Creating PDF in PHP is a very useful skill that can help website developers generate various types of dynamic PDF files such as invoices, reports, certificates, etc. By using libraries and extensions in PHP, developers can easily convert data into PDF format and make it available on the website for users to download or print. This article will explain how to create PDF files in PHP using common libraries and extensions, as well as some practical tips and considerations.
library in php
We can create PDF in PHP using external library mpdf. We can retrieve data from the database, store them in a PDF, and then download the PDF. Using this library we can create PDF from html documents. HTML documents should be encoded in UTF-8. We can retrieve the data to be added to the PDF from the database in HTML format. We can use the library by downloading it from the project directory via the command composer require mpdf/mpd. This command will install the mpdf library in the project directory. A vendor file will be created and we need to use the require() function to include the file autoload.php located inside the vendor folder. We have to make sure that the directory where the library is installed should have write permission.
We will create an object from the Mpdf() constructor and use methods like WriteHTML() and output() to create the PDF. We can output PDF in different modes. We can specify the mode in the second parameter of the output() method. The different modes are represented by the D, I, F, and S options. Option D will force a download of the PDF after the script is run. After the script runs, option I will display the PDF in the browser. Also, option F will save the downloaded PDF in a folder relative to the PHP file. Finally, option F will output a pdf in the browser only if the output() method is assigned to a variable.
For example, we have a database named phprow which contains a table named Persons. Table Persons contains the following data.
<code> <code class="language-sql hljs" data-lang="sql"><span style="display:flex;"><span><span style="color:#666">+</span><span style="color:#408080;font-style:italic">----------+----------+-----------+ </span></span></span><span style="display:flex;"><span><span style="color:#666">|</span><span style="color:#bbb"> </span>PersonID<span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span>Name<span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span>Address<span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span></span></span><span style="display:flex;"><span><span style="color:#666">+</span><span style="color:#408080;font-style:italic">----------+----------+-----------+ </span></span></span><span style="display:flex;"><span><span style="color:#666">|</span><span style="color:#bbb"> </span><span style="color:#666">22</span><span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span>Harry<span style="color:#bbb"> </span>M<span style="color:#bbb"></span><span style="color:#666">|</span><span style="color:#bbb"> </span>England<span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span></span></span><span style="display:flex;"><span><span style="color:#666">|</span><span style="color:#bbb"> </span><span style="color:#666">32</span><span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span>Paul<span style="color:#bbb"> </span>P<span style="color:#bbb"> </span><span style="color:#666">|</span><span style="color:#bbb"> </span>France<span style="color:#bbb"></span><span style="color:#666">|</span><span style="color:#bbb"> </span></span></span><span style="display:flex;"><span><span style="color:#666">+</span><span style="color:#408080;font-style:italic">----------+----------+-----------+ </span></span></span></code></code>
First, include the vender/autoload.php file using the require() function. Then, create and establish a database connection, run a sql query to select data from the database, and create a table in the $html variable. Use the . operator to join the $html variable with the body of the table. Create a table with headers ID, Name, and Address. The table is then populated by retrieving the above data from the Persons table.
Sample code:
<code>
<code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">require</span>(<span style="color:#ba2121">'vendor/autoload.php'</span>);
</span></span><span style="display:flex;"><span><span style="color:#19177c">$con</span><span style="color:#666">=</span><strong class="keylink">Mysql</strong>i_connect(<span style="color:#ba2121">'localhost'</span>,<span style="color:#ba2121">'root'</span>,<span style="color:#ba2121">''</span>,<span style="color:#ba2121">'phprow'</span>);
</span></span><span style="display:flex;"><span><span style="color:#19177c">$res</span><span style="color:#666">=</span><strong class="keylink">mysql</strong>i_query(<span style="color:#19177c">$con</span>,<span style="color:#ba2121">"select * from Persons"</span>);
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">if</span>(mysqli_num_rows(<span style="color:#19177c">$res</span>)<span style="color:#666">></span><span style="color:#666">0</span>){
</span></span><span style="display:flex;"><span><span style="color:#19177c">$html</span><span style="color:#666">=</span><span style="color:#ba2121">'<table>'</span>;
</span></span><span style="display:flex;"><span><span style="color:#19177c">$html</span><span style="color:#666">.=</span><span style="color:#ba2121">'<tr><td>ID</td><td>Name</td><td>Address</td>'</span>;
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">while</span>(<span style="color:#19177c">$row</span><span style="color:#666">=</span>mysqli_fetch_assoc(<span style="color:#19177c">$res</span>)){
</span></span><span style="display:flex;"><span><span style="color:#19177c">$html</span><span style="color:#666">.=</span><span style="color:#ba2121">'<tr><td>'</span><span style="color:#666">.</span><span style="color:#19177c">$row</span>[<span style="color:#ba2121">'PersonID'</span>]<span style="color:#666">.</span><span style="color:#ba2121">'</td><td>'</span><span style="color:#666">.</span><span style="color:#19177c">$row</span>[<span style="color:#ba2121">'Name'</span>]<span style="color:#666">.</span><span style="color:#ba2121">'</td><td>'</span><span style="color:#666">.</span><span style="color:#19177c">$row</span>[<span style="color:#ba2121">'Address'</span>]<span style="color:#666">.</span><span style="color:#ba2121">'</td></tr>'</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#19177c">$html</span><span style="color:#666">.=</span><span style="color:#ba2121">'</table>'</span>;
</span></span><span style="display:flex;"><span>}
</span></span></code></code>
In the above example, we are storing data from the database in the variable $html. We used the . operator to join all table elements. So, we are ready to write HTML document to PDF.
Next, create a variable named $mpdf. Assign the object of the Mpdf() constructor to a variable using the new keyword. Call the WriteHTML() function using the $html variable as the parameter of the object. Then create another variable $file to store the PDF. Concatenate files/ with the time() function and concatenate it again with .pdf to create the filename. Store it in the $file variable. Finally, call the output() function with $file as the first argument and option I as the second argument.
Therefore, we retrieved the data from the database and created a PDF using the data. The following example creates a file named with the current time and with the extension .pdf in the files folder. After the script runs, the PDF will be displayed in the browser. We can download the PDF from the browser.
Sample code:
<code> <code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#19177c">$mpdf</span><span style="color:#666">=</span><span style="color:#008000;font-weight:bold">new</span> \Mpdf\Mpdf(); </span></span><span style="display:flex;"><span><span style="color:#19177c">$mpdf</span><span style="color:#666">-></span><span style="color:#7d9029">WriteHTML</span>(<span style="color:#19177c">$html</span>); </span></span><span style="display:flex;"><span><span style="color:#19177c">$file</span><span style="color:#666">=</span><span style="color:#ba2121">'files/'</span><span style="color:#666">.</span>time()<span style="color:#666">.</span><span style="color:#ba2121">'.pdf'</span>; </span></span><span style="display:flex;"><span><span style="color:#19177c">$mpdf</span><span style="color:#666">-></span><span style="color:#7d9029">output</span>(<span style="color:#19177c">$file</span>,<span style="color:#ba2121">'I'</span>); </span></span></code></code>
in PHP using the dompdf
dompdf library is also an option for creating and downloading PDFs in PHP. It lets us load HTML into PDF. This library is very similar to the mpdf library; just the approach is different. We will use methods like loadHtml(), render() and stream(). We need to download the library to our working directory using the command composer require dompdf/dompdf. It will create the vendor folder and the composer.<strong class="keylink">JSON</strong> and composer.lock files just like the first method.
例如，要求 vendor/autoload.php 作为程序中代码的第一行。然后编写 use 关键字以将 Dompdf 类导入为 use Dompdf/Dompdf。我们可以使用与上述方法相同的 HTML 表来加载 PDF。
<code> <code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">require</span> <span style="color:#ba2121">'vendor/autoload.php'</span>; </span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">use</span> Dompdf\Dompdf; </span></span></code></code>
将 HTML 存储在变量 $html 中后，创建另一个变量 $dompdf 以创建类 Dompdf 的对象。然后使用 $html 作为参数调用 loadHtml() 方法。接下来，调用 render() 函数，然后使用 $dompdf 对象调用 stream() 函数。
下面的示例将使用第一种方法中的表格创建 PDF。render() 方法将 HTML 呈现为 PDF 文件，而 stream() 方法将呈现的 HTML 输出到浏览器。因此，我们可以使用 PHP 中的 dompdf 库创建 PDF。
示例代码：
<code> <code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#19177c">$dompdf</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">new</span> Dompdf(); </span></span><span style="display:flex;"><span><span style="color:#19177c">$dompdf</span><span style="color:#666">-></span><span style="color:#7d9029">loadHtml</span>(<span style="color:#19177c">$html</span>); </span></span><span style="display:flex;"><span><span style="color:#19177c">$dompdf</span><span style="color:#666">-></span><span style="color:#7d9029">render</span>(); </span></span><span style="display:flex;"><span><span style="color:#19177c">$dompdf</span><span style="color:#666">-></span><span style="color:#7d9029">stream</span>(); </span></span></code></code>
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