I am accessing HTML files directly from an AWS S3 bucket through Node.js and using Puppeteer to create PDFs. However, the generated PDFs are showing unusual characters instead of the correct content.
I have taken several steps to try to fix this issue:
- Content Types: I tested various content types for the HTML files in S3 to make sure they are processed properly.
- Puppeteer Settings: I modified several Puppeteer settings, including page configurations and viewport dimensions, to check their effect on the PDF result.
Unfortunately, these actions haven’t led to any improvement in resolving the issue. Any help or tips for debugging this problem would be greatly appreciated.
const puppeteer = require('puppeteer');
const AWS = require('aws-sdk');
const s3 = new AWS.S3();
exports.handler = async (event) => {
const srcBucket = event.Records[0].s3.bucket.name;
const srcKey = event.Records[0].s3.object.key;
const destBucket = 'my-pdf-reports';
const destKey = srcKey.replace('.html', '.pdf');
let browser;
try {
browser = await puppeteer.launch({ headless: true });
const page = await browser.newPage();
const objectData = await s3.getObject({ Bucket: srcBucket, Key: srcKey }).promise();
await page.setContent(objectData.Body.toString(), { waitUntil: 'networkidle0' });
const pdfBuffer = await page.pdf({ format: 'A4', printBackground: true });
await s3.putObject({ Bucket: destBucket, Key: destKey, Body: pdfBuffer, ContentType: 'application/pdf' }).promise();
console.log(`PDF saved at: s3://${destBucket}/${destKey}`);
} catch (error) {
console.error('Error during PDF creation:', error);
} finally {
if (browser) await browser.close();
}
};
Weird characters in your PDFs could often be due to encoding issues or missing fonts. Here’s a quick rundown to fix it:
- **Ensure UTF-8 Encoding:**
Double-check your HTML has <meta charset="UTF-8"> in the <head> section.
- **Read HTML with UTF-8:**
Use objectData.Body.toString('utf8') to ensure Puppeteer reads the content correctly.
- **Embed Fonts Directly:**
Try using web-safe fonts or embed custom fonts in Puppeteer to avoid missing symbols.
Here's how you can adjust the code:
const htmlContent = objectData.Body.toString('utf8');
await page.setContent(htmlContent, { waitUntil: 'networkidle0' });
const pdfBuffer = await page.pdf({ format: 'A4', printBackground: true, preferCSSPageSize: true });
If the problems continue, check your S3 settings or see if any external resources in your HTML disrupt rendering.
The issue of unusual characters appearing in your PDF could be linked to character encoding problems. Here are a few suggestions to help troubleshoot and potentially resolve the issue:
-
Character Encoding: Ensure that the encoding of your HTML content is explicitly set to UTF-8. You can do this by checking the <meta charset="UTF-8"> tag is present in the <head> of your HTML.
-
Fetching HTML Content: When fetching the HTML from S3, confirm that the content is being interpreted correctly. Instead of using objectData.Body.toString() directly, try specifying the expected encoding. For instance, you can use:
const htmlContent = objectData.Body.toString('utf8');
This ensures that the HTML content is read as UTF-8.
-
Font Embedding: Consider embedding fonts in your PDF. Sometimes, fonts used in HTML are not available during PDF rendering, causing unexpected symbols. You can do so by utilizing web-safe fonts or embedding custom fonts in Puppeteer if necessary.
-
Media Handling: If your HTML content includes any media (e.g., images, stylesheets) hosted externally or that require web requests, ensure they are correctly referenced and accessible during Puppeteer’s rendering process.
Here’s a brief code snippet illustrating some of these tips:
await page.setContent(htmlContent, {
waitUntil: 'networkidle0',
});
const pdfBuffer = await page.pdf({
format: 'A4',
printBackground: true,
preferCSSPageSize: true,
});
By taking these steps, you should be able to mitigate the presence of any unusual characters in your PDFs. If issues persist, check the S3 object encoding settings or inspect whether specific content (e.g., scripts or styles) affects the rendering.
Unusual characters in PDFs created with Puppeteer often stem from encoding and font issues. Here’s how you can efficiently tackle this:
- Ensure UTF-8 Encoding:
Include <meta charset="UTF-8"> in your HTML's <head> to ensure proper character interpretation.
- Read HTML as UTF-8:
Use objectData.Body.toString('utf8') to accurately read HTML content from S3, ensuring Puppeteer processes it correctly.
- Embed Fonts:
Utilize web-safe fonts or ensure your custom fonts are available during PDF generation to prevent substitution issues.
- Configuring Puppeteer:
Optimize Puppeteer settings by setting preferCSSPageSize to true for better page size handling. Ensure all required resources are loaded.
Integrate these tips into your existing code:
const htmlContent = objectData.Body.toString('utf8');
await page.setContent(htmlContent, { waitUntil: 'networkidle0' });
const pdfBuffer = await page.pdf({ format: 'A4', printBackground: true, preferCSSPageSize: true });
By following these steps, you've optimized the PDF creation process and reduced the likelihood of encountering unusual characters. If issues persist, verify your HTML content and S3 configurations.
Unusual characters in your PDF output can indeed be troubling, but let's approach it from another angle, focusing on both the content and the external environment:
- Encoding and HTML Headers:
It's crucial that your HTML content consistently specifies UTF-8 encoding as already mentioned. Also, ensure any scripts or stylesheets referenced within your HTML are UTF-8 encoded to prevent misinterpretations.
- Data Retrieval from S3:
Double-check that the data retrieved from S3 is not undergoing any unintentional transformations or corruptions. Consider logging the size and a small snippet of your HTML to ensure it arrives as expected.
- External Resources:
If your HTML relies on external resources (like stylesheets or fonts hosted outside), verify their accessibility. Use local paths or embedded resources to rule out network availability issues.
- Font Rendering:
You might have discrepancies with font rendering if fonts are not available or are substituted inadequately by Puppeteer. As an alternative, try hosting custom fonts those your HTML cannot live without within your environment or opt for universally supported fonts.
- Error Logging:
Enhance error messages by logging the stack trace more comprehensively. This helps in identifying if the source of the problem could be an edge case you haven't considered.
Incorporate these adjustments into your setup:
const htmlContent = objectData.Body.toString('utf8');
await page.setContent(htmlContent, { waitUntil: 'networkidle0' });
const pdfBuffer = await page.pdf({ format: 'A4', printBackground: true, preferCSSPageSize: true });
// Additionally, scrutinize and validate HTML content here
By methodically examining both internal code and external dependencies, you can often pinpoint and resolve these unexpected character issues. Validate whether resources are properly loaded during Puppeteer's execution, and if the problem persists, further investigate the S3 configurations or metadata involved.