=head1 NAME XAO::DO::Web::Page - core object of XAO::Web rendering system =head1 SYNOPSIS Outside web environment: my $page=XAO::Objects->new(objname => 'Page'); my $date=$page->expand(template => '<%Date%>'); Inside XAO::Web template: <%Page path="/bits/some-path" ARG={<%SomeObject/f%>}%> =head1 DESCRIPTION As XAO::DO::Web::Page object (from now on just Page displayable object) is the core object for XAO::Web web rendering engine we will start with basics of how it works. The goal of XAO::Web rendering engine is to produce HTML data file that can be understood by browser and displayed to a user. It will usually use database tables, templates and various displayable objects to achieve that. Every time a page is requested in someone's web browser a XAO::Web handler gets executed, prepares site configuration, opens database connection, determines what would be start object and/or start path and does a lot of other useful things. If you have not read about it yet it is suggested to do so -- see L and L. Although XAO::Web handler can call arbitrary object with arbitrary arguments to produce an HTML page we will assume the simplest scenario of calling Page object with just one argument -- path to an HTML file template for simplicity (another way to pass some template to a Page object is to pass argument named "template" with the template text as the value). This is the default behavior of XAO::Web handler if you do not override it in configuration. Let's say user asked for http://oursite.com/ and XAO::Web translated that into the call to Page's display method with "path" argument set to "/index.html". All template paths are treated relative to "templates" directory in site directory or to system-wide "templates" directory if site-specific template does not exist. Suppose templates/index.html file in our site's home directory contains the following: Hello, World! As there are no special symbols in that template Page's display method will return exactly that text without any changes (it will also cache pre-parsed template for re-use under mod_perl, but this is irrelevant for now). Now let's move to a more complex example -- suppose we want some kind of header and footer around our text: <%Page path="/bits/header-template"%> Hello, World! <%Page path="/bits/footer-template"%> Now, Page's parser sees reference to other items in that template - these things, surrounded by <% %> signs. What it does is the following. First it checks if there is an argument given to original Page's display() method named 'Page' (case sensitive). In our case there is no such argument present. Then, as no such static argument is found, it attempts to load an object named 'Page' and pass whatever arguments given to that object's display method. I it is recommended to name static arguments in all-lowercase (for standard parameters accepted by an object) or all-uppercase (for parameters that are to be included into template literally) letters to distinguish them from object names where only the first letter of every word is capitalized. In our case Page's parser will create yet another instance of Page displayable object and pass argument "path" with value "/bits/header-template". That will include the content of templates/bits/header-template file into the output. So, if the content of /bits/header-template file is: And the content of /bits/footer-template is: Then the output produced by the original Page's display would be: Hello, World! For the actual site you might opt to use specific objects for header and footer (see L and L): <%Header title="My first XAO::Web page"%> Hello, World! <%Footer%> Page's parser is not limited to only these simple cases, you can embed references to variables and objects almost everywhere. In the following example Utility object (see L) is used to build complete link to a specific page: /somepage.html">blah blah blah If current (configured or guessed) site URL is "http://demosite.com/" this template would be translated into: blah blah blah Even more interesting is that you can use embedding to create arguments for embedded objects: <%Date gmtime={<%CgiParam param="shippingtime" default="0"%>}%> If your page was called with "shippingtime=984695182" argument in the query then this code would expand to (in PST timezone): Thu Mar 15 14:26:22 2001 As you probably noticed, in the above example argument value was in curly brackets instead of quotes. Here are the options for passing values for objects' arguments: =over =item 1 You can surround value with double quotes: name="value". This is recommended for short strings that do not include any " characters. =item 2 You can surround value with matching curly brackets. Curly brackets inside are allowed and counted so that these expansions would work: name={Some text with " symbols} name={Multiple Lines} name={something <%Foo bar={test}%> alsdj} The interim brackets in the last example would be left untouched by the parser. Although this example won't work because of unmatched brackets: name={single { inside} See below for various ways to include special symbols inside of arguments. =item 3 Just like for HTML files if the value does not include any spaces or special symbols quotes can be left out: number=123 But it is not recommended to use that method and it is not guaranteed that this will remain legal in future versions. Kept mostly for compatibility with already deployed code. =item 4 To pass a string literally without performing any substitutions you can use single quotes. For instance: <%FS uri="/Members/<%MEMBER_ID/f%>" mode="show-hash" fields="*" template='<%MEMBER_AGE/f%> -- <%MEMBER_STATUS/f%>' %> If double quotes were used in this example then the parser would try to expand <%MEMBER_AGE%> and <%MEMBER_STATUS%> variables using the current object arguments which is not what is intended. Using single quotes it is possible to let FS object do the expansion and therefore insert database values in this case. =item 5 To pass multiple nested arguments literally or to include a single quote into the string matching pairs of {' and '} can be used: <%FS uri="/Members/<%MEMBER_ID/f%>" mode="show-hash" fields="*" template={'Member's age is <%MEMBER_AGE/f%>'} %> =back =head2 EMBEDDING SPECIAL CHARACTERS Sometimes it is necessary to include various special symbols into argument values. This can be done in the same way you would embed special symbols into HTML tags arguments: =over =item * By using &tag; construction, where tag could be "quot", "lt", "gt" and "amp" for double quote, left angle bracket, right angle bracket and ampersand respectfully. =item * By using &#NNN; construction where NNN is the decimal code for the corresponding symbol. For example left curly bracket could be encoded as { and right curly bracket as }. The above example should be re-written as follows to make it legal: name={single { inside} =back =head2 OUTPUT CONVERSION As the very final step in the processing of an embedded object or variable the parser will check if it has any flags and convert it accordingly. This can (and should) be used to safely pass special characters into fields, HTML documents and so on. For instance, the following code might break if you do not use flags and variable will contain a duoble quote character in it: Correct way to write it would be (note /f after VALUE): Generic format for specifying flags is: <%Object/x ...%> or <$VARIABLE/x$> Where 'x' could be one of: =over =item f Converts text for safe use in HTML elements attributes. Mnemonic for remembering - (f)ield. Will convert '123"234' into '123"234'. =item h Converts text for safe use in HTML text. Mnemonic - (H)TML. Will convert '123
234' into '123<BR>234'. =item q Converts text for safe use in HTML query parameters. Mnemonic - (q)uery. Will convert '123 234' into '123%20234'. Example: Test '<$VAR/h$>' =item s The same as 'h' excepts that it translates empty string into ' '. Suitable for inserting pieces of text into table cells. =item u The same as 'q'. Mnemonic - (U)RL, as it can be used to convert text for inclusion into URLs. =back It is a very good habit to use flags as much as possible and always specify a correct conversion. Leaving output untranslated may lead to anything from broken HTML to security violations. =head2 LEVELS OF PARSING Arguments can include as many level of embedding as you like, but you must remember: =over =item 1 That all embedded arguments are expanded from the deepest level up to the top before executing main object. =item 2 That undefined references to either non-existing object or non-existing variable produce a run-time error and the page is not shown. =item 3 All embedded arguments are processed in the same arguments space that the template one level up from them. =back As a test of how you understood everything above please attempt to predict what would be printed by the following example (after reading L or guessing its meaning). The answer is about one page down, at the end of this chapter. <%SetArg name="V1" value="{}"%> <%SetArg name="V2" value={""}%> <%Page template={<%V1%><%V2%> <%Page template={<%SetArg name="V2" value="[]" override%><%V2%>}%> <%V2%><%V1%>} %> In most cases it is not recommended to make complex inline templates though, it is usually better to move sub-templates into a separate file and include it by passing path into Page. Usually it is also more time efficient because templates with known paths are cached in parsed state first time they used while inlined templates are parsed every time. It is usually good idea to make templates as simple as possible and move most of the logic inside of objects. To comment what you're doing in various parts of template you can use normal HTML-style comments. They are removed from the output completely, so you can include any amounts of text inside of comments -- it won't impact the size of final HTML file. Here is an example: <%Header title="demosite.com"%> <%Page path="/bits/menu"%> <%Page path="/bits/body"%> <%Footer%> One exception is JavaScript code which is usually put into comments. The parser will NOT remove comments if open comment is =head2 NOTE FOR HARD-BOILED HACKERS If you do not like something in the parser behavior you can define site-specific Page object and refine or replace any methods of system Page object. Your new object would then be used by all system and site-specific objects B and won't impact any other sites installed on the same host. But this is mentioned here merely as a theoretical possibility, not as a good thing to do. =head2 TEST OUTPUT The output of the test above would be: {}"" [] ""{} In fact first two SetArg's would add two empty lines in front because they have carriage returns after them, but this is only significant if your HTML code is space-sensitive. =head1 METHODS Publicly accessible methods of Page (and therefor of all objects derived from Page unless overwritten) are: =over =cut ############################################################################### package XAO::DO::Web::Page; use strict; #use Data::Dumper; #XXX - remove use XAO::Utils; use XAO::Cache; use XAO::Templates; use XAO::Objects; use XAO::Projects qw(:all); use XAO::PageSupport; use Error qw(:try); use base XAO::Objects->load(objname => 'Atom'); use vars qw($VERSION); $VERSION=(0+sprintf('%u.%03u',(q$Id: Page.pm,v 2.1 2005/01/14 01:39:57 am Exp $ =~ /\s(\d+)\.(\d+)\s/))) || die "Bad VERSION"; ## # Prototypes # sub cache ($%); sub cgi ($); sub check_db ($); sub dbh ($); sub display ($%); sub expand ($%); sub finaltextout ($%); sub object ($%); sub odb ($); sub parse ($%); sub siteconfig ($); sub textout ($%); ############################################################################### =item display (%) Displays given template to the current output buffer. The system uses buffers to collect all text displayed by various objects in a rather optimal way using XAO::PageSupport (see L) module. In XAO::Web handler the global buffer is initialized and after all displayable objects have worked their way it retrieves whatever was accumulated in that buffer and displays it. This way you do not have to think about where your output goes as long as you do not "print" anything by yourself - you should always call either display() or textout() to print any piece of text. Display() accepts the following arguments: =over =item path => 'path/to/the/template' Gives Page a path to the template that should be processed and displayed. =item template => 'template text' Provides Page with the actual template text. =item unparsed => 1 If set it does not parse template, just displays it literally. =back Any other argument given is passed into template unmodified as a variable. Remember that it is recommended to pass variables using all-capital names for better visual recognition. Example: $obj->display(path => "/bits/left-menu", ITEM => "main"); For security reasons it is also recommended to put all sub-templates into /bits/ directory under templates tree or into "bits" subdirectory of some tree inside of templates (like /admin/bits/admin-menu). Such templates cannot be displayed from XAO::Web handler by passing their path in URL. =cut sub display ($%) { my $self=shift; my $args=$self->{args}=get_args(\@_); ## # Parsing template or getting already pre-parsed template when it is # available. # my $page=$self->parse($args); ## # Template processing itself. Pretty simple, huh? :) # foreach my $item (@{$page}) { my $stop_after; my $itemflag; my $text; if(exists $item->{text}) { $text=$item->{text}; } elsif(exists $item->{varname}) { my $varname=$item->{varname}; $text=$args->{$varname}; defined $text || throw $self "display - undefined argument '$varname'"; $itemflag=$item->{flag}; } elsif(exists $item->{objname}) { my $objname=$item->{objname}; $itemflag=$item->{flag}; ## # First we're trying to substitute from arguments # $text=$args->{$objname}; ## # Executing object if not. # if(!defined $text) { my $obj=$self->object(objname => $objname); ## # Preparing arguments. If argument includes object references - # they are expanded first. # my %objargs; my $ia=$item->{args}; my $args_copy; foreach my $a (keys %$ia) { my $v=$ia->{$a}; if(ref($v)) { if(@$v==1 && exists($v->[0]->{text})) { $v=$v->[0]->{text}; } else { if(!$args_copy) { $args_copy=merge_refs($args); delete $args_copy->{path}; } $args_copy->{template}=$v; $v=$self->expand($args_copy); } } ## # Decoding entities from arguments. Lt, gt, amp, # quot and &#DEC; are supported. # $v=~s/<//sg; $v=~s/"/"/sg; $v=~s/&#(\d+);/chr($1)/sge; $v=~s/&/&/sg; $objargs{$a}=$v; } ## # Executing object. For speed optimisation we call object's # display method directly if we're not going to do anything # with the text anyway. This way we avoid push/pop and at # least two extra memcpy's. # delete $self->{merge_args}; if($itemflag && $itemflag ne 't') { $text=$obj->expand(\%objargs); } else { $obj->display(\%objargs); } ## # Indicator that we do not need to parse or display anything # after that point. # $stop_after=$self->clipboard->get('_no_more_output'); ## # Was it something like SetArg object? Merging changes in then. # if($self->{merge_args}) { @{$args}{keys %{$self->{merge_args}}}=values %{$self->{merge_args}}; } } } ## # Safety conversion - q for query, h - for html, s - for # nbsp'ced html, f - for tag fields, u - for URLs, t - for text # as is (default). # if(defined($text) && $itemflag && $itemflag ne 't') { if($itemflag eq 'h') { $text=XAO::Utils::t2ht($text) } elsif($itemflag eq 's') { $text=(defined $text && length($text)) ? XAO::Utils::t2ht($text) : " "; } elsif($itemflag eq 'q') { $text=XAO::Utils::t2hq($text) } elsif($itemflag eq 'f') { $text=XAO::Utils::t2hf($text) } elsif($itemflag eq 'u') { $text=XAO::Utils::t2hq($text) } } ## # Sending out the text # $self->textout($text) if defined($text); ## # Checking if this object required to stop processing # last if $stop_after; } } ############################################################################### =item expand (%) Returns a string corresponding to the expanded template. Accepts exactly the same arguments as display(). Here is an example: my $str=$obj->expand(template => '<%Date%>'); =cut sub expand ($%) { my $self=shift; ## # First it prepares a place in stack for new text (push) and after # display it calls pop to get back whatever was written. The sole # reason for all this is speed optimization - XAO::PageSupport is # implemented in C in quite optimal way. # XAO::PageSupport::push(); $self->display(@_); XAO::PageSupport::pop(); } ############################################################################### =item parse ($%) Takes template from either 'path' or 'template' and parses it. If given the following template: Text <%Object a=A b="B" c={<%C/f ca={CA}%>} d='D' e={'<$E$>'}%> It will return a reference to the array of the following structure: [ { text => 'Text ', }, { objname => 'Object', args => { a => [ { text => 'A', }, ], b => [ { text => 'B', }, ], c => [ { objname => 'C', flag => 'f', args => { ca => [ { text => 'CA', }, ], }, }, ], d => 'D', e => '<$E$>', }, }, ] Templates from disk files are cached for the lifetime of the process and are never re-parsed. Always returns with a correct array or throws an error. =cut my %parsed_cache; sub parse ($%) { my $self=shift; my $args=get_args(\@_); my $sitename; ## # Getting template text # my $template; my $unparsed=$args->{unparsed}; my $path; if(defined($args->{template})) { $template=$args->{template}; if(ref($template)) { return $template; # Pre-parsed as an argument of some upper class } } else { $path=$args->{path} || throw $self "parse - no 'path' and no 'template' given to a Page object"; $sitename=$self->{sitename} || get_current_project_name(); if(!$unparsed && exists $parsed_cache{$sitename}->{$path}) { return $parsed_cache{$sitename}->{$path}; } if($self->debug_check('show-path')) { dprint $self->{objname}."::parse - path='$path'"; } $template=XAO::Templates::get(path => $path); defined($template) || throw $self "parse - no template found (path=$path)"; } ## # Checking if we do not need to parse that template. # if($unparsed) { return [ { text => $template } ]; } ## # Parsing. If a scalar is returned it is an indicator of an error. # if($self->debug_check('show-parse')) { if($path) { dprint $self->{objname}."::parse - parsing path='$path'" } else { my $te=substr($template,0,20); $te=~s/\r/\\r/sg; $te=~s/\n/\\n/sg; $te=~s/\t/\\t/sg; $te.='...' if length($template)>20; dprint $self->{objname}."::parse - parsing inline template ($te)"; } } my $page=XAO::PageSupport::parse($template); ref $page || throw $self "parse - $page"; $parsed_cache{$sitename}->{$path}=$page if $path; return $page; } ############################################################################### =item object (%) Creates new displayable object correctly tied to the current one. You should always get a reference to a displayable object by calling this method, not by using XAO::Objects' new() method. Currently most of the objects would work fine even if you do not, but this is not guaranteed. Possible arguments are (the same as for XAO::Objects' new method): =over =item objname => 'ObjectName' The name of an object you want to have an instance of. Default is 'Page'. All objects are assumed to be in XAO::DO::Web namespace, prepending them with 'Web::' is optional. =item baseobj => 1 If present then site specific object is ignored and system object is loaded. =back Example of getting Page object: sub display ($%) { my $self=shift; my $obj=$self->object; $obj->display(template => '<%Date%>'); } Or even: $self->object->display(template => '<%Date%>'); Getting FilloutForm object: sub display ($%) { my $self=shift; my $ff=$self->object(objname => 'FilloutForm'); $ff->setup(...); ... } Object() method always returns object reference or throws an exception -- meaning that under normal circumstances you do not need to worry about returned object correctness. If you get past the call to object() method then you have valid object reference on hands. =cut sub object ($%) { my $self=shift; my $args=get_args(@_); my $objname=$args->{objname} || 'Page'; $objname='Web::' . $objname unless substr($objname,0,5) eq 'Web::'; XAO::Objects->new( objname => $objname, parent => $self, ); } ############################################################################### =item textout ($) Displays a piece of text literally, without any changes. It used to be called as textout(text => "text") which is still supported for compatibility, but is not recommended any more. Call it with single argument -- text to be displayed. Example: $obj->textout("Text to be displayed"); This method is the only place where text is actually gets displayed. You can override it if you really need some other output strategy for you object. Although it is not recommended to do so. =cut sub textout ($%) { my $self=shift; return unless @_; if(@_ == 1) { XAO::PageSupport::addtext($_[0]); } else { my %args=@_; XAO::PageSupport::addtext($args{text}); } } ############################################################################### =item finaltextout ($) Displays some text and stops processing templates on all levels. No more objects should be called in this session and no more text should be printed. Used in Redirect object to break execution immediately for example. Accepts the same arguments as textout() method. =cut sub finaltextout ($%) { my $self=shift; $self->textout(@_); $self->clipboard->put(_no_more_output => 1); } ############################################################################### =item dbh () Returns current database handler or throws an error if it is not available. Example: sub display ($%) my $self=shift; my $dbh=$self->dbh; # if you got this far - you have valid DB handler on hands } =cut sub dbh ($) { my $self=shift; return $self->{dbh} if $self->{dbh}; $self->{dbh}=$self->siteconfig->dbh; return $self->{dbh} if $self->{dbh}; throw $self "dbh - no database connection"; } ############################################################################### =item odb () Returns current object database handler or throws an error if it is not available. Example: sub display ($%) { my $self=shift; my $odb=$self->odb; # ... if you got this far - you have valid DB handler on hands } =cut sub odb ($) { my $self=shift; return $self->{odb} if $self->{odb}; $self->{odb}=$self->siteconfig->odb; return $self->{odb} if $self->{odb}; throw $self "odb - requires object database connection"; } ############################################################################### =item cache (%) A shortcut that actually calls $self->siteconfig->cache. See the description of cache() in L for more details. =cut sub cache ($%) { my $self=shift; my $args=get_args(\@_); return $self->siteconfig->cache($args); } ############################################################################### =item cgi () Returns CGI object reference (see L) or throws an error if it is not available. =cut sub cgi ($) { my $self=shift; $self->siteconfig->cgi; } ############################################################################### =item clipboard () Returns clipboard object, which inherets XAO::SimpleHash methods. Use this object to pass data between various objects that work together to produce a page. Clipboard is cleaned before starting every new session. =cut sub clipboard ($) { my $self=shift; $self->siteconfig->clipboard; } ############################################################################### =item siteconfig () Returns site configuration reference. Be careful with your changes to configuration, try not to change configuration -- use clipboard to pass data between objects. See L for more details. =cut sub siteconfig ($) { my $self=shift; return $self->{siteconfig} if $self->{siteconfig}; $self->{siteconfig}=$self->{sitename} ? get_project($self->{sitename}) : get_current_project(); } ############################################################################### =item base_url (%) Returns base_url for secure or normal connection. Depends on parameter "secure" if it is set, or current state if it is not. If 'active' parameter is set then will return active URL, not the base one. In most practical cases active URL is the same as base URL except when your server is set up to answer for many domains. Base will stay at what is set in the site configuration and active will be the one taken from the Host: header. Examples: # Returns secure url in secure mode and normal # url in normal mode. # my $url=$self->base_url; # Return secure url no matter what # my $url=$self->base_url(secure => 1); # Return normal url no matter what # my $url=$self->base_url(secure => 0); # Return secure equivalent of the current active URL # my $url=$self->base_url(secure => 1, active => 1); =cut sub base_url ($;%) { my $self=shift; my $args=get_args(\@_); my $secure=$args->{secure}; $secure=$self->is_secure unless defined $secure; my $active=$args->{active}; my $url; if($secure) { $url=$active ? $self->clipboard->get('active_url_secure') : $self->siteconfig->get('base_url_secure'); } else { $url=$active ? $self->clipboard->get('active_url') : $self->siteconfig->get('base_url'); } return $url; } ############################################################################### =item is_secure () Returns 1 if the current the current connection is a secure one or 0 otherwise. =cut sub is_secure ($) { my $self=shift; return $self->cgi->https() ? 1 : 0; } ############################################################################### =item pageurl (%) Returns full URL of current page without parameters. Accepts the same arguments as base_url() method. =cut sub pageurl ($;%) { my $self=shift; my $pagedesc=$self->clipboard->get('pagedesc') || throw $self "pageurl - no Web context, needs clipboard->'pagedesc'"; my $url=$self->base_url(@_); my $uri=$pagedesc->{fullpath} || '/'; $uri="/".$uri unless substr($uri,0,1) eq '/'; return $url.$uri; } ############################################################################### sub debug_check ($$) { my $self=shift; my $type=shift; return $self->clipboard->get("debug/Web/Page/$type"); } ############################################################################### sub debug_set ($%) { my $self=shift; my $args=get_args(\@_); foreach my $type (keys %$args) { $self->clipboard->put("debug/Web/Page/$type",$args->{$type} ? 1 : 0); } } ############################################################################### 1; __END__ =back =head1 EXPORTS Nothing. =head1 AUTHOR Copyright (c) 2005 Andrew Maltsev Copyright (c) 2001-2004 Andrew Maltsev, XAO Inc. -- http://ejelta.com/xao/ =head1 SEE ALSO Recommended reading: L, L, L, L. =cut