How can I manually parse template code from PHP?

Question

Is there a way to evaluate an ExpressionEngine template using PHP in a custom plugin?

I am using the Widgets plugin and want to create a custom widget type. I would like to define the widget output using an ExpressionEngine template.

So something like:

<?php
    echo evaluateExpressionEngineTemplate('{exp:navee:nav nav_title="main-nav"}');
?>

Answer 1

I'm not familiar with Widgets, so this may or may not be helpful.

If you are writing a plugin, generally you don't need to parse your own template code. Simply call:

$variables = array(array('name' => 'adrian'));
$this->EE->TMPL->parse_variables($template, $variables);

Which will parse any variables, loops, or conditionals inside your template. Third party plugins in the tagdata code will be left intact, and parsed automatically later on in the EE parse order.

However, if you really need to fully parse your own template code (for example, I have used this when sending emails), you need to set up your own instance of the EE template library, and duplicate some of the code which EE uses internally (this is pretty much the code we use in Store):

$email_body = '<!-- your template data here -->';
$tag_vars = array(array('name' => 'adrian')); // simple variables to parse directly

// back up existing TMPL class
$this->EE->load->library('template');
$OLD_TMPL = isset($this->EE->TMPL) ? $this->EE->TMPL : NULL;
$this->EE->TMPL = new EE_Template();

// parse simple variables
$email_body = $this->EE->template->parse_variables($email_body, $tag_vars);

// pretty lame that we need to manually load snippets
$result = $this->db->select('snippet_name, snippet_contents')
    ->where('site_id', $this->config->item('site_id'))
    ->or_where('site_id', 0)
    ->get('snippets')->result_array();

$snippets = array();
foreach ($result as $row) {
    $snippets[$row['snippet_name']] = $row['snippet_contents'];
}

// merge snippets into global variables
$this->EE->config->_global_vars = array_merge($this->EE->config->_global_vars, $snippets);

// parse email contents as complete template
$this->EE->TMPL->parse($email_body);
$email_body = $this->EE->TMPL->parse_globals($this->EE->TMPL->final_template);

// restore old TMPL class
$this->EE->TMPL = $OLD_TMPL;

return $email_body; // this is your parsed template

Answer 2

Adrian's approach is certainly correct, but I should also add that I abstracted everything into Channel Data so you can parse things MUCH easier. Take a look at my Channel Data library, it makes a ton of things a lot easier.

https://github.com/objectivehtml/Channel-Data

$string = '{exp:navee:nav nav_title="main-nav"}';

$this->EE->load->driver('channel_data');
$parsed_string = $this->EE->channel_data->tmpl->parse_string($string);

Some other methods in the tmpl parser in Channel Data are...

• parse
• parse_array
• parse_switch
• parse_fieldtypes
• parse_path_variables
• parse_single_vars
• parse_var_pairs

All of my code is essentially the same as the first party, but it's been refactored so the methods are consistent and easier to work with.

Another solution is to use Stash https://github.com/croxton/Stash

{exp:stash:parse}
    {exp:navee:nav nav_title="main-nav"}
{/exp:stash:parse}

(Obviously this code would parse anyway, but you can late parse any variable with Stash, it's really powerful.)

Answer 3

I keep revisiting this answer and would like to add how I solved it in ExpressionEngine 3.

// load my own instance of TMPL as myTMPL
ee()->load->library("template", null, "myTMPL");

// get template as a string, and variables as name => value pairs
$template = ee()->myTMPL->fetch_template("mygroup", "mytemplate", false);
$variables = array("name" => "Mr. John Q. Public");

// render the template
$html = ee()->myTMPL->parse_variables($template, array($variables)); // merges variables
ee()->myTMPL->parse($html); // handles conditionals (doesn't seem to run plugins)
$html = ee()->myTMPL->parse_globals(ee()->myTMPL->final_template); // returns output