5 HTML::Element::Library - HTML::Element convenience functions
9 use HTML::Element::Library;
10 use HTML::TreeBuilder;
14 This method provides API calls for common actions on trees when using
19 The test suite contains examples of each of these methods in a file
22 =head2 Positional Querying Methods
24 =head3 $elem->siblings
26 Return a list of all nodes under the same parent.
30 Return the index of C<$elem> into the array of siblings of which it is
31 a part. L<HTML::ElementSuper> calls this method C<addr> but I don't
32 think that is a descriptive name. And such naming is deceptively close
33 to the C<address> function of C<HTML::Element>. HOWEVER, in the
34 interest of backwards compatibility, both methods are available.
40 =head3 $elem->position()
42 Returns the coordinates of this element in the tree it inhabits. This
43 is accomplished by succesively calling addr() on ancestor elements
44 until either a) an element that does not support these methods is
45 found, or b) there are no more parents. The resulting list is the
46 n-dimensional coordinates of the element in the tree.
48 =head2 Element Decoration Methods
50 =head3 HTML::Element::Library::super_literal($text)
52 In L<HTML::Element>, Sean Burke discusses super-literals. They are
53 text which does not get escaped. Great for includng Javascript in
54 HTML. Also great for including foreign language into a document.
56 So, you basically toss C<super_literal> your text and back comes your
57 text wrapped in a C<~literal> element.
59 One of these days, I'll around to writing a nice C<EXPORT> section.
61 =head2 Tree Rewriting Methods
63 =head3 "de-prepping" HTML
65 Oftentimes, the HTML to be worked with will have multiple sample rows:
74 But, before you begin to rewrite the HTML with your model data, you
75 typically only want 1 or 2 sample rows.
77 Thus, you want to "crunch" the multiple sample rows to a specified
78 amount. Hence the C<crunch> method:
80 $tree->crunch(look_down => [ '_tag' => 'li' ], leave => 2) ;
82 The C<leave> argument defaults to 1 if not given. The call above would
83 "crunch" the above 4 sample rows to:
90 =head3 Simplifying calls to HTML::FillInForm
92 Since HTML::FillInForm gets and returns strings, using HTML::Element
93 instances becomes tedious:
95 1. Seamstress has an HTML tree that it wants the form filled in on
96 2. Seamstress converts this tree to a string
97 3. FillInForm parses the string into an HTML tree and then fills in the form
98 4. FillInForm converts the HTML tree to a string
99 5. Seamstress re-parses the HTML for additional processing
101 I've filed a bug about this:
102 L<https://rt.cpan.org/Ticket/Display.html?id=44105>
104 This function, fillinform, allows you to pass a tree to fillinform
105 (along with your data structure) and get back a tree:
107 my $new_tree = $html_tree->fillinform($data_structure);
109 =head3 Mapping a hashref to HTML elements
111 It is very common to get a hashref of data from some external source -
112 flat file, database, XML, etc. Therefore, it is important to have a
113 convenient way of mapping this data to HTML.
115 As it turns out, there are 3 ways to do this in
116 HTML::Element::Library. The most strict and structured way to do this
117 is with C<content_handler>. Two other methods, C<hashmap> and
118 C<datamap> require less manual mapping and may prove even more easy to
119 use in certain cases.
121 As is usual with Perl, a practical example is always best. So let's
122 take some sample HTML:
125 <span id="name">?</span>
126 <span id="email">?</span>
127 <span id="gender">?</span>
129 Now, let's say our data structure is this:
131 $ref = { email => 'jim@beam.com', gender => 'lots' } ;
133 And let's start with the most strict way to get what you want:
135 $tree->content_handler(email => $ref->{email} , gender => $ref->{gender}) ;
137 In this case, you manually state the mapping between id tags and
138 hashref keys and then C<content_handler> retrieves the hashref data
139 and pops it in the specified place.
141 Now let's look at the two (actually 2 and a half) other hash-mapping
144 $tree->hashmap(id => $ref);
146 Now, what this function does is super-destructive. It finds every
147 element in the tree with an attribute named id (since 'id' is a
148 parameter, it could find every element with some other attribute also)
149 and replaces the content of those elements with the hashref value.
151 So, in the case above, the
153 <span id="name">?</span>
157 <span id="name"></span>
159 (it would be blank) - because there is nothing in the hash with that
160 value, so it substituted
164 which was blank and emptied the contents.
166 Now, let's assume we want to protect name from being auto-assigned.
169 $tree->hashmap(id => $ref, ['name']);
171 That last array ref is an exclusion list.
173 But wouldnt it be nice if you could do a hashmap, but only assigned
174 things which are defined in the hashref? C<< defmap() >> to the
177 $tree->defmap(id => $ref);
181 <span id="name">?</span>
185 =head4 $elem->hashmap($attr_name, \%hashref, \@excluded, $debug)
187 This method is designed to take a hashref and populate a series of
188 elements. For example:
191 <tr sclass="tr" class="alt" align="left" valign="top">
192 <td smap="people_id">1</td>
193 <td smap="phone">(877) 255-3239</td>
194 <td smap="password">*********</td>
198 In the table above, there are several attributes named C<< smap >>. If
199 we have a hashref whose keys are the same:
201 my %data = (people_id => 888, phone => '444-4444', password => 'dont-you-dare-render');
203 Then a single API call allows us to populate the HTML while excluding
206 $tree->hashmap(smap => \%data, ['password']);
208 Note: the other way to prevent rendering some of the hash mapping is
209 to not give that element the attr you plan to use for hash mapping.
211 Also note: the function C<< hashmap >> has a simple easy-to-type API.
212 Interally, it calls C<< hash_map >> (which has a more verbose keyword
213 calling API). Thus, the above call to C<hashmap()> results in this
216 $tree->hash_map(hash => \%data, to_attr => 'sid', excluding => ['password']);
218 =head4 $elem->defmap($attr_name, \%hashref, $debug)
220 C<defmap> was described above.
222 =head3 $elem->replace_content(@new_elem)
224 Replaces all of C<$elem>'s content with C<@new_elem>.
226 =head3 $elem->wrap_content($wrapper_element)
228 Wraps the existing content in the provided element. If the provided
229 element happens to be a non-element, a push_content is performed
232 =head3 $elem->set_child_content(@look_down, $content)
234 This method looks down $tree using the criteria specified in
235 @look_down using the the HTML::Element look_down() method.
237 After finding the node, it detaches the node's content and pushes
238 $content as the node's content.
240 =head3 $tree->content_handler(%id_content)
242 This is a convenience method. Because the look_down criteria will
249 <a id=fixme href=http://www.somesite.org>replace_content</a>
251 You can call this method to shorten your typing a bit. You can simply
254 $elem->content_handler( fixme => 'new text' )
258 $elem->set_child_content(sid => 'fixme', 'new text')
260 ALSO NOTE: you can pass a hash whose keys are C<id>s and whose values
261 are the content you want there and it will perform the replacement on
264 my %id_content = (name => "Terrence Brannon",
265 email => 'tbrannon@in.com',
267 content => $main_content);
268 $tree->content_handler(%id_content);
270 =head3 $tree->highlander($subtree_span_id, $conditionals, @conditionals_args)
272 This allows for "if-then-else" style processing. Highlander was a
273 movie in which only one would survive. Well, in terms of a tree when
274 looking at a structure that you want to process in C<if-then-else>
275 style, only one child will survive. For example, given this HTML
278 <span klass="highlander" id="age_dialog">
280 Hello, does your mother know you're
281 using her AOL account?
284 Sorry, you're not old enough to enter
285 (and too dumb to lie about your age)
292 We only want one child of the C<span> tag with id C<age_dialog> to
293 remain based on the age of the person visiting the page.
295 So, let's setup a call that will prune the subtree as a function of
300 my $tree = HTML::TreeBuilder->new_from_file('t/html/highlander.html');
305 under10 => sub { $_[0] < 10},
306 under18 => sub { $_[0] < 18},
312 And there we have it. If the age is less than 10, then the node with
313 id C<under10> remains. For age less than 18, the node with id
314 C<under18> remains. Otherwise our "else" condition fires and the child
315 with id C<welcome> remains.
317 =head3 $tree->passover(@id_of_element)
319 In some cases, you know exactly which element(s) should survive. In
320 this case, you can simply call C<passover> to remove it's (their)
321 siblings. For the HTML above, you could delete C<under10> and
322 C<welcome> by simply calling:
324 $tree->passover('under18');
326 Because passover takes an array, you can specify several children to
329 =head3 $tree->highlander2($tree, $conditionals, @conditionals_args)
331 Right around the same time that C<table2()> came into being,
332 Seamstress began to tackle tougher and tougher processing problems. It
333 became clear that a more powerful highlander was needed... one that
334 not only snipped the tree of the nodes that should not survive, but
335 one that allows for post-processing of the survivor node. And one that
336 was more flexible with how to find the nodes to snip.
338 Thus (drum roll) C<highlander2()>.
340 So let's look at our HTML which requires post-selection processing:
342 <span klass="highlander" id="age_dialog">
344 Hello, little <span id=age>AGE</span>-year old,
345 does your mother know you're using her AOL account?
348 Sorry, you're only <span id=age>AGE</span>
349 (and too dumb to lie about your age)
352 Welcome, isn't it good to be <span id=age>AGE</span> years old?
356 In this case, a branch survives, but it has dummy data in it. We must
357 take the surviving segment of HTML and rewrite the age C<span> with
358 the age. Here is how we use C<highlander2()> to do so:
363 $branch->look_down(id => 'age')->replace_content($age);
366 my $if_then = $tree->look_down(id => 'age_dialog');
368 $if_then->highlander2(
386 We pass it the tree (C<$if_then>), an arrayref of conditions (C<cond>)
387 and an arrayref of arguments which are passed to the C<cond>s and to
388 the replacement subs.
390 The C<under10>, C<under18> and C<welcome> are id attributes in the
391 tree of the siblings of which only one will survive. However, should
392 you need to do more complex look-downs to find the survivor, then
393 supply an array ref instead of a simple scalar:
395 $if_then->highlander2(
397 [class => 'r12'] => [
401 [class => 'z22'] => [
405 [class => 'w88'] => [
413 =head3 $tree->overwrite_attr($mutation_attr => $mutating_closures)
415 This method is designed for taking a tree and reworking a set of nodes
416 in a stereotyped fashion. For instance let's say you have 3 remote
417 image archives, but you don't want to put long URLs in your img src
418 tags for reasons of abstraction, re-use and brevity. So instead you do
421 <img src="/img/smiley-face.jpg" fixup="src lnc">
422 <img src="/img/hot-babe.jpg" fixup="src playboy">
423 <img src="/img/footer.jpg" fixup="src foobar">
425 and then when the tree of HTML is being processed, you make this call:
428 lnc => sub { my ($tree, $mute_node, $attr_value)= @_; "http://lnc.usc.edu$attr_value" },
429 playboy => sub { my ($tree, $mute_node, $attr_value)= @_; "http://playboy.com$attr_value" }
430 foobar => sub { my ($tree, $mute_node, $attr_value)= @_; "http://foobar.info$attr_value" }
433 $tree->overwrite_attr(fixup => \%closures) ;
435 and the tags come out modified like so:
437 <img src="http://lnc.usc.edu/img/smiley-face.jpg" fixup="src lnc">
438 <img src="http://playboy.com/img/hot-babe.jpg" fixup="src playboy">
439 <img src="http://foobar.info/img/footer.jpg" fixup="src foobar">
441 =head3 $tree->mute_elem($mutation_attr => $mutating_closures, [ $post_hook ] )
443 This is a generalization of C<overwrite_attr>. C<overwrite_attr>
444 assumes the return value of the closure is supposed overwrite an
445 attribute value and does it for you. C<mute_elem> is a more general
446 function which does nothing but hand the closure the element and let
447 it mutate it as it jolly well pleases :)
449 In fact, here is the implementation of C<overwrite_attr> to give you a
450 taste of how C<mute_attr> is used:
452 sub overwrite_action {
453 my ($mute_node, %X) = @_;
455 $mute_node->attr($X{local_attr}{name} => $X{local_attr}{value}{new});
459 sub HTML::Element::overwrite_attr {
462 $tree->mute_elem(@_, \&overwrite_action);
465 =head2 Tree-Building Methods
467 =head3 Unrolling an array via a single sample element (<ul> container)
469 This is best described by example. Given this HTML:
471 <strong>Here are the things I need from the store:</strong>
473 <li class="store_items">Sample item</li>
476 We can unroll it like so:
478 my $li = $tree->look_down(class => 'store_items');
480 my @items = qw(bread butter vodka);
482 $tree->iter($li => @items);
488 <body>Here are the things I need from the store:
490 <li class="store_items">bread</li>
491 <li class="store_items">butter</li>
492 <li class="store_items">vodka</li>
497 Now, you might be wondering why the API call is:
499 $tree->iter($li => @items)
505 and there is no good answer. The latter would be more concise and it
506 is what I should have done.
508 =head3 Unrolling an array via n sample elements (<dl> container)
510 C<iter()> was fine for awhile, but some things (e.g. definition lists)
511 need a more general function to make them easy to do. Hence
512 C<iter2()>. This function will be explained by example of unrolling a
513 simple definition list.
515 So here's our mock-up HTML from the designer:
517 <dl class="dual_iter" id="service_plan">
519 <dd>A person who draws blood.</dd>
522 <dd>A clone of Iggy Pop.</dd>
525 <dd>A relative of Edgar Allan Poe.</dd>
527 <dt class="adstyle">sample header</dt>
528 <dd class="adstyle2">sample data</dd>
532 And we want to unroll our data set:
535 ['the pros' => 'never have to worry about service again'],
536 ['the cons' => 'upfront extra charge on purchase'],
537 ['our choice' => 'go with the extended service plan']
541 Now, let's make this problem a bit harder to show off the power of
542 C<iter2()>. Let's assume that we want only the last <dt> and it's
543 accompanying <dd> (the one with "sample data") to be used as the
544 sample data for unrolling with our data set. Let's further assume that
545 we want them to remain in the final output.
547 So now, the API to C<iter2()> will be discussed and we will explain
548 how our goal of getting our data into HTML fits into the API.
554 This is how to look down and find the container of all the elements we
555 will be unrolling. The <dl> tag is the container for the dt and dd
556 tags we will be unrolling.
558 If you pass an anonymous subroutine, then it is presumed that
559 execution of this subroutine will return the HTML::Element
560 representing the container tag. If you pass an array ref, then this
561 will be dereferenced and passed to C<HTML::Element::look_down()>.
563 default value: C<< ['_tag' => 'dl'] >>
565 Based on the mock HTML above, this default is fine for finding our
566 container tag. So let's move on.
570 This is an array reference of data that we will be putting into the
571 container. You must supply this. C<@items> above is our
576 After we find the container via C<wrapper_ld>, we may want to
577 pre-process some aspect of this tree. In our case the first two sets
578 of dt and dd need to be removed, leaving the last dt and dd. So, we
579 supply a C<wrapper_proc> which will do this.
585 This anonymous subroutine returns an array ref of C<HTML::Element>s
586 that will be cloned and populated with item data (item data is a "row"
589 default: returns an arrayref consisting of the dt and dd element
590 inside the container.
594 This is a subroutine that takes C<wrapper_data> and retrieves one
595 "row" to be "pasted" into the array ref of C<HTML::Element>s found via
596 C<item_ld>. I hope that makes sense.
598 default: shifts C<wrapper_data>.
602 This is a subroutine that takes the C<item_data> and the
603 C<HTML::Element>s found via C<item_ld> and produces an arrayref of
604 C<HTML::Element>s which will eventually be spliced into the container.
606 Note that this subroutine MUST return the new items. This is done So
607 that more items than were passed in can be returned. This is useful
608 when, for example, you must return 2 dts for an input data item. And
609 when would you do this? When a single term has multiple spellings for
612 default: expects C<item_data> to be an arrayref of two elements and
613 C<item_elems> to be an arrayref of two C<HTML::Element>s. It replaces
614 the content of the C<HTML::Element>s with the C<item_data>.
618 After building up an array of C<@item_elems>, the subroutine passed as
619 C<splice> will be given the parent container HTML::Element and the
620 C<@item_elems>. How the C<@item_elems> end up in the container is up
621 to this routine: it could put half of them in. It could unshift them
624 default: C<< $container->splice_content(0, 2, @item_elems) >> In other
625 words, kill the 2 sample elements with the newly generated @item_elems
629 So now that we have documented the API, let's see the call we need:
632 # default wrapper_ld ok.
633 wrapper_data => \@items,
634 wrapper_proc => sub {
635 my ($container) = @_;
637 # only keep the last 2 dts and dds
638 my @content_list = $container->content_list;
639 $container->splice_content(0, @content_list - 2);
642 # default item_ld is fine.
643 # default item_data is fine.
644 # default item_proc is fine.
646 my ($container, @item_elems) = @_;
647 $container->unshift_content(@item_elems);
652 =head3 Select Unrolling
654 The C<unroll_select> method has this API:
656 $tree->unroll_select(
657 select_label => $id_label,
658 option_value => $closure, # how to get option value from data row
659 option_content => $closure, # how to get option content from data row
660 option_selected => $closure, # boolean to decide if SELECTED
661 data => $data # the data to be put into the SELECT
662 data_iter => $closure # the thing that will get a row of data
664 append => $boolean, # remove the sample <OPTION> data or append?
669 $tree->unroll_select(
670 select_label => 'clan_list',
671 option_value => sub { my $row = shift; $row->clan_id },
672 option_content => sub { my $row = shift; $row->clan_name },
673 option_selected => sub { my $row = shift; $row->selected },
674 data => \@query_results,
675 data_iter => sub { my $data = shift; $data->next },
680 =head2 Tree-Building Methods: Table Generation
682 Matthew Sisk has a much more intuitive (imperative) way to generate
683 tables via his module L<HTML::ElementTable|HTML::ElementTable>.
685 However, for those with callback fever, the following method is
686 available. First, we look at a nuts and bolts way to build a table
687 using only standard L<HTML::Tree> API calls. Then the C<table> method
688 available here is discussed.
692 package Simple::Class;
696 my @name = qw(bob bill brian babette bobo bix);
697 my @age = qw(99 12 44 52 12 43);
698 my @weight = qw(99 52 80 124 120 230);
703 bless {}, ref($this) || $this;
711 age => $age[rand $#age] + int rand 20,
713 weight => $weight[rand $#weight] + int rand 40
717 Set::Array->new(@data);
724 my $data = Simple::Class->load_data;
725 ++$_->{age} for @$data
727 =head3 Inline Code to Unroll a Table
732 <table id="load_data">
733 <tr> <th>name</th><th>age</th><th>weight</th> </tr>
735 <td id="name"> NATURE BOY RIC FLAIR </td>
736 <td id="age"> 35 </td>
737 <td id="weight"> 220 </td>
743 =head4 The manual way (*NOT* recommended)
745 require 'simple-class.pl';
746 use HTML::Seamstress;
749 my $seamstress = HTML::Seamstress->new_from_file('simple.html');
752 my $o = Simple::Class->new;
753 my $data = $o->load_data;
755 # find the <table> and <tr>
756 my $table_node = $seamstress->look_down('id', 'load_data');
757 my $iter_node = $table_node->look_down('id', 'iterate');
758 my $table_parent = $table_node->parent;
761 # drop the sample <table> and <tr> from the HTML
762 # only add them in if there is data in the model
763 # this is achieved via the $add_table flag
769 # Get a row of model data
770 while (my $row = shift @$data) {
772 # We got row data. Set the flag indicating ok to hook the table into the HTML
775 # clone the sample <tr>
776 my $new_iter_node = $iter_node->clone;
778 # find the tags labeled name age and weight and
779 # set their content to the row data
780 $new_iter_node->content_handler($_ => $row->{$_})
781 for qw(name age weight);
783 $table_node->push_content($new_iter_node);
787 # reattach the table to the HTML tree if we loaded data into some table rows
789 $table_parent->push_content($table_node) if $add_table;
791 print $seamstress->as_HTML;
793 =head3 $tree->table() : API call to Unroll a Table
795 require 'simple-class.pl';
796 use HTML::Seamstress;
799 my $seamstress = HTML::Seamstress->new_from_file('simple.html');
801 my $o = Simple::Class->new;
805 # tell seamstress where to find the table, via the method call
806 # ->look_down('id', $gi_table). Seamstress detaches the table from the
807 # HTML tree automatically if no table rows can be built
809 gi_table => 'load_data',
811 # tell seamstress where to find the tr. This is a bit useless as
812 # the <tr> usually can be found as the first child of the parent
816 # the model data to be pushed into the table
818 table_data => $o->load_data,
820 # the way to take the model data and obtain one row
821 # if the table data were a hashref, we would do:
822 # my $key = (keys %$data)[0]; my $val = $data->{$key}; delete $data->{$key}
825 my ($self, $data) = @_;
829 # the way to take a row of data and fill the <td> tags
832 my ($tr_node, $tr_data) = @_;
833 $tr_node->content_handler($_ => $tr_data->{$_})
834 for qw(name age weight)
838 print $seamstress->as_HTML;
840 =head4 Looping over Multiple Sample Rows
845 <table id="load_data" CELLPADDING=8 BORDER=2>
846 <tr> <th>name</th><th>age</th><th>weight</th> </tr>
847 <tr id="iterate1" BGCOLOR="white" >
848 <td id="name"> NATURE BOY RIC FLAIR </td>
849 <td id="age"> 35 </td>
850 <td id="weight"> 220 </td>
852 <tr id="iterate2" BGCOLOR="#CCCC99">
853 <td id="name"> NATURE BOY RIC FLAIR </td>
854 <td id="age"> 35 </td>
855 <td id="weight"> 220 </td>
860 * Only one change to last API call.
868 gi_tr => ['iterate1', 'iterate2']
870 =head3 $tree->table2() : New API Call to Unroll a Table
872 After 2 or 3 years with C<table()>, I began to develop production
873 websites with it and decided it needed a cleaner interface,
874 particularly in the area of handling the fact that C<id> tags will be
875 the same after cloning a table row.
877 First, I will give a dry listing of the function's argument
878 parameters. This will not be educational most likely. A better way to
879 understand how to use the function is to read through the incremental
880 unrolling of the function's interface given in conversational style
881 after the dry listing. But take your pick. It's the same information
882 given in two different ways.
884 =head4 Dry/technical parameter documentation
886 C<< $tree->table2(%param) >> takes the following arguments:
890 =item * C<< table_ld => $look_down >> : optional
892 How to find the C<table> element in C<$tree>. If C<$look_down> is an
893 arrayref, then use C<look_down>. If it is a CODE ref, then call it,
896 Defaults to C<< ['_tag' => 'table'] >> if not passed in.
898 =item * C<< table_data => $tabular_data >> : required
900 The data to fill the table with. I<Must> be passed in.
902 =item * C<< table_proc => $code_ref >> : not implemented
904 A subroutine to do something to the table once it is found. Not
905 currently implemented. Not obviously necessary. Just created because
906 there is a C<tr_proc> and C<td_proc>.
908 =item * C<< tr_ld => $look_down >> : optional
910 Same as C<table_ld> but for finding the table row elements. Please
911 note that the C<tr_ld> is done on the table node that was found
912 I<instead> of the whole HTML tree. This makes sense. The C<tr>s that
913 you want exist below the table that was just found.
915 Defaults to C<< ['_tag' => 'tr'] >> if not passed in.
917 =item * C<< tr_data => $code_ref >> : optional
919 How to take the C<table_data> and return a row. Defaults to:
921 sub { my ($self, $data) = @_;
925 =item * C<< tr_proc => $code_ref >> : optional
927 Something to do to the table row we are about to add to the table we
928 are making. Defaults to a routine which makes the C<id> attribute
932 my ($self, $tr, $tr_data, $tr_base_id, $row_count) = @_;
933 $tr->attr(id => sprintf "%s_%d", $tr_base_id, $row_count);
936 =item * C<< td_proc => $code_ref >> : required
938 This coderef will take the row of data and operate on the C<td> cells
939 that are children of the C<tr>. See C<t/table2.t> for several usage
945 my ($tr, $data) = @_;
946 my @td = $tr->look_down('_tag' => 'td');
947 for my $i (0..$#td) {
948 $td[$i]->splice_content(0, 1, $data->[$i]);
954 =head4 Conversational parameter documentation
956 The first thing you need is a table. So we need a look down for that.
957 If you don't give one, it defaults to
961 What good is a table to display in without data to display?! So you
962 must supply a scalar representing your tabular data source. This
963 scalar might be an array reference, a C<next>able iterator, a DBI
964 statement handle. Whatever it is, it can be iterated through to build
965 up rows of table data. These two required fields (the way to find the
966 table and the data to display in the table) are C<table_ld> and
967 C<table_data> respectively. A little more on C<table_ld>. If this
968 happens to be a CODE ref, then execution of the code ref is presumed
969 to return the C<HTML::Element> representing the table in the HTML
972 Next, we get the row or rows which serve as sample C<tr> elements by
973 doing a C<look_down> from the C<table_elem>. While normally one sample
974 row is enough to unroll a table, consider when you have alternating
975 table rows. This API call would need one of each row so that it can
976 cycle through the sample rows as it loops through the data.
977 Alternatively, you could always just use one row and make the
978 necessary changes to the single C<tr> row by mutating the element in
979 C<tr_proc>, discussed below. The default C<tr_ld> is C<< ['_tag' =>
980 'tr'] >> but you can overwrite it. Note well, if you overwrite it with
981 a subroutine, then it is expected that the subroutine will return the
982 C<HTML::Element>(s) which are C<tr> element(s). The reason a
983 subroutine might be preferred is in the case that the HTML designers
984 gave you 8 sample C<tr> rows but only one prototype row is needed. So
985 you can write a subroutine, to splice out the 7 rows you don't need
986 and leave the one sample row remaining so that this API call can clone
987 it and supply it to the C<tr_proc> and C<td_proc> calls.
989 Now, as we move through the table rows with table data, we need to do
990 two different things on each table row:
994 =item * get one row of data from the C<table_data> via C<tr_data>
996 The default procedure assumes the C<table_data> is an array reference
997 and shifts a row off of it:
1000 my ($self, $data) = @_;
1004 Your function MUST return undef when there is no more rows to lay out.
1006 =item * take the C<tr> element and mutate it via C<tr_proc>
1008 The default procedure simply makes the id of the table row unique:
1011 my ($self, $tr, $tr_data, $row_count, $root_id) = @_;
1012 $tr->attr(id => sprintf "%s_%d", $root_id, $row_count);
1017 Now that we have our row of data, we call C<td_proc> so that it can
1018 take the data and the C<td> cells in this C<tr> and process them. This
1019 function I<must> be supplied.
1021 =head3 Whither a Table with No Rows
1023 Often when a table has no rows, we want to display a message
1024 indicating this to the view. Use conditional processing to decide what
1028 <table><tr><td>No Data is Good Data</td></tr></table>
1032 <table id="load_data">
1033 <tr> <th>name</th><th>age</th><th>weight</th> </tr>
1035 <td id="name"> NATURE BOY RIC FLAIR </td>
1036 <td id="age"> 35 </td>
1037 <td id="weight"> 220 </td>
1043 =head2 Tree-Killing Methods
1047 This removes any nodes from the tree which consist of nothing or
1048 nothing but whitespace. See also delete_ignorable_whitespace in
1051 =head2 Loltree Functions
1053 A loltree is an arrayref consisting of arrayrefs which is used by C<<
1054 new_from__lol >> in L<HTML::Element> to produce HTML trees. The CPAN
1055 distro L<XML::Element::Tolol> creates such XML trees by parsing XML
1056 files, analagous to L<XML::Toolkit>. The purpose of the functions in
1057 this section is to allow you manipulate a loltree programmatically.
1059 These could not be methods because if you bless a loltree, then
1060 HTML::Tree will barf.
1062 =head3 HTML::Element::newchild($lol, $parent_label, @newchild)
1064 Given this initial loltree:
1066 my $initial_lol = [ note => [ shopping => [ item => 'sample' ] ] ];
1070 sub shopping_items {
1071 my @shopping_items = map { [ item => _ ] } qw(bread butter beans);
1075 my $new_lol = HTML::Element::newnode($initial_lol, item => shopping_items());
1077 will replace the single sample with a list of shopping items:
1099 Thanks to kcott and the other Perlmonks in this thread:
1100 http://www.perlmonks.org/?node_id=912416
1105 =head2 L<HTML::Tree>
1107 A perl package for creating and manipulating HTML trees.
1109 =head2 L<HTML::ElementTable>
1111 An L<HTML::Tree> - based module which allows for manipulation of HTML
1112 trees using cartesian coordinations.
1114 =head2 L<HTML::Seamstress>
1116 An L<HTML::Tree> - based module inspired by XMLC
1117 (L<http://xmlc.enhydra.org>), allowing for dynamic HTML generation via
1120 =head2 Push-style templating systems
1122 A comprehensive cross-language
1123 L<list of push-style templating systems|http://perlmonks.org/?node_id=674225>.
1131 currently the API expects the subtrees to survive or be pruned to be
1134 $if_then->highlander2([
1135 under10 => sub { $_[0] < 10} ,
1136 under18 => sub { $_[0] < 18} ,
1141 $branch->look_down(id => 'age')->replace_content($age);
1146 but, it should be more flexible. the C<under10>, and C<under18> are
1147 expected to be ids in the tree... but it is not hard to have a check
1148 to see if this field is an array reference and if it, then to do a
1151 $if_then->highlander2([
1152 [class => 'under10'] => sub { $_[0] < 10} ,
1153 [class => 'under18'] => sub { $_[0] < 18} ,
1154 [class => 'welcome'] => [
1158 $branch->look_down(id => 'age')->replace_content($age);
1163 =head1 AUTHOR and ACKS
1165 Terrence Brannon, E<lt>tbone@cpan.orgE<gt>
1167 I appreciate the feedback from M. David Moussa Leo Keita regarding
1168 some issues with the test suite, namely (1) CRLF leading to test
1169 breakage in F<t/crunch.t> and (2) using the wrong module in
1170 F<t/prune.t> thus not having the right functionality available.
1172 Many thanks to BARBIE for his RT bug report.
1174 Many thanks to perlmonk kcott for his work on array rewriting:
1175 L<http://www.perlmonks.org/?node_id=912416>. It was crucial in the
1176 development of newchild.
1180 The source is at L<http://github.com/metaperl/html-element-library/tree/master>
1182 =head1 COPYRIGHT AND LICENSE
1184 Copyright (C) 2004 by Terrence Brannon
1186 This library is free software; you can redistribute it and/or modify
1187 it under the same terms as Perl itself, either Perl version 5.8.4 or,
1188 at your option, any later version of Perl 5 you may have available.