Generating PDF files using Next.js
Tags: javascript, react, webdev, nextjs
Published: 2020-12-13 02:50:55

Next.js is a framework based on React, it´s quite popular lately, thanks to some awesome features, like SSR, SSG... some advantages over react vanilla. A common task to do in web development generates PDF´s maybe you need to show some extra info or generate reports of some dynamically generated data, there are many use cases for it, in one of my last projects, I´ve been figuring out how to do it directly from next.js, and today I´m gonna show you how you can do it too.

### Set Up
First, we need to initialize our project as we would do usually using next.js but adding the library to generate pdf's [jsPDF](https://github.com/MrRio/jsPDF)
```sh
mkdir next-pdf
cd ./next-pdf
yarn init --yes
yarn add react react-dom next js-pdf normalize.css
``` 
PS:normalize.css is optional but useful, makes browsers render all elements more consistently, is highly suggested.

Now edit your package.json and add the next lines
```json
...
"scripts": {
    "dev": "next",
    "start": "next start",
    "build": "next build",
  },
...
```
and run 
```bash
mkdir pages
```
pages/index.js
```javascript
const app =()=>(<h1>Hello world</h1>);

export default app;
```
with this setup is enough to start, but if you like to use typescript everywhere (like me haha) you can use the next lines to use it.

```bash
touch tsconfig.json
yarn add --dev @types/react @types/node @types/jspdf typescript

```
rename index.js to index.tsx and finally run 
```bash
yarn run dev
```

### Ok Let's go for it
we´ll create a folder named src where gonna be placed our component to generate PDF´s and our styles, and our scaffolding will looks like this
```bash
/src/
   /components/
       GeneratePDF.tsx
   /styles/
       styles.css
/pages/
   index.tsx
   _app.tsx
```
let's add global styles to our app, this is made on _app.tsx, importing styles.css and normalize.css:
```typescript
import * as React from "react";
import "normalize.css"
import "../src/styles/styles.css";

const MyApp = ({ Component, pageProps }) => {
  return (
    <Component {...pageProps} />
  );
};

export default MyApp;
```
our styles/styles.css
```css
.content{
    display:flex;
    align-items: center;
    flex-direction: column;
}

.main  > .content > p, h1{
    font-family: sans-serif;
   
}

.main > .content > p{
    font-size: 1.7em;
    text-align: justify;
    width:80%;
}

.main  button{
    display: block;
    cursor: pointer;
    background-color: crimson;
    color: white;
    font-size: 1.5em;
    font-family: sans-serif;
    width:8em;
    height: 3em;
    font-weight: 500;
    border-radius: 5px;
    border-color: transparent;
    margin:0 auto 0 auto;
}

.main .button-container{
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: row;
}
```
now our main components 
/src/components/GeneratePDF.tsx
```typescript
import React from "react";
import { jsPDF,HTMLOptionImage } from "jspdf";
import { toPng,toCanvas } from "html-to-image";
type props = {
  
  html?: React.MutableRefObject<HTMLDivElement>;

};

const GeneratePdf: React.FC<props> = ({ html }) => {
  const generatePdf = () => {
      const doc = new jsPDF();

      let split=doc.splitTextToSize(document.getElementById("text").innerText,200);
      let image = document.getElementById("image").getAttribute('src');
      doc.text(document.querySelector(".content > h1").innerHTML,75,5);
      doc.addImage(image,70,7,60,60);
      doc.text(split,5,75);
      doc.output("dataurlnewwindow");  

  };

  const generateImage=async ()=>{
    const image = await toPng(html.current,{quality:0.95});
    const doc = new jsPDF();
    
      doc.addImage(image,'JPEG',5,22,200,160);
      doc.save();

   
  }
  return (
    
    <div className="button-container">
        <button onClick={generateImage}>
        Get PDF using image
      </button>
      <button onClick={generatePdf}>
        Get PDF as text
      </button>
    </div>
    
  );
};

export default GeneratePdf;
```
explanation = we are creating 2 buttons to generate 2 pdf's with the same content but using 2 different approaches, *generateImage* will generate a image from our HTML , and we will put it inside a pdf , and *generatePdf* just create the pdf, taking the content from our Dom, all of them have their advantages and their disadvantages 

###Using Image:
#####Advantages
:white_check_mark: the result is exactly like on your page
:white_check_mark: easy to set up
#####Disadvantages
:x: Slow to generate 
:x: the pdf file weight is relatively high
:x: you can't copy and paste the content(if it matters for you)

###Using Content from the dom:
#####Advantages
:white_check_mark: Lightweight file size
:white_check_mark: Fast Generation
:white_check_mark: The text is selectable
#####Disadvantages
:x: is not so easy to set up everything in their own place

 let's continue with pages/index.tsx
```typescript
import * as React from "react";
import Image from "next/image";
import dynamic from "next/dynamic";
const GeneratePDF = dynamic(()=>import("./../src/components/GeneratePDF"),{ssr:false});
const app =()=>{
        const ref = React.useRef();

        return(<div className="main">
        <div className="content" ref={ref}>
        <h1>Hello PDF</h1>
        <img id="image" src="/images/image_header.jpg" width="300" height="200"/>
        <p id="text">
            Lorem ipsum dolor sit, amet consectetur adipisicing elit. Quisquam animi, molestiae quaerat assumenda neque culpa ab aliquam facilis eos nesciunt! Voluptatibus eligendi vero amet dolorem omnis provident beatae nihil earum!
            Lorem, ipsum dolor sit amet consectetur adipisicing elit. Ea, est. Magni animi fugit voluptates mollitia officia libero in. Voluptatibus nisi assumenda accusamus deserunt sunt quidem in, ab perspiciatis ad rem.
            Lorem ipsum dolor sit amet consectetur adipisicing elit. Nihil accusantium reprehenderit, quasi dolorum deserunt, nisi dolores quae officiis odio vel natus! Pariatur enim culpa velit consequatur sapiente natus dicta alias!
            Lorem ipsum dolor sit amet consectetur adipisicing elit. Consequatur, asperiores error laudantium corporis sunt earum incidunt expedita quo quidem delectus fugiat facilis quia impedit sit magni quibusdam ipsam reiciendis quaerat!
        </p>
        </div>
        <GeneratePDF html={ref}/>
        </div>);
}

export default app;
```
##Explanation
As we can see is another component made with react ... well not at all, as you can see we are using dynamic from next 
```typescript
import dynamic from "next/dynamic";
const GeneratePDF = dynamic(()=>import("./../src/components/GeneratePDF"),{ssr:false});
```
with this we are importing the component dynamically (basically only when is required) and we are deactivating the SSR (Server side rendering) because jsPDF requires to be initialized on the browser, otherwise, we would catch an error from it.

now you can generate PDF's from your next app, there are many approaches you can use for example auto generate [tables](https://github.com/simonbengtsson/jsPDF-AutoTable)

###Thanks for reading
If you have any question, or suggestion please, leave a comment below, and please follow me here and also on my [twitter](https://twitter.com/WonDErV14?s=09) take care :+1: