feat: added post endpoint

README.md

@@ -3,4 +3,4 @@ NodeJS Logging stream example
 
 ## Usage
 1. Run the server with `npm run start`
-2. Try sending a POST request to `http://localhost:20019/logging` (Replace *logging* with any filename).
+2. Try sending a POST request to `http://localhost:8080/logging` (Replace *logging* with any filename).

src/api/post.ts

@@ -0,0 +1,35 @@
+// :: Using streams to avoid loading the entire file in order to write to it.
+// :: This will allow scalability, and prevent large memory reads
+
+import { createReadStream, createWriteStream } from 'fs'
+// :: This library helps wrapping a generator into a readable stream to be piped
+// :: https://www.npmjs.com/package/async-stream-generator
+const streamify = require("async-stream-generator");
+
+// :: Use a generator to wait to the read stream to finish, adding chunks to later parse them
+async function* addChunk(chunks: any, body: any) {
+    let data = ''
+    for await (const chunk of chunks) {
+        data += chunk.toString()
+    }
+    // :: Small validation in case the file is empty
+    const modifiedChunk = data.length ? JSON.parse(data) : []
+    // :: Add data as requested
+    modifiedChunk.push([(new Date).getTime(), body])
+    yield JSON.stringify(modifiedChunk)
+}
+
+// :: Having this functionality separated, allows the code to be more readable and maintanable
+export const saveData = (request: any, response: any) => {
+    // :: The name of the file to create
+    const file = `${request.params.target}.log`
+    // :: The read stream is created with a+ to create log files in case they do not exist
+    const readStream = createReadStream(file, { flags: 'a+' })
+    // :: Overriden default write flag, to avoid the file to be truncated
+    const writeStream = createWriteStream(file, { flags: 'r+' })
+    // :: Pipe the streams
+    streamify(addChunk(readStream, request.body)).pipe(writeStream)
+
+    // :: Send the response as we are not waiting for the log to finish
+    response.status(200).send('Log updated')
+}

src/index.ts

@@ -0,0 +1,11 @@
+import express from 'express'
+import { saveData } from './api/post'
+
+const server = express()
+server.use(express.json());
+
+// :: Endpoint that parses requests
+server.post('/:target', saveData)
+
+const port = process.env.PORT || 8080
+server.listen(port, () => console.info(`Server started at http://localhost:${port}`))