The requirements


<ol>
<li>
libcgicpp - CGI/C++ library 
</li>
<li>
Apache2 virtual host configured for cgi 
</li>
<li>
MySQL client and server, MySQL C client library, MySQLC++ library
</li>
<li>
HTML template
</li>
</ol>



We have already covered items 1 and 2 from Part 1 of this blog series. If you need to read them, it can be found here <a 

href="https://kahimyang.com/kauswagan/HowtoBlogs.xhtml?b=641" target="_blank" 

class="news_link">https://kahimyang.com/kauswagan/HowtoBlogs.xhtml?b=641</a>.



Now we will explore how to read a file (our HTML template), read MySQL database records to replace sections of our template, and 

render them via CGI, all using C/C++. 



Install MySQL and MySQL C/C++ client library.



<pre class="brush: bash">

 # As always update Debian repositories
 apt-get update

 # Install 
 apt-get install mysql-client mysqld-server libmysqlclient-dev 
 libmysqlclient16 libmysql++-dev libmysql++-doc libmysql++3

</pre>



MySQL will prompt for your root password. Enter any desired database root password.



We now have a database server and client. Next create database and tables. Visit the <a href="http://dev.mysql.com/doc/" 

target="_blank" class="news_link">mysql documentation</a> to learn more about databases and tables and etc. For the purposes of 

this blog, we assume that you already created a database and a table called html. We also assume that this table has 

columns with names html_page_id, html_content, html_meta_title, and html_meta_description.



Access database records with MySQL C++ library



<pre class="brush: cpp">

 string html,title,description;	

 Connection conn (false);
 if (!conn.connect ("demodatabase","localhost",
 "demouser","demopassword")) {
 cout << conn.error () << endl;
 return 1;
 }

 Query query = conn.query ("select * from html where html_page_id=1");
 StoreQueryResult result = query.store ();

 if (result.num_rows () >= 1) {
 html = (string)result [0]["html_content"];
 title = (string)result [0]["html_meta_title"];
 description = (string)result [0]["html_meta_description"];
 }
 

</pre>





Our HTML template file. This is our main content. Sections with [[xxxxx]] pattern are replaced with data from our 

MySQL table. 



<pre class="brush: xml">

&lt;html>
&lt;head>
 &lt;title>[[META-TITLE]]&lt;/title>
 &lt;meta name="description" content="[[META-DESCRIPTION]]" />
&lt;/head>
&lt;body>
&lt;div style="vertical-align:top">
&lt;table>
&lt;tr>
	&lt;td>
		Static/fixed content
	&lt;/td>
	&lt;td>
 		[[PAGE-CONTENT]]
	&lt;/td> 
&lt;/tr>
&lt;/table>
&lt;/div>
&lt;/body>
&lt;/html> 

</pre>



This is a very simple template made for demonstration purposes only. Actual template files could be a lot larger.



Read HTML template file. This HTML template file is read by our C++ code shown below.




<pre class="brush: cpp">

 ifstream ifile;

 string line;
 char c;

 ifile.open ("templates/part2.html",ifstream::in);
 
 while (ifile.good()) {
 c = ifile.get ();
 if (c != EOF) {
 line += c; 
 }
 }

 ifile.close ();

</pre>




We stored our templates in templates/. We read our template one character at a time. Please see the <a 

href="http://www.cplusplus.com/reference/iostream/ifstream/" target="_blank" class="news_link">ifstream documentation</a> for 

other ways to read file content.



Putting it all together



<pre class="brush: cpp">

#include &lt;iostream>
#include &lt;fstream>

#include &lt;mysql++.h>
#include &lt;Cgicc.h>
#include &lt;HTTPHTMLHeader.h>
#include &lt;HTMLClasses.h>
#include &lt;CgiDefs.h>


#include &lt;stdlib.h>
#include &lt;stdio.h>

using namespace std;
using namespace mysqlpp;
using namespace cgicc;

int main (int argc, char **argv) {

 cout << HTTPHTMLHeader ();
 cout << HTMLDoctype (HTMLDoctype::eStrict);

 string html,title,description;

 try {
 Connection conn (false);
 if (!conn.connect ("demodatabase",
 "localhost","demouser","demopassword")) {
 cout << conn.error () << endl;
 return 1;
 }

 Query query = conn.query 
 ("select * from html where html_page_id=1");
 StoreQueryResult result = query.store ();
 

 if (result.num_rows () >= 1) {
 html = (string)result [0]["html_content"];
 title = (string)result [0]["html_meta_title"];
 description = 
 (string)result [0]["html_meta_description"];
 }
 }
 catch (exception& e) {

 cout << e.what () << endl;
 return 1;
 
 }


 string line;

 try {

 char c;
 ifstream ifile; 

 ifile.open ("templates/part2.html",ifstream::in);

 while (ifile.good()) {
 c = ifile.get ();
 if (c != EOF) {
	 line += c; 
 }
 }
 
 ifile.close ();
 }
 catch (exception& e) {

 cout << e.what () << endl;
 return 1;

 }

 
 const string content="[[PAGE-CONTENT]]";
 const string pageTitle="[[META-TITLE]]";
 const string metaDescription="[[META-DESCRIPTION]]";

 try {

 int found = line.find (content);
 if (found) {
 line.replace (found,content.length(), html); 
 }

 found = line.find (pageTitle);
 if (found) {
 line.replace (found,pageTitle.length(), title); 
 }

 found = line.find (metaDescription);
 if (found) {
 line.replace 
 (found,metaDescription.length(), description); 
 }

 }
 catch (exception& e) {
 cout << e.what () << endl;
 return 1;
 }

 cout << line << endl;

 
 return 0;
}

</pre>




To build the above code, we use a Makefile shown below



<pre class="brush: cpp">

CXX := g++ 
CXXFLAGS := -I/usr/include/mysql -I /usr/include/mysql++ -I/usr/include/cgicc -g
LDFLAGS := -L/usr/lib -lmysqlpp -lmysqlclient -lcgicc -lm

all: part2

part2: part2.cpp
	g++ $(CXXFLAGS) $(LDFLAGS) -o part2.cgi part2.cpp

clean: rm -f *.o

</pre>



Please check you man pages for information about the linker options. Output of this blog can be found below.




<a href="http://demo.kahimyang.info/cgi-cpp/part2/part2.cgi" target="_blank" 

class="news_link">http://demo.kahimyang.info/cgi-cpp/part2/part2.cgi</a>



That's it. Good luck.

Using MySQL data to populate sections of HTML template and render page with CGI C++