[OCR] Node Express server 예제

const express = require('express');
const bodyParser = require('body-parser');

const app = express();
const router = express.Router();

router.post('/request', (req, res) => {
	const file = _.get(req, ['file']);
	const filePath = _.get(file, 'path');
	const page = _.get(req.body, ['page']) || 0;
	const originalName = _.get(file, 'originalname');
	const mimeType = _.get(file, 'mimetype');
	const extension = path.extname(originalName).split('.')[1] || mimeType.split('/')[1];
	const filePathWithExt = filePath + '.' + extension;

	fs.renameSync(filePath, filePathWithExt);
	try {
		const ocrResult = await requestOCR(filePathWithExt, page);
		const imagePath = await downloadImage(ocrResult.result.masked_image);
		res.end(JSON.stringify({ result: ocrResult.result, imagePath }));
	} catch (error) {
		res.status(error.status).send(error.message);
	}
}

function requestOCR('/request', (imgPath, page) => {
    const apiKey = OCR_API_KEY; // 발급 받은 OCR API Key를 입력합니다.
    const options =  {
		url: `${OCR_SDK_URL}/ocr`,
		formData: {
			api_key: OCR_API_KEY,
			image: fs.createReadStream(imgPath),
			page_index: page,
			...OCROption
		}
    };
	
	request.post(options).on('response', response => {
        const statusCode = _.get(response, 'statusCode');
        const statusMessage = _.get(response, 'statusMessage');
        if (statusCode === 200) {
            console.log('OCR 성공');
            let body = [];
            response.on('error', (err) => {
                throw err;
            }).on('data', (chunk) => {
                body.push(chunk);
            }).on('end', () => {
                // 전송 완료
                const data = JSON.parse(Buffer.concat(body).toString());
                // 클라이언트에게 응답
                return res.status(statusCode).json(data);
            });
        } else {
            console.log('OCR 실패', statusCode);
            const error = new Error(statusMessage);
            error.status = statusCode;
            // 클라이언트에게 오류 응답
            return res.status(statusCode).json({ error: statusMessage });
        }
    });
}

function downloadImage(fileName) {
    return new Promise((resolve, reject) => {
        const options = {
            url: `${OCR_SDK_URL}/out/${fileName}`,
            formData: {
                api_key: OCR_API_KEY,
            }
        };

        const imagePath = path.resolve(WORK_DIR, fileName);
        request.post(options).on('response', response => {
            const statusCode = _.get(response, 'statusCode');
            const statusMessage = _.get(response, 'statusMessage');
            if (statusCode === 200) {
                console.log('OCR image download 성공');

                let imageData = Buffer.from([]);
                response.on('data', (chunk) => {
                    imageData = Buffer.concat([imageData, chunk]);
                }).on('end', () => {
                    const relativeImagePath = '/' + path.relative(ROOT_DIR, imagePath).replace(/\\/g, '/');
                    fs.writeFileSync(imagePath, imageData); // 이미지 저장
                    resolve(relativeImagePath);
                });
            } else {
                console.log('OCR image download 실패', statusCode);
                const error = new Error(statusMessage);
                error.status = statusCode;
                reject(error);
            }
        });
    });
}

app.use(bodyParser.json());
app.use('/', router);
app.listen(8080);