>Anyway, I just wanted to list the thoughts. In none of these use cases is straight yaml or json the
>obvious answer. -- [[Will]]
->> Okie. I've had a play with this. A plugin is included inline below, but it is only a rough first pass to
+>> Okie. I've had a play with this. A 'form' plugin is included inline below, but it is only a rough first pass to
>> get a feel for the design space.
>>
>> The current design defines a new type of page - a 'form'. The type of page holds YAML data
\[[!inline pages="form_eq(age,15)" archive="yes"]]
>> will include a link to the page generated above.
->>
->> Anyway, here is the plugin. As noted above this is only a preliminary, exploratory, attempt. -- [[Will]]
+
+>>> Okie, I've just made another plugin to try and do things in a different way.
+>>> This approach adds a 'data' directive. There are two arguments, `key` and `value`.
+>>> The directive is replaced by the value. There is also a match function, which is similar
+>>> to the one above. It also takes two arguments, a key and a value. It returns true if the
+>>> page has that key/value pair in a data directive. e.g.:
+
+ \[[!data key="age" value="15"]]
+
+>>> then, in another page:
+
+ \[[!inline pages="data_eq(age,15)" archive="yes"]]
+
+>>> I expect that we could have more match functions for each type of structured data,
+>>> I just wanted to implement a rough prototype to get a feel for how it behaves. -- [[Will]]
+
+>> Anyway, here are the plugins. As noted above these are only preliminary, exploratory, attempts. -- [[Will]]
+
+>>>> I've just updated the second of the two patches below. The two patches are not mutually
+>>>> exclusive, but I'm leaning towards the second as more useful (for the things I'm doing). -- [[Will]]
+
+I think it's awesome that you're writing this code to explore the problem
+space, [[Will]] -- and these plugins are good stabs at at least part of it.
+Let me respond to a few of your comments.. --[[Joey]]
+
+On use cases, one use case is a user posting a bug report with structured
+data in it. A template is one way, but then the user has to deal with the
+format used to store the structured data. This is where a edit-time form
+becomes essential.
+
+> This was the idea with the 'form' plugin. With the 'data' plugin I was exploring
+> a different approach: try to keep the markup simple enough that the user can edit
+> the markup directly, and still have that be ok. I admit it is a stretch, but I thought
+> it worth exploring.
+
+Another use case is, after many such bugs have been filed,
+wanting to add a new field to each bug report. To avoid needing to edit
+every bug report it would be good if the fields in a bug report were
+defined somewhere else, so that just that one place can be edited to add
+the new field, and it will show up in each bug report (and in each bug
+report's edit page, as a new form field).
+
+> If I was going to do that, I'd use a perl script on a checked out
+> workspace. I think you're describing a rare operation and
+> so I'd be happy not having a web interface for it. Having said that,
+> if you just wanted to change the form for *new* pages, then you
+> can just edit the template used to create new pages.
+
+Re the form plugin, I'm uncomfortable with tying things into
+[[!cpan CGI::FormBuilder]] quite so tightly as you have.
+
+> Yeah :). But I wanted to explore the space and that was the
+> easiest way to start.
+
+CGI::FormBuilder
+could easily change in a way that broke whole wikis full of pages. Also,
+needing to sanitize FormBuilder fields with security implications is asking
+for trouble, since new FormBuilder features could add new fields, or
+add new features to existing fields (FormBuilder is very DWIM) that open
+new security holes.
+
+> There is a list of allowed fields. I only interpret those.
+
+I think that having a type system, that allows defining specific types,
+like "email address", by writing code (that in turn can use FormBuilder),
+is a better approach, since it should avoid becoming a security problem.
+
+> That would be possible. I think an extension to the 'data' plugin might
+> work here.
+
+One specific security hole, BTW, is that if you allow the `validate` field,
+FormBuilder will happily treat it as a regexp, and we don't want to expose
+arbitrary perl regexps, since they can at least DOS a system, and can
+probably be used to run arbitrary perl code.
+
+> I validate the validate field :). It only allows validate fields that match
+> `/^[\w\s]+$/`. This means you can really only use the pre-defined
+> validation types in FormBuilder.
+
+The data plugin only deals with a fairly small corner of the problem space,
+but I think does a nice job at what it does. And could probably be useful
+in a large number of other cases.
+
+> I think the data plugin is more likely to be useful than the form plugin.
+> I was thinking of extending the data directive by allowing an 'id' parameter.
+> When you have an id parameter, then you can display a small form for that
+> data element. The submission handler would look through the page source
+> for the data directive with the right id parameter and edit it. This would
+> make the data directive more like the current 'form' plugin.
+
+> That is making things significantly more complex for less significant gain though. --[[Will]]
+
+> Oh, one quick other note. The data plugin below was designed to handle multiple
+> data elements in a single directive. e.g.
+
+ \[[!data key="Depends on" link="bugs/bugA" link="bugs/bugB" value=6]]
+
+> would match `data_eq(Depends on,6)`, `data_link(Depends on,bugs/bugA)`, `data_link(Depends on,bugs/bugB)`
+> or, if you applied the patch in [[todo/tracking_bugs_with_dependencies]] then you can use 'defined pagespecs'
+> such as `data_link(Depends on,~openBugs)`. The ability to label links like this allows separation of
+> dependencies between bugs from arbitrary links.
+
+----
#!/usr/bin/perl
# Interpret YAML data to make a web form
} #}}}
1
+
+----
+
+ #!/usr/bin/perl
+ # Allow data embedded in a page to be checked for
+ package IkiWiki::Plugin::data;
+
+ use warnings;
+ use strict;
+ use IkiWiki 2.00;
+
+ my $inTable = 0;
+
+ sub import { #{{{
+ hook(type => "getsetup", id => "data", call => \&getsetup);
+ hook(type => "needsbuild", id => "data", call => \&needsbuild);
+ hook(type => "preprocess", id => "data", call => \&preprocess, scan => 1);
+ hook(type => "preprocess", id => "datatable", call => \&preprocess_table, scan => 1); # does this need scan?
+ } # }}}
+
+ sub getsetup () { #{{{
+ return
+ plugin => {
+ safe => 1,
+ rebuild => 1, # format plugin
+ },
+ } #}}}
+
+ sub needsbuild (@) { #{{{
+ my $needsbuild=shift;
+ foreach my $page (keys %pagestate) {
+ if (exists $pagestate{$page}{data}) {
+ if (exists $pagesources{$page} &&
+ grep { $_ eq $pagesources{$page} } @$needsbuild) {
+ # remove state, it will be re-added
+ # if the preprocessor directive is still
+ # there during the rebuild
+ delete $pagestate{$page}{data};
+ }
+ }
+ }
+ }
+
+ sub preprocess (@) { #{{{
+ my @argslist = @_;
+ my %params=@argslist;
+
+ my $html = '';
+ my $class = defined $params{class}
+ ? 'class="'.$params{class}.'"'
+ : '';
+
+ if ($inTable) {
+ $html = "<th $class >$params{key}:</th><td $class >";
+ } else {
+ $html = "<span $class >$params{key}:";
+ }
+
+ while (scalar(@argslist) > 1) {
+ my $type = shift @argslist;
+ my $data = shift @argslist;
+ if ($type eq 'link') {
+ # store links raw
+ $pagestate{$params{page}}{data}{$params{key}}{link}{$data} = 1;
+ my $link=IkiWiki::linkpage($data);
+ add_depends($params{page}, $link);
+ $html .= ' ' . htmllink($params{page}, $params{destpage}, $link);
+ } elsif ($type eq 'data') {
+ $data = IkiWiki::preprocess($params{page}, $params{destpage},
+ IkiWiki::filter($params{page}, $params{destpage}, $data));
+ $html .= ' ' . $data;
+ # store data after processing - allows pagecounts to be stored, etc.
+ $pagestate{$params{page}}{data}{$params{key}}{data}{$data} = 1;
+ }
+ }
+
+ if ($inTable) {
+ $html .= "</td>";
+ } else {
+ $html .= "</span>";
+ }
+
+ return $html;
+ } # }}}
+
+ sub preprocess_table (@) { #{{{
+ my %params=@_;
+
+ my @lines;
+ push @lines, defined $params{class}
+ ? "<table class=\"".$params{class}.'">'
+ : '<table>';
+
+ $inTable = 1;
+
+ foreach my $line (split(/\n/, $params{datalist})) {
+ push @lines, "<tr>" . IkiWiki::preprocess($params{page}, $params{destpage},
+ IkiWiki::filter($params{page}, $params{destpage}, $line)) . "</tr>";
+ }
+
+ $inTable = 0;
+
+ push @lines, '</table>';
+
+ return join("\n", @lines);
+ } #}}}
+
+ package IkiWiki::PageSpec;
+
+ sub match_data_eq ($$;@) { #{{{
+ my $page=shift;
+ my $argSet=shift;
+ my @args=split(/,/, $argSet);
+ my $key=shift @args;
+ my $value=shift @args;
+
+ if (! exists $IkiWiki::pagestate{$page}{data}) {
+ return IkiWiki::FailReason->new("page does not contain any data directives");
+ }
+
+ if (! exists $IkiWiki::pagestate{$page}{data}{$key}) {
+ return IkiWiki::FailReason->new("page does not contain data key '$key'");
+ }
+
+ if ($IkiWiki::pagestate{$page}{data}{$key}{data}{$value}) {
+ return IkiWiki::SuccessReason->new("value matches");
+ } else {
+ return IkiWiki::FailReason->new("value does not match");
+ }
+ } #}}}
+
+ sub match_data_link ($$;@) { #{{{
+ my $page=shift;
+ my $argSet=shift;
+ my @params=@_;
+ my @args=split(/,/, $argSet);
+ my $key=shift @args;
+ my $value=shift @args;
+
+ if (! exists $IkiWiki::pagestate{$page}{data}) {
+ return IkiWiki::FailReason->new("page $page does not contain any data directives and so cannot match a link");
+ }
+
+ if (! exists $IkiWiki::pagestate{$page}{data}{$key}) {
+ return IkiWiki::FailReason->new("page $page does not contain data key '$key'");
+ }
+
+ foreach my $link (keys %{ $IkiWiki::pagestate{$page}{data}{$key}{link} }) {
+ # print STDERR "Checking if $link matches glob $value\n";
+ if (match_glob($link, $value, @params)) {
+ return IkiWiki::SuccessReason->new("Data link on page $page with key $key matches glob $value: $link");
+ }
+ }
+
+ return IkiWiki::FailReason->new("No data link on page $page with key $key matches glob $value");
+ } #}}}
+
+ 1