Build: Build HTTP-Triggered Function

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◆ Before you start

Prerequisites

Azure Functions Core ToolsRequired
npm i -g azure-functions-core-tools@4
Get it ↗
Node.js 20+Required
func init + func new
Azure CLIOptional
For deploying to Azure

⚡

Step 1 of 2

Build HTTP-Triggered Function

Create an Azure Function with HTTP trigger using the v4 programming model.

Tasks

func init myfunction --typescript --model V4

func new --name processOrder --template "HTTP trigger"

Implement handler with input validation

func start to run locally

🎯 What You'll Learn

▸Understand Azure Functions v4 programming model
▸Handle HTTP request/response with TypeScript types
▸Run and test locally with Core Tools

Code

TypeScriptsrc/functions/processOrder.ts
1 import { app, HttpRequest, HttpResponseInit, InvocationContext } from '@azure/functions';
2  
3 app.http('processOrder', {
4   methods: ['POST'],
5   authLevel: 'function',
6   handler: async (req: HttpRequest, ctx: InvocationContext): Promise<HttpResponseInit> => {
7     const body = await req.json() as { orderId: string; amount: number };
8  
9     if (!body.orderId || body.amount <= 0) {
10       return { status: 400, jsonBody: { error: 'Invalid request' } };
11     }
12  
13     ctx.log(`Processing order: ${body.orderId}`);
14     // Business logic here
15     return {
16       status: 200,
17       jsonBody: { transactionId: `txn-${Date.now()}`, orderId: body.orderId }
18     };
19   },
20 });

💡 Pro Tips

▸v4 model uses app.http() instead of function.json files
▸authLevel: anonymous for local dev, function for production

Expected Output

curl POST localhost:7071/api/processOrder returns JSON response

Discussion

1 import { app, HttpRequest, HttpResponseInit, InvocationContext } from '@azure/functions'; 2 3 app.http('processOrder', { 4 methods: ['POST'], 5 authLevel: 'function', 6 handler: async (req: HttpRequest, ctx: InvocationContext): Promise<HttpResponseInit> => { 7 const body = await req.json() as { orderId: string; amount: number }; 8 9 if (!body.orderId || body.amount <= 0) { 10 return { status: 400, jsonBody: { error: 'Invalid request' } }; 11 } 12 13 ctx.log(`Processing order: ${body.orderId}`); 14 // Business logic here 15 return { 16 status: 200, 17 jsonBody: { transactionId: `txn-${Date.now()}`, orderId: body.orderId } 18 }; 19 }, 20 });

1	import { app, HttpRequest, HttpResponseInit, InvocationContext } from '@azure/functions';
2
3	app.http('processOrder', {
4	methods: ['POST'],
5	authLevel: 'function',
6	handler: async (req: HttpRequest, ctx: InvocationContext): Promise<HttpResponseInit> => {
7	const body = await req.json() as { orderId: string; amount: number };
8
9	if (!body.orderId \|\| body.amount <= 0) {
10	return { status: 400, jsonBody: { error: 'Invalid request' } };
11	}
12
13	ctx.log(`Processing order: ${body.orderId}`);
14	// Business logic here
15	return {
16	status: 200,
17	jsonBody: { transactionId: `txn-${Date.now()}`, orderId: body.orderId }
18	};
19	},
20	});