Enhance Template Parser Class Writeup in User Guide
Added two additional sections to the writeup: template parser usage notes, and view fragments.
Clarified a couple of "pseudo-variable" references.
Verified sphinx build.
Signed-off-by:James L Parry <jim_parry@bcit.ca>
diff --git a/user_guide_src/source/libraries/parser.rst b/user_guide_src/source/libraries/parser.rst
index 5af504a..23b2492 100644
--- a/user_guide_src/source/libraries/parser.rst
+++ b/user_guide_src/source/libraries/parser.rst
@@ -2,24 +2,26 @@
Template Parser Class
#####################
-The Template Parser Class enables you to parse pseudo-variables
+The Template Parser Class can perform simple text substitution for pseudo-variables
contained within your view files. It can parse simple variables or
-variable tag pairs. If you've never used a template engine,
-pseudo-variables look like this::
+variable tag pairs.
+
+If you've never used a template engine,
+pseudo-variable names are enclosed in braces, like this::
<html>
- <head>
- <title>{blog_title}</title>
- </head>
- <body>
+ <head>
+ <title>{blog_title}</title>
+ </head>
+ <body>
- <h3>{blog_heading}</h3>
+ <h3>{blog_heading}</h3>
- {blog_entries}
- <h5>{title}</h5>
- <p>{body}</p>
- {/blog_entries}
- </body>
+ {blog_entries}
+ <h5>{title}</h5>
+ <p>{body}</p>
+ {/blog_entries}
+ </body>
</html>
These variables are not actual PHP variables, but rather plain text
@@ -42,8 +44,9 @@
<div class="custom-index container"></div>
+**********************
Initializing the Class
-======================
+**********************
Like most other classes in CodeIgniter, the Parser class is initialized
in your controller using the $this->load->library function::
@@ -53,8 +56,9 @@
Once loaded, the Parser library object will be available using:
$this->parser
+*****************
Parsing templates
-=================
+*****************
You can use the ``parse()`` method to parse (or render) simple templates, like this::
@@ -74,13 +78,14 @@
There is no need to "echo" or do something with the data returned by
$this->parser->parse(). It is automatically passed to the output class
to be sent to the browser. However, if you do want the data returned
-instead of sent to the output class you can pass TRUE (boolean) to the
+instead of sent to the output class you can pass TRUE (boolean) as the
third parameter::
$string = $this->parser->parse('blog_template', $data, TRUE);
+**************
Variable Pairs
-==============
+**************
The above example code allows simple variables to be replaced. What if
you would like an entire block of variables to be repeated, with each
@@ -88,24 +93,24 @@
at the top of the page::
<html>
- <head>
- <title>{blog_title}</title>
- </head>
- <body>
+ <head>
+ <title>{blog_title}</title>
+ </head>
+ <body>
- <h3>{blog_heading}</h3>
+ <h3>{blog_heading}</h3>
- {blog_entries}
- <h5>{title}</h5>
- <p>{body}</p>
- {/blog_entries}
- </body>
+ {blog_entries}
+ <h5>{title}</h5>
+ <p>{body}</p>
+ {/blog_entries}
+ </body>
</html>
In the above code you'll notice a pair of variables: {blog_entries}
data... {/blog_entries}. In a case like this, the entire chunk of data
between these pairs would be repeated multiple times, corresponding to
-the number of rows in a result.
+the number of rows in the "blog_entries" element of the parameters array.
Parsing variable pairs is done using the identical code shown above to
parse single variables, except, you will add a multi-dimensional array
@@ -143,6 +148,117 @@
$this->parser->parse('blog_template', $data);
+***************************
+Template Parser Usage Notes
+***************************
+
+If you include substitution parameters that are not referenced in your template, they are ignored::
+
+ $template = 'Hello, {firstname} {lastname}';
+ $data = array(
+ 'title' => 'Mr',
+ 'firstname' => 'John',
+ 'lastname' => 'Doe'
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result: Hello, John Doe
+
+If you do not include a substitution parameter that is referenced in your template, the original
+pseudo-variable is shown in the result::
+
+ $template = 'Hello, {firstname} {initials} {lastname}';
+ $data = array(
+ 'title' => 'Mr',
+ 'firstname' => 'John',
+ 'lastname' => 'Doe'
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result: Hello, John {initials} Doe
+
+If you provide a string substitution parameter when an array is expected, i.e. for a variable pair,
+the substitution is done for the opening variable pair tag, but the closing variable pair
+tag is not rendered properly::
+
+ $template = 'Hello, {firstname} {lastname} ({degrees}{degree} {/degrees})';
+ $data = array(
+ 'degrees' => 'Mr',
+ 'firstname' => 'John',
+ 'lastname' => 'Doe',
+ 'titles' => array(
+ array('degree' => 'BSc'),
+ array('degree' => 'PhD')
+
+ )
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result: Hello, John Doe (Mr{degree} {/degrees})
+
+If you name one of your individual substitution parameters the same as one used inside a variable pair, the results
+may not be as expected::
+
+ $template = 'Hello, {firstname} {lastname} ({degrees}{degree} {/degrees})';
+ $data = array(
+ 'degree' => 'Mr',
+ 'firstname' => 'John',
+ 'lastname' => 'Doe',
+ 'degrees' => array(
+ array('degree' => 'BSc'),
+ array('degree' => 'PhD')
+
+ )
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result: Hello, John Doe (Mr Mr )
+
+**************
+View Fragments
+**************
+
+You do not have to use variable pairs to get the effect of iteration in your views.
+It is possible to use a view fragment for what would be inside a variable pair, and to
+control the iteration in your controller instead of in the view.
+
+An example with the iteration controlled in the view::
+
+ $template = '<ul>{menuitems}<li><a href="{link}">{title}</a></li>{/menuitems}</ul>';
+ $data = array(
+ 'menuitems' => array(
+ array('title' => 'First Link', 'link' => '/first'),
+ array('title' => 'Second Link', 'link' => '/second'),
+ )
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result:
+ - First Link
+ - Second Link
+
+An example with the iteration controlled in the controller, using a view fragment::
+
+ $temp_result = '';
+ $template1 = '<li><a href="{link}">{title}</a></li>';
+ $data1 = array(
+ array('title' => 'First Link', 'link' => '/first'),
+ array('title' => 'Second Link', 'link' => '/second'),
+ );
+ foreach ($data1 as $menuitem) {
+ $temp_result .= $this->parser->parse_string($template1, $menuitem, TRUE);
+ }
+
+ $template = '<ul>{menuitems}</ul>';
+ $data = array(
+ 'menuitems' => $temp_result
+ );
+ $this->parser->parse_string($template, $data);
+
+ Result:
+ - First Link
+ - Second Link
+
***************
Class Reference
***************
@@ -176,4 +292,4 @@
:param string $r: Right delimiter
:rtype: void
- Sets the delimiters (opening and closing) for a value "tag" in a template.
\ No newline at end of file
+ Sets the delimiters (opening and closing) for a pseudo-variable "tag" in a template.
\ No newline at end of file