NAME HTML::Element::Library - HTML::Element convenience functions SYNOPSIS use HTML::Element::Library; use HTML::TreeBuilder; DESCRIPTION This method provides API calls for common actions on trees when using HTML::Tree. METHODS The test suite contains examples of each of these methods in a file "t/$method.t" Positional Querying Methods $elem->siblings Return a list of all nodes under the same parent. $elem->sibdex Return the index of $elem into the array of siblings of which it is a part. HTML::ElementSuper calls this method "addr" but I don't think that is a descriptive name. And such naming is deceptively close to the "address" function of "HTML::Element". HOWEVER, in the interest of backwards compatibility, both methods are available. $elem->addr Same as sibdex $elem->position() Returns the coordinates of this element in the tree it inhabits. This is accomplished by succesively calling addr() on ancestor elements until either a) an element that does not support these methods is found, or b) there are no more parents. The resulting list is the n-dimensional coordinates of the element in the tree. Element Decoration Methods HTML::Element::Library::super_literal($text) In HTML::Element, Sean Burke discusses super-literals. They are text which does not get escaped. Great for includng Javascript in HTML. Also great for including foreign language into a document. So, you basically toss "super_literal" your text and back comes your text wrapped in a "~literal" element. One of these days, I'll around to writing a nice "EXPORT" section. Tree Rewriting Methods $elem->replace_content($new_elem) Replaces all of $elem's content with $new_elem. $elem->wrap_content($wrapper_element) Wraps the existing content in the provided element. If the provided element happens to be a non-element, a push_content is performed instead. $elem->set_child_content(@look_down, $content) This method looks down $tree using the criteria specified in @look_down using the the HTML::Element look_down() method. After finding the node, it detaches the node's content and pushes $content as the node's content. $tree->content_handler($sid_value , $content) This is a convenience method. Because the look_down criteria will often simply be: id => 'fixme' to find things like: replace_content You can call this method to shorten your typing a bit. You can simply type $elem->content_handler( fixme => 'new text' ) Instead of typing: $elem->set_child_content(sid => 'fixme', 'new text') $tree->highlander($subtree_span_id, $conditionals, @conditionals_args) This allows for "if-then-else" style processing. Highlander was a movie in which only one would survive. Well, in terms of a tree when looking at a structure that you want to process in "if-then-else" style, only one child will survive. For example, given this HTML template: Hello, does your mother know you're using her AOL account? Sorry, you're not old enough to enter (and too dumb to lie about your age) Welcome We only want one child of the "span" tag with id "age_dialog" to remain based on the age of the person visiting the page. So, let's setup a call that will prune the subtree as a function of age: sub process_page { my $age = shift; my $tree = HTML::TreeBuilder->new_from_file('t/html/highlander.html'); $tree->highlander (age_dialog => [ under10 => sub { $_[0] < 10} , under18 => sub { $_[0] < 18} , welcome => sub { 1 } ], $age ); And there we have it. If the age is less than 10, then the node with id "under10" remains. For age less than 18, the node with id "under18" remains. Otherwise our "else" condition fires and the child with id "welcome" remains. Tree-Building Methods: Single ("li") Iteration This is best described by example. Given this HTML: Here are the things I need from the store: We can unroll it like so: my $li = $tree->look_down(id => 'store_items'); my @items = qw(bread butter vodka); $tree->iter($li, @items); To produce this: Here are the things I need from the store: Tree-Building Methods: Select Unrolling The "unroll_select" method has this API: $tree->unroll_select( select_label => $id_label, option_value => $closure, # how to get option value from data row option_content => $closure, # how to get option content from data row option_selected => $closure, # boolean to decide if SELECTED data => $data # the data to be put into the SELECT data_iter => $closure # the thing that will get a row of data ); Here's an example: $tree->unroll_select( select_label => 'clan_list', option_value => sub { my $row = shift; $row->clan_id }, option_content => sub { my $row = shift; $row->clan_name }, option_selected => sub { my $row = shift; $row->selected }, data => \@query_results, data_iter => sub { my $data = shift; $data->next } ) Tree-Building Methods: Table Generation Matthew Sisk has a much more intuitive (imperative) way to generate tables via his module HTML::ElementTable. However, for those with callback fever, the following method is available. First, we look at a nuts and bolts way to build a table using only standard HTML::Tree API calls. Then the "table" method available here is discussed. Sample Model package Simple::Class; use Set::Array; my @name = qw(bob bill brian babette bobo bix); my @age = qw(99 12 44 52 12 43); my @weight = qw(99 52 80 124 120 230); sub new { my $this = shift; bless {}, ref($this) || $this; } sub load_data { my @data; for (0 .. 5) { push @data, { age => $age[rand $#age] + int rand 20, name => shift @name, weight => $weight[rand $#weight] + int rand 40 } } Set::Array->new(@data); } 1; Sample Usage: my $data = Simple::Class->load_data; ++$_->{age} for @$data Inline Code to Unroll a Table HTML
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The manual way (*NOT* recommended) require 'simple-class.pl'; use HTML::Seamstress; # load the view my $seamstress = HTML::Seamstress->new_from_file('simple.html'); # load the model my $o = Simple::Class->new; my $data = $o->load_data; # find the and my $table_node = $seamstress->look_down('id', 'load_data'); my $iter_node = $table_node->look_down('id', 'iterate'); my $table_parent = $table_node->parent; # drop the sample
and from the HTML # only add them in if there is data in the model # this is achieved via the $add_table flag $table_node->detach; $iter_node->detach; my $add_table; # Get a row of model data while (my $row = shift @$data) { # We got row data. Set the flag indicating ok to hook the table into the HTML ++$add_table; # clone the sample my $new_iter_node = $iter_node->clone; # find the tags labeled name age and weight and # set their content to the row data $new_iter_node->content_handler($_ => $row->{$_}) for qw(name age weight); $table_node->push_content($new_iter_node); } # reattach the table to the HTML tree if we loaded data into some table rows $table_parent->push_content($table_node) if $add_table; print $seamstress->as_HTML; $tree->table() : API call to Unroll a Table require 'simple-class.pl'; use HTML::Seamstress; # load the view my $seamstress = HTML::Seamstress->new_from_file('simple.html'); # load the model my $o = Simple::Class->new; $seamstress->table ( # tell seamstress where to find the table, via the method call # ->look_down('id', $gi_table). Seamstress detaches the table from the # HTML tree automatically if no table rows can be built gi_table => 'load_data', # tell seamstress where to find the tr. This is a bit useless as # the usually can be found as the first child of the parent gi_tr => 'iterate', # the model data to be pushed into the table table_data => $o->load_data, # the way to take the model data and obtain one row # if the table data were a hashref, we would do: # my $key = (keys %$data)[0]; my $val = $data->{$key}; delete $data->{$key} tr_data => sub { my ($self, $data) = @_; shift(@{$data}) ; }, # the way to take a row of data and fill the
tags td_data => sub { my ($tr_node, $tr_data) = @_; $tr_node->content_handler($_ => $tr_data->{$_}) for qw(name age weight) } ); print $seamstress->as_HTML; Looping over Multiple Sample Rows * HTML
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* Only one change to last API call. This: gi_tr => 'iterate', becomes this: gi_tr => ['iterate1', 'iterate2'] $tree->table2() : New API Call to Unroll a Table After 2 or 3 years with "table()", I began to develop production websites with it and decided it needed a cleaner interface, particularly in the area of handling the fact that "id" tags will be the same after cloning a table row. First, I will give a dry listing of the function's argument parameters. This will not be educational most likely. A better way to understand how to use the function is to read through the incremental unrolling of the function's interface given in conversational style after the dry listing. But take your pick. It's the same information given in two different ways. Dry/technical parameter documentation "$tree->table2(%param)" takes the following arguments: * "table_ld => $look_down" : optional How to find the "table" element in $tree. If $look_down is an arrayref, then use "look_down". If it is a CODE ref, then call it, passing it $tree. Defaults to "['_tag' => 'table']" if not passed in. * "table_data => $tabular_data" : required The data to fill the table with. *Must* be passed in. * "table_proc => $code_ref" : not implemented A subroutine to do something to the table once it is found. Not currently implemented. Not obviously necessary. Just created because there is a "tr_proc" and "td_proc". * "tr_ld => $look_down" : optional Same as "table_ld" but for finding the table row elements. Please note that the "tr_ld" is done on the table node that was found below *instead* of the whole HTML tree. This makes sense. The "tr"s that you want exist below the table that was just found. * "tr_data => $code_ref" : optional How to take the "table_data" and return a row. Defaults to: sub { my ($self, $data) = @_; shift(@{$data}) ; } * "tr_proc => $code_ref" : optional Something to do to the table row we are about to add to the table we are making. Defaults to a routine which makes the "id" attribute unique: sub { my ($self, $tr, $tr_data, $row_count, $root_id) = @_; $tr->attr(id => sprintf "%s_%d", $root_id, $row_count); } * "td_proc => $code_ref" : required This coderef will take the row of data and operate on the "td" cells that are children of the "tr". See "t/table2.t" for several usage examples. Conversational parameter documentation The first thing you need is a table. So we need a look down for that. If you don't give one, it defaults to ['_tag' => 'table'] What good is a table to display in without data to display?! So you must supply a scalar representing your tabular data source. This scalar might be an array reference, a "next"able iterator, a DBI statement handle. Whatever it is, it can be iterated through to build up rows of table data. These two required fields (the way to find the table and the data to display in the table) are "table_ld" and "table_data" respectively. A little more on "table_ld". If this happens to be a CODE ref, then execution of the code ref is presumed to return the "HTML::Element" representing the table in the HTML tree. Next, we get the row or rows which serve as sample "tr" elements by doing a "look_down" from the "table_elem". While normally one sample row is enough to unroll a table, consider when you have alternating table rows. This API call would need one of each row so that it can cycle through the sample rows as it loops through the data. Alternatively, you could always just use one row and make the necessary changes to the single "tr" row by mutating the element in "tr_proc", discussed below. The default "tr_ld" is "['_tag' => 'tr']" but you can overwrite it. Note well, if you overwrite it with a subroutine, then it is expected that the subroutine will return the "HTML::Element"(s) which are "tr" element(s). The reason a subroutine might be preferred is in the case that the HTML designers gave you 8 sample "tr" rows but only one prototype row is needed. So you can write a subroutine, to splice out the 7 rows you don't need and leave the one sample row remaining so that this API call can clone it and supply it to the "tr_proc" and "td_proc" calls. Now, as we move through the table rows with table data, we need to do two different things on each table row: * get one row of data from the "table_data" via "tr_data" The default procedure assumes the "table_data" is an array reference and shifts a row off of it: sub { my ($self, $data) = @_; shift(@{$data}) ; } Your function MUST return undef when there is no more rows to lay out. * take the "tr" element and mutate it via "tr_proc" The default procedure simply makes the id of the table row unique: sub { my ($self, $tr, $tr_data, $row_count, $root_id) = @_; $tr->attr(id => sprintf "%s_%d", $root_id, $row_count); } Now that we have our row of data, we call "td_proc" so that it can take the data and the "td" cells in this "tr" and process them. This function *must* be supplied. Whither a Table with No Rows Often when a table has no rows, we want to display a message indicating this to the view. Use conditional processing to decide what to display:
No Data is Good Data
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SEE ALSO * HTML::Tree A perl package for creating and manipulating HTML trees * HTML::ElementTable An HTML::Tree - based module which allows for manipulation of HTML trees using cartesian coordinations. * HTML::Seamstress An HTML::Tree - based module inspired by XMLC (), allowing for dynamic HTML generation via tree rewriting. AUTHOR Terrence Brannon, COPYRIGHT AND LICENSE Copyright (C) 2004 by Terrence Brannon This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.4 or, at your option, any later version of Perl 5 you may have available.