Void>, t: Throwable) {\n tvResult.text = \"DELETE Failure: ${t.message}\"\n }\n })\n } else {\n tvResult.text = \"Please enter a valid ID\"\n }\n }\n}\n\nnetwork-security-config.xml in res/xml:
<network-security-config>\n<base-config cleartextTrafficPermitted=\"true\">\n <trust-anchors>\n <certificates src=\"system\" />\n </trust-anchors>\n</base-config>\n</network-security-config>\n\nAndroidManifest.xml
<manifest>\n <uses-permission android:name=\"android.permission.INTERNET\"></uses-permission>\n android:networkSecurityConfig=\"@xml/network_security_config\"\n android:usesCleartextTraffic=\"true\"\n </application>\n</manifest>\n\nServer Setup:
\nmkdir node-web-server
cd node-web-server
npm init -y
npm install express
Server.js :
const express = require('express')\nconst app = express()\nconst port = 1113\napp.use(express.json())\nlet data = [\n { id: 1, name: 'Alex', course: 'Computer Science'},\n { id: 2, name: 'John', course: 'Electrical'},\n { id: 3, name: 'Charlie', course: 'Civil'},\n { id: 4, name: 'JohnWick', course: 'Mathematics' },\n { id: 5, name: 'Jane', course: 'Physics' },\n { id: 6, name: 'Smith', course: 'Chemistry' }\n]\n//Read all items\napp.get('/get', (req, res) => {\n res.json(data)\n})\n//Read specific item\napp.get('/get/:id', (req, res) => {\n const id = parseInt(req.params.id)\n const item = data.find( i => i.id === id)\n if(item){\n res.json(item)\n } else{\n res.status(404).send('Item Not Fund')\n }\n})\n//Create a new item\napp.post('/post', (req, res) => {\n const newItem = { id: data.length + 1, ...req.body}\n data.push(newItem)\n res.status(201).json(newItem)\n})\n//Update an item\napp.put('/update/:id', (req, res) => {\n const id = parseInt(req.params.id);\n const index = data.findIndex(i => i.id === id);\n if (index !== -1) {\n data[index] = { id, ...req.body };\n res.json(data[index]);\n } else {\n res.status(404).send('Item not found');\n }\n});\n// Delete an item\napp.delete('/delete/:id', (req, res) => {\n const id = parseInt(req.params.id);\n const index = data.findIndex(i => i.id === id);\n if (index !== -1) {\n const deletedItem = data.splice(index, 1);\n res.json(deletedItem[0]);\n res.send(`Item deleted`);\n } else {\n res.status(404).send('Item not found');\n }\n});\napp.get('/', (req, res) => {\n res.send(`Server running successfully`);\n});\napp.listen(port, () => {\n console.log(`Server running at http://localhost:${port}/`)\n})\n\npackage.json:
{\n \"name\": \"web-server\",\n \"version\": \"1.0.0\",\n \"main\": \"index.js\",\n \"scripts\": {\n \"test\": \"echo \\\"Error: no test specified\\\" && exit 1\"\n },\n \"keywords\": [],\n \"author\": \"\",\n \"license\": \"ISC\",\n \"description\": \"\",\n \"dependencies\": {\n \"express\": \"^4.19.2\"\n }\n}\n\nnode server.js