I'd like to be able to replace things in a file with a regular expression using the following scheme:
I have an array:
$data = array(
'title' => 'My Cool Title',
'content' => ''
)
I also have a template (for clarity's sake, we'll assume the below is assigned to a variable $template)
<html>
<title><% title %></title>
<body><% content %></body>
</html>
I'd like to be able to use one regular expression to do the whole thing, so it can be as general as possible; The following is my stab at it (which doesn't work)
$endMarkup = preg_replace('/<% ([a-z]+) %>/',$data["\\1"], $template);
Is there a clean solution for putting associative array data into a template by array index?
With a little work before hand you can do it with a single preg_replace call:
$replacements = array();
foreach ($data as $search => $replacement) {
$replacements["/<% $search %>/"] = $replacement;
}
$endMarkup = preg_replace(
array_keys($replacements),
array_values($replacements),
$template);
You could try without regex if you wanted to. The function str_replace was made for this. If you don't understand regex this will be the best option for you.
Test data:
$data = array(
'title' => 'My Cool Title',
'content' => ''
);
$file = <<< EOF
<html>
<title><% title %></title>
<body><% content %></body>
</html>
EOF;
Function and example:
function replace_template($template, $data)
{
$replace = array_fill(0, count($data), '<%% %s %%>');
$keys = array_map('sprintf', $replace, array_keys($data));
$output = str_replace($keys, $data, $template);
return $output;
}
echo replace_template($file, $data);
Why do you want to bother with templating at all? PHP already is a templating language. Unless you're trying to rule out the possibility of code execution, everything you need is built into the language.
You can write your templates using plain PHP with short tags. You can wrap it all in a function to limit variable scope a bit. You can use import() to get a handful of variables out of an array. You can use include or require() to handle loading, parsing & inserting values into the file. You can use output buffering (ob_start()/ob_end()) to handle capturing the output in a string. Everything's built in, fast & thoroughly tested.
You can do this with preg_replace_callback(). Here is how I'd do it:
function get_data($matches) {
global $data;
return $data[$matches[1]];
}
$endMarkup = preg_replace_callback('/<% ([a-z]+) %>/', 'get_data', $template);
Or all in one line using create_function() if you prefer:
$endMarkup = preg_replace_callback('/<% ([a-z]+) %>/', create_function('$matches', 'global $data; return $data[$matches[1]];'), $template);
Related
I'm creating module for an application which will have simple custom templating with tags that will be replaced with data from a database. The field names will be different in each instance of this module. I want to know if there is a better way to do this.
The code below is what I've come up with, But I believe there must be a better way. I struggled with preg_split and preg_match_all and just hit my limit so I did it the dumb person way.
<?php
$customTemplate = "
<div>
<<This>>
<<that>>
</div>
";
function process_template ($template, $begin = '<<', $end = '>>') {
$begin_exploded = explode($begin, $template);
if (is_array($begin_exploded)) {
foreach ($begin_exploded as $key1 => $value1) {
$end_exploded = explode($end, $value1);
if (is_array($end_exploded)) {
foreach ($end_exploded as $key2 => $value2) {
$tag = $begin.$value2.$end;
$variable = trim($value2);
$find_it = strpos($template,$tag);
if ($find_it !== false) {
//str_replace ($tag, $MyClass->get($variable), $template );
$template = str_replace ($tag, $variable, $template);
}
}
}
}
}
return $template;
}
echo(process_template($customTemplate));
/* Will Echo
<div>
This
that
</div>
*/
?>
In the future I will connect $MyClass->get() to replace the tag with the proper data. And the custom template will be built by the user.
Rather than preg_split or preg_match I would rather use preg_replace_callback, since you are doing replacements, and the replacement value is derived from what looks like will end up being a method in another class.
function process_template($template, $begin = '<<', $end = '>>') {
// get $MyClass in the function scope somehow. Maybe pass it as another parameter?
return preg_replace_callback("/$begin(\w+)$end/", function($var) use ($MyClass) {
return $MyClass->get($var[1]);
}, $template);
}
Here's an example to play with: https://3v4l.org/N1p03
I assume this is just for fun/learning. If I really needed to use a template for something I would rather start with composer require "twig/twig:^2.0" instead. In fact, if you're interested in learning more about how it works you could go check out a well-established system like twig or blade does it. (Better than I've done it in this answer.)
There are tons templating engines around, but sometimes... just add complexity and dependencies for a maybe simple thing. This a modified sample of what I used for make some javascript corrections. This works for your template.
function process_template($html,$b='<<',$e='>>'){
$replace=['this'=>'<input name="this" />','that'=>'<input name="that" />'];
if(preg_match_all('/('.$b.')(.*?)('.$e.')/is',$html,$matches,PREG_SET_ORDER|PREG_OFFSET_CAPTURE)){
$t='';$o=0;
foreach($matches as $m){
//for reference $m[1][0] contains $b, $m[2][0] contains $e
$t.=substr($html,$o,$m[0][1]-$o);
$t.=$replace[$m[2][0]];
$o=$m[3][1]+strlen($m[3][0]);
}
$t.=substr($html,$o);
$html=$t;
}
return $html;
}
$html="
<div>
<<this>>
<<that>>
</div>
";
$new=process_template($html);
echo $new;
For demo purpose I put the array $replace that handling the substitutions. You replace those with your function that will handle the replacement.
Here is a working snippet: https://3v4l.org/MBnbR
I like this function because you have control of what to replace and what to put back on the final result. By the way by using the PREG_OFFSET_CAPTURE also return on the matches the position where the regexp groups happens. Those are on the $m[x][1]. The captured text will be on $m[x][0].
im using this php code (from a question on here):
<?php
define(TEMPLATES_LOCATION, 'templates/');
function TemplateFunction ($template, $replaces) {
$template = file_get_contents(TEMPLATES_LOCATION . $template);
if (is_array($replaces)) {
foreach($replaces as $replacekey => $replacevalue){
$template = str_replace('{$' . $replacekey . '}', $replacevalue, $template);
}
}
return $template;
}
$keys = array(
'TITLE' => 'This is page title',
'HEADER' => 'This is some header',
'GALLERY' => 'php while loop here'
);
echo TemplateFunction('body.tpl', $keys);
?>
The way my template file is set up is the following HTML:
<body>
<div id="gallery">{GALLERY}</div>
</body>
so where {GALLERY} is, the php script should replace that with my automatically generated <li><img src="images/'.$filename.'"/></li> which is being run in a while loop generated from a mysql request
what i thought might work is:
$keys = array(
'TITLE' => 'This is page title',
'HEADER' => 'This is some header',
'GALLERY' => 'while($row = mysql_fetch_array($result)){<li><img src="'.$row['filename'].'"/></li>})'
);
but it doesnt :(
Re your code:
$keys = array(
'TITLE' => 'This is page title',
'HEADER' => 'This is some header',
'GALLERY' => 'while($row = mysql_fetch_array($result)){<li><img src="'.$row['filename'].'"/></li>})'
);
I would consider it very poor practice to have PHP code embedded in your template data this way. Allow me to offer you a completely different solution...
Firstly, we need to encapsulate the code. The code you've shown above is trying to fetch data from a $result variable, but $result itself is obviously been set elsewhere. This isn't good, because if we ever want to change the way the gallery feature works, we would need to search all over the code to find different bits of it.
Instead, you should write the feature as a self-contained function (or a class if it's too complex for a single function), which would load the data, and process it.
Let's call that function loadGallery(). It might look something like this:
function loadGallery() {
$output = '';
$result = mysql_query('...gallery query here...');
while($row = mysql_fetch_array($result)) {
$output .= "<li><img src='{$row['filename']}'/></li>";
}
return '<ul>'.$output.'</ul>';
}
Obviously, it could be a lot more complex than that (eg you may want to paginate it, or offer category options; these would be written as parameters for the function). I've also not written any error checking, etc here for brevity.
Now that you've got that function, you can plug it into the template engine. You need to reference the function in your template.
You currently have template markers like this {TITLE}. In your code, these markers are swapped with plain text using str_replace(). That's fine. But in this case we now want to call a function instead, so we need to have a different kind of marker.
Let's write the gallery marker like this: {FUNCTION:loadGallery} instead of {GALLERY} as you currently have.
Now you can have an additional bit of code in your template engine that looks at these {function:} markers and replaces them with a function call. (You can keep the existing simple str_replace() method as well of course)
$funcReplaces = array( //similar to your existing $keys array, but for allowed functions
'loadGallery'
);
foreach($funcReplaces as $replaceFunc){
$template = str_replace('{function:' . $replaceFunc . '}', $replaceFunc(), $template);
}
This will run the function and put the output into the template.
So that answers the question for you.
What I should point out, however, is that there are a lot of other issues that you need to think about when writing a templating engine, from both a technical and security perspective. The above describes a basic way to resolve the specific question at hand, but it isn't a fantastic all-singing all-dancing template engine. It's still just a pretty basic one.
That's fine, if that's all you need, but if you expect this system to grow, it's worth noting that this whole area is that this is very much a problem that others have already solved, and solved well. There are several very good templating engines available for PHP. I would suggest that your best course of action would be to investigate some of them, and maybe use one of those instead of writing your own.
Some that you could try:
Smarty
Twig
Mustache
Hope that helps.
You cannot "execute PHP code within an array". You simply build the array programmatically:
while (/* something */) {
$keys['GALLERY'][] = $something;
}
I have found the following code that i've written to be the right solution to my issue:
$gallery = array();
while($row = mysql_fetch_assoc($result))
{
$gallery[] = '<li><img src="'.$row['gallery_image_filename'].'" width="'.$final_image_width.'" height="auto" style="margin: '.$other_margin.'px '.$gallery_image_margin.'px '.$other_margin.'px 0px"/></li>';
}
$gallery = implode(' ', $gallery);
i then can concatenate my $gallery variable into the 'GALLERY' => 'value' value and it outputs all the database results as required. Thanks to all for your help :)
Well, you can create an class with __toString magic method which will process all images on your gallery and then return the string.
class TemplateGallery{
private $images = array();
public function addImage($src){
$images[] = $src;
}
public function __toString(){
$str = "";
foreach($images as $image){
$str .= sprintf('<li><img src="%s"></li>',$image);
}
return $str;
}
}
Well, as the guy in comments said, it's too "hard", so, you can use an "pre-process" function, that will process your images array, and then return your template string.
$images = array(/* Put images src here */);
function processGallery($images){
$str = "";
foreach($images as $image){
$str .= sprintf('<li><img src="%s"></li>',$image);
}
return $str;
}
And then call that function on your array.
I am creating an OpenCart extension where the admin can change his email templates using the user interface in the admin panel.
I would like the user to have the option to add variables to his custom email templates. For example he could put in:
Hello $order['customer_firstname'], your order has been processed.
At this point $order would be undefined, the user is simply telling defining the message that is to be sent. This would be stored to the database and called when the email is to be sent.
The problem is, how do I get "$order['customer_firstname']" to become a litteral string, and then be converted to a variable when necessary?
Thanks
Peter
If I understand your question correctly, you could do something like this:
The customer has a textarea or similar to input the template
Dear %NAME%, blah blah %SOMETHING%
Then you could have
$values = array('%SOMETHING%' => $order['something'], '%NAME%' => $order['name']);
$str = str_replace(array_keys($values), array_values($values), $str);
the user will be using around 40 variables. Is there a way I can set it to do that for each "%VARIABLE%"?
Yes, you can do so for each variable easily with the help of a callback function.
This allows you, to process each match with a function of your choice, returning the desired replacement.
$processed = preg_replace_callback("/%(\S+)%/", function($matches) {
$name = $matches[1]; // between the % signs
$replacement = get_replacement_if_valid($name);
return $replacement;
},
$text_to_replace_in
);
From here, you can do anything you like, dot notation, for example:
function get_replacement_if_valid($name) {
list($var, $key) = explode(".", $name);
if ($var === "order") {
$order = init_oder(); // symbolic
if(array_key_exists($key, $order)) {
return $order[$key];
}
}
return "<invalid key: $name>";
}
This simplistic implementation allows you, to process replacements such as %order.name% substituting them with $order['name'].
You could define your own simple template engine:
function template($text, $context) {
$tags = preg_match_all('~%([a-zA-Z0-9]+)\.([a-zA-Z0-9]+)%~', $text, $matches);
for($i = 0; $i < count($matches[0]); $i++) {
$subject = $matches[0][$i];
$ctx = $matches[1][$i];
$key = $matches[3][$i];
$value = $context[$ctx][$key];
$text = str_replace($subject, $value, $text);
}
return $text;
}
This allows you to transform a string like this:
$text = 'Hello %order.name%. You have %order.percent%% discount. Pay a total ammount of %payment.ammount% using %payment.type%.';
$templated = template($text, array(
'order' => array(
'name' => 'Alex',
'percent' => 20
),
'payment' => array(
'type' => 'VISA',
'ammount' => '$299.9'
)
));
echo $templated;
Into this:
Hello Alex. You have 20% discount. Pay a total ammount of $299.9 using VISA.
This allows you to have any number of variables defined.
If you want to keep the PHP-syntax, then a regex would be appropriate to filter them:
$text = preg_replace(
"/ [$] (\w+) \[ '? (\w+) \'? \] /exi",
"$$1['$2']", # basically a constrained eval
$text
);
Note that it needs to be executed in the same scope as $order is defined. Else (and preferrably) use preg_replace_callback instead for maximum flexibility.
You could also allow another syntax this way. For example {order[customer]} or %order.customer% is more common and possibly easier to use than the PHP syntax.
You can store it as Hello $order['customer_firstname'] and while accessing make sure you have double-quotes "" to convert the variable to its corresponding value.
echo "Hello $order['customer_firstname']";
Edit: As per the comments, a variation to Prash's answer,
str_replace('%CUSTOMERNAME%', $order['customer_name'], $str);
What you're looking for is:
eval("echo \"" . $input . "\";");
but please, PLEASE don't do that, because that lets the user run any code he wants.
A much better way would be a custom template-ish system, where you provide a list of available values for the user to drop in the code using something like %user_firstname%. Then, you can use str_replace and friends to swap those tags out with the actual values, but you can still scan for any sort of malicious code.
This is why Markdown and similar are popular; they give the user control over presentation of his content while still making it easy to scan for HTML/JS/PHP/SQL injection/anything else they might try to sneak in, because whitelisting is easier than blacklisting.
Perhaps you can have a template like this:
$tpl = "Hello {$order['customer_firstname']}, your order has been processed.".
If $order and that specific key is not null, you can use echo $tpl directly and show the content of 'customer_firstname' key in the text. The key are the curly braces here.
I'm writing a mail class that pulls content stored in a database and loads it into a template before sending it as a HTML e-mail. However, because each e-mail contains PHP variables and dynamic content, I've decided to use delimiters. So instead of the content looking like:
Hello $username, welcome to the site.
It'll look like:
Hello {{username}}, welcome to the site.
So far I'm using these methods:
function load($name,$content)
{
// preps the template for HTML
}
function content($template_id)
{
$template = $this->db->get_where('email_templates',array('id'=>$template_id));
return $template->content;
}
function new_email($email,$name,$user_type)
{
$msg = $this->load($name,$this->content(1));
$this->send($email,'Thanks for your application',$msg,1);
}
The trouble I'm having is how to convert a {{variable}} into a $variable so that it will parse - I don't want it to just be loaded as $username in the e-mail template. Is it just a case of using regular expressions and escaping the string so that it'll parse? Something like:
$content = str_replace("{{","'.$",$template->content);
$content = str_replace("}}",".'",$template->content);
Or is this flawed? Does anybody know what's the best thing to do?
I would not create my own templating system, because there are existing ones out there.
The most popular is probably Smarty, but there is an another one which has the same format as you created, that is mustache.
Update:
The problem with your code is that you're replacing the {{ to a .$ and store that in $content variable, then replacing }} to . and overwrite this replaced $content variable.
A possible working solution could be:
if (preg_match_all("/{{(.*?)}}/", $template, $m)) {
foreach ($m[1] as $i => $varname) {
$template = str_replace($m[0][$i], sprintf('$%s', $varname), $template);
}
}
But then you would also need to eval your code somehow.
So after converting {{variable}} to $variable in your email template, you will use eval to get it replaced by the actual contents of that variable?
Why not just replace {{variable}} with the contents of $variable straight away?
Perhaps have a function that takes the template text and an array of placeholder => "text to replace it with". Then it's as simple as making up the placeholders' exact strings by adding {{ and }} around that array's key and doing str_replace.
foreach ($replacements as $placeholder => $value) {
$placeholder = "{{" . $placeholder . "}}" ;
$text = str_replace($placeholder, $value, $text) ;
}
Couple this with (class) constants for the placeholders and you have a very solid and typo-repelant templating system. It will not be as elegant or easy to use as a full blown templating solution, and it might require extra work from whoever writes code that uses it, but they will not make mistakes during development due to mis-named variables.
If you are going to do it yourself it is probably best to just be explicit with str_replace. If you try to convert the curly bracers to $ you'll then need to eval() which is a potential security hole.
This would be my approach with str_replace - this becomes difficult to maintain as you add more variables but it really doesn't get much simpler either.
$content = str_replace(
array('{{username}}','{{var2}}'),
array($username,$var2),
$template->content
);
use preg_replace_callback , see : http://codepad.org/EvzwTqzJ
<?php
$myTemplateStr = "Hello {{username}} , this is {{subject}} ,and other string {{example}}";
$tagRegex = "|{{(.*?)}}|is";
$result = preg_replace_callback($tagRegex,"myReplaceFunc",$myTemplateStr);
echo $result ;
/* output :
Hello $username , this is $subject ,and other string {{example}}
*/
function myReplaceFunc($matches)
{
$validTags = array('username','subject','name');
$theFull = $matches[0];
$theTag = $matches[1];
if(in_array($theTag,$validTags) == true)
return '$'.$theTag;
return $theFull ;
}
?>
$template = "Hello {{username}} , this is {{subject}} ,and other the answer is on page {{example}}";
$replacements = array(
'username' => 'Jeffrey',
'subject' => 'your final notice',
'page' => 43
);
function bind_to_template($replacements, $template) {
return preg_replace_callback('/{{(.+?)}}/',
function($matches) use ($replacements) {
return $replacements[$matches[1]];
}, $template);
}
echo bind_to_template($replacements, $template);
Credit to https://www.labnol.org/code/19266-php-templates
I'm searching for a very basic PHP templating system. Right now I'm using:
/**
* Renders a single line. Looks for {{ var }}
*
* #param string $string
* #param array $parameters
*
* #return string
*/
function renderString($string, array $parameters)
{
$replacer = function ($match) use ($parameters)
{
return isset($parameters[$match[1]]) ? $parameters[$match[1]] : $match[0];
};
return preg_replace_callback('/{{\s*(.+?)\s*}}/', $replacer, $string);
}
(from here: PHP - Extremely light templating system)
but I can only assign and display variables. I also need a way to use conditions like IF and loop arrays.
I found Rain TPL - http://www.raintpl.com/Quick-Start/#if - which is very close to what I'm looking for, but there are a few things that I don't like it it:
it allows the dude who is writing the template to run PHP functions (inside the IF condition).
it writes cache and php files, which I don't want
So, is there anything out there similar to this, but even more "basic", strict, and more secure?
Twig might be for you.
It can do conditions, and has a sandbox mode for untrusted code.
It does compilation and caching, but that seems to be possible to turn off.
There's also a Mustache port for PHP. The PHP port is here. The syntax is similar to what you're already doing, and supports simple IF and FOREACH-type loops.
And, does it without eval.
Have a look at Twig or H2O.
http://www.twig-project.org/
http://www.h2o-template.org/
From your requirements I am guessing you are wanting your website users to write some basic php scripts. You might not find a free template engine that does that.
I think it's better for you if you change an existing template engine to your needs.
You can change Rain TPL to disable some of its features that you don't want. For example you can do...
Disable function use in IF statements:
a. Locate elseif( preg_match( '/\{if(?: condition){0,1}="([^"]*)"\}/', $html, $code ) ){
b. Replace $this->function_check( $tag ); with a new method something like $this->ifcondition_function_check( $tag );
c. Create the new method that will disable all functions in IF statements.
private function ifcondition_function_check($code)
{
$preg = '/[a-zA-z0-9]+\((.*?)\)/';
if (preg_match( $preg, $code, $match ) ){
// find the line of the error
$line = 0;
$rows=explode("\n",$this->tpl['source']);
while( !strpos($rows[$line],$code) )
$line++;
// draw the error line
$error = str_replace( array('<','>'), array( '<','>' ), array($code,$rows[$line]) );
$error = str_replace( $code, "<font color=red>$code</font>", $rows[$line] );
// debug the error and stop the execution of the script
die( "<div>RainTPL Sandbox Error in template <b>{$this->tpl['tpl_filename']}</b> at line $line : <i>$error</i></b>" );
}
}
d. Now functions are disabled.
Remove the cache file. (The cache file in Rain TPL is a PHP file with the template tags replaced by PHP code)
a. Go to method draw()
b. Locate unset( $this->tpl );
c. Just before this line remove the complied (cache) file #unlink($this->tpl['compiled_filename']);.
d. Now the cache file is just a temporary file to execute the PHP code.
Hope this helps
very easy to use
http://www.smarty.net/
When you want it really small and flexible maybe the best is to stay with your own stuff? I like handcrafting ;-) You can extend your existing function. Following, your function plus if and loop statement and escaping of variables for security:
<?php
function renderString($str, $parms)
{
// if
$str = preg_replace_callback('/{{if (?P<name>\w+)}}(?P<inner>.*?){{endif}}/is', function($match) use ($parms) {
if( isset($parms[$match['name']])) {
// recursive
return renderString($match['inner'], $parms);
}
}, $str);
// loop
$str = preg_replace_callback('/{{loop (?P<name>\w+)}}(?P<inner>.*?){{endloop}}/is', function($match) use ($parms) {
if( isset($parms[$match['name']]) && is_array($parms[$match['name']])) {
$str = '';
foreach ($parms[$match['name']] as $value) {
$parms['loop'] = $value;
// recursive
$str .= renderString($match['inner'], $parms);
}
return $str;
}
}, $str);
// var
$str = preg_replace_callback('/{{(?P<name>\w+)}}/is', function($match) use ($parms) {
if( isset($parms[$match['name']])) {
return htmlspecialchars($parms[$match['name']]);
}
}, $str);
return $str;
}
$template = "<h1>{{title}}</h1>
{{if optional}}
<p>Optional: {{optional}}</p>
{{endif}}
{{if noop}}I'm not there{{endif}}
<ul>
{{loop numbers}}
<li>{{symbol}} {{loop}}</li>
{{endloop}}
</ul>";
echo renderString($template, array(
'title' => 'The Title',
'optional' => 'I am optional',
'numbers' => array( 'one', 'two', 'three'),
'symbol' => '>',
));
This script is tested in PHP 5.3 and you can copy it 1:1 to a file to play with it.
try PHPTAL: http://phptal.org/
the syntax for TAL templates does not break html, so you - and the designers can check if they going to look good.
see also:
http://wiki.zope.org/ZPT/TALSpecification14
http://wiki.zope.org/ZPT/TAL