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Dan McGhan
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Added streaming files example
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14 files changed

+1264
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‎javascript/files-up-and-down/hr_app_streaming/config/database.js

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module.exports = {
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hrPool: {
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user: process.env.HR_USER,
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password: process.env.HR_PASSWORD,
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connectString: process.env.HR_CONNECTIONSTRING,
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poolMin: 10,
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poolMax: 10,
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poolIncrement: 0
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}
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};

‎javascript/files-up-and-down/hr_app_streaming/config/web-server.js

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module.exports = {
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port: process.env.HTTP_PORT || 3000
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};

‎javascript/files-up-and-down/hr_app_streaming/controllers/employees.js

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const employees = require('../db_apis/employees.js');
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async function get(req, res, next) {
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try {
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const context = {};
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context.id = parseInt(req.params.id, 10);
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context.skip = parseInt(req.query.skip, 10);
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context.limit = parseInt(req.query.limit, 10);
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context.sort = req.query.sort;
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context.department_id = parseInt(req.query.department_id, 10);
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context.manager_id = parseInt(req.query.manager_id, 10);
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const rows = await employees.find(context);
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if (req.params.id) {
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if (rows.length === 1) {
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res.status(200).json(rows[0]);
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} else {
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res.status(404).end();
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}
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} else {
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res.status(200).json(rows);
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.get = get;
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function getEmployeeFromRec(req) {
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const employee = {
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first_name: req.body.first_name,
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last_name: req.body.last_name,
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email: req.body.email,
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phone_number: req.body.phone_number,
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hire_date: req.body.hire_date,
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job_id: req.body.job_id,
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salary: req.body.salary,
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commission_pct: req.body.commission_pct,
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manager_id: req.body.manager_id,
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department_id: req.body.department_id
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};
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return employee;
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}
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async function post(req, res, next) {
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try {
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let employee = getEmployeeFromRec(req);
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employee = await employees.create(employee);
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res.status(201).json(employee);
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} catch (err) {
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next(err);
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}
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}
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module.exports.post = post;
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async function put(req, res, next) {
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try {
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let employee = getEmployeeFromRec(req);
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employee.employee_id = parseInt(req.params.id, 10);
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employee = await employees.update(employee);
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if (employee !== null) {
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res.status(200).json(employee);
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} else {
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res.status(404).end();
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.put = put;
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async function del(req, res, next) {
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try {
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const id = parseInt(req.params.id, 10);
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const success = await employees.delete(id);
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if (success) {
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res.status(204).end();
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} else {
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res.status(404).end();
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.delete = del;
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‎javascript/files-up-and-down/hr_app_streaming/controllers/file_details.js

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const fileDetails = require('../db_apis/file_details.js');
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async function get(req, res, next) {
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try {
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const context = {};
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context.id = parseInt(req.params.id, 10);
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const rows = await fileDetails.find(context);
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if (req.params.id) {
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if (rows.length === 1) {
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res.status(200).json(rows[0]);
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} else {
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res.status(404).end();
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}
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} else {
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res.status(200).json(rows);
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.get = get;

‎javascript/files-up-and-down/hr_app_streaming/controllers/files.js

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const files = require('../db_apis/files.js');
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const { Transform } = require('stream');
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// Create a new transform stream class that can validate files.
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class FileValidator extends Transform {
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constructor(options) {
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super(options.streamOptions);
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this.maxFileSize = options.maxFileSize;
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this.totalBytesInBuffer = 0;
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}
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_transform (chunk, encoding, callback) {
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this.totalBytesInBuffer += chunk.length;
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// Look to see if the file size is too large.
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if (this.totalBytesInBuffer > this.maxFileSize) {
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const err = new Error(`The file size exceeded the limit of ${this.maxFileSize} bytes`);
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err.code = 'MAXFILESIZEEXCEEDED';
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callback(err);
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return;
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}
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this.push(chunk);
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callback(null);
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}
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_flush (done) {
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done();
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}
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}
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async function post(req, res, next) {
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try {
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// Get a new instance of the transform stream class.
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const fileValidator = new FileValidator({
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maxFileSize: 1024 * 1024 * 5000 // 50 MB
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});
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let contentType = req.headers['content-type'] || 'application/octet';
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let fileName = req.headers['x-file-name'];
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if (fileName === '') {
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res.status(400).json({error: 'The file name must be passed in the via x-file-name header'});
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return;
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}
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// Pipe the request stream into the transform stream.
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req.pipe(fileValidator);
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// Could happen if the client cancels the upload. Forward upstream as an error.
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req.on('aborted', function() {
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fileValidator.emit('error', new Error('Upload aborted.'));
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});
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try {
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const fileId = await files.create(fileName, contentType, fileValidator);
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res.status(201).json({fileId: fileId});
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} catch (err) {
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console.error(err);
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res.header('Connection', 'close');
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if (err.code === 'MAXFILESIZEEXCEEDED') {
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res.status(413).json({error: err.message});
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} else {
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res.status(500).json({error: 'Oops, something broke!'});
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}
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req.connection.destroy();
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.post = post;
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async function get(req, res, next) {
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try {
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let aborted = false;
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let row;
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const id = parseInt(req.params.id, 10);
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if (isNaN(id)) {
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res.status(400).json({error: 'Missing or invalid file id'});
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return;
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}
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// Could happen if the client cancels the download. Forward upstream as an error.
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req.on('aborted', function() {
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aborted = true;
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if (row) {
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row.blob_data.emit('error', new Error('Download aborted.'));
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}
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});
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row = await files.get(id);
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// It's possible the aborted event happened before the readable stream was
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// obtained. Reemit the event to handle the error.
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if (aborted) {
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row.blob_data.emit('aborted');
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}
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if (row) {
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res.status(200);
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res.set({
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'Cache-Control': 'no-cache',
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'Content-Type': row.content_type,
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'Content-Length': row.file_length,
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'Content-Disposition': 'attachment; filename=' + row.file_name
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});
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row.blob_data.pipe(res);
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} else {
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res.status(404).end();
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.get = get;
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async function del(req, res, next) {
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try {
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const id = parseInt(req.params.id, 10);
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if (isNaN(id)) {
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res.status(400).json({error: 'Missing or invalid file id'});
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return;
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}
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const success = await files.delete(id);
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if (success) {
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res.status(204).end();
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} else {
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res.status(404).end();
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}
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} catch (err) {
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next(err);
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}
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}
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module.exports.delete = del;

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