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diff --git a/doc/plugins/contrib/field.mdwn b/doc/plugins/contrib/field.mdwn new file mode 100644 index 000000000..363d3a7eb --- /dev/null +++ b/doc/plugins/contrib/field.mdwn @@ -0,0 +1,219 @@ +[[!template id=plugin name=field author="[[rubykat]]"]] +[[!tag type/meta]] +[[!toc]] +## NAME + +IkiWiki::Plugin::field - front-end for per-page record fields. + +## SYNOPSIS + + # activate the plugin + add_plugins => [qw{goodstuff field ....}], + + # simple registration + field_register => [qw{meta}], + + # simple registration with priority + field_register => { + meta => 'last' + foo => 'DD' + }, + + # allow the config to be queried as a field + field_allow_config => 1, + + # flag certain fields as "tags" + field_tags => { + BookAuthor => '/books/authors', + BookGenre => '/books/genres', + MovieGenre => '/movies/genres', + } + +## DESCRIPTION + +This plugin is meant to be used in conjunction with other plugins +in order to provide a uniform interface to access per-page structured +data, where each page is treated like a record, and the structured data +are fields in that record. This can include the meta-data for that page, +such as the page title. + +Plugins can register a function which will return the value of a "field" for +a given page. This can be used in a few ways: + +* In page templates; all registered fields will be passed to the page template in the "pagetemplate" processing. +* In PageSpecs; the "field" function can be used to match the value of a field in a page. +* In SortSpecs; the "field" function can be used for sorting pages by the value of a field in a page. +* By other plugins, using the field_get_value function, to get the value of a field for a page, and do with it what they will. + +## CONFIGURATION OPTIONS + +The following options can be set in the ikiwiki setup file. + +**field_allow_config** + + field_allow_config => 1, + +Allow the $config hash to be queried like any other field; the +keys of the config hash are the field names with a prefix of "CONFIG-". + +**field_register** + + field_register => [qw{meta}], + + field_register => { + meta => 'last' + foo => 'DD' + }, + +A hash of plugin-IDs to register. The keys of the hash are the names of the +plugins, and the values of the hash give the order of lookup of the field +values. The order can be 'first', 'last', 'middle', or an explicit order +sequence between 'AA' and 'ZZ'. If the simpler type of registration is used, +then the order will be 'middle'. + +This assumes that the plugins in question store data in the %pagestatus hash +using the ID of that plugin, and thus the field values are looked for there. + +This is the simplest form of registration, but the advantage is that it +doesn't require the plugin to be modified in order for it to be +registered with the "field" plugin. + +**field_tags** + + field_tags => { + BookAuthor => '/books/authors', + BookGenre => '/books/genres', + MovieGenre => '/movies/genres', + } + +A hash of fields and their associated pages. This provides a faceted +tagging system. + +The way this works is that a given field-name will be associated with a given +page, and the values of that field will be linked to sub-pages of that page, +the same way that the \[[!tag ]] directive does. + +This also provides a field with the suffix of `-tagpage` which gives +the name of the page to which that field-value is linked. + +For example: + + BookGenre: SF + +will link to "/books/genres/SF", with a link-type of "bookgenre". + +If one was using a template, then the following template: + + Genre: <TMPL_VAR BOOKGENRE> + GenrePage: <TMPL_VAR BOOKGENRE-TAGPAGE> + GenreLink: \[[<TMPL_VAR BOOKGENRE-TAGPAGE>]] + +would give: + + Genre: SF + GenrePage: /books/genres/SF + GenreLink: <a href="/books/genres/SF/">SF</a> + +## PageSpec + +The `field` plugin provides a few PageSpec functions to match values +of fields for pages. + +* field + * **field(*name* *glob*)** + * field(bar Foo\*) will match if the "bar" field starts with "Foo". +* destfield + * **destfield(*name* *glob*)** + * as for "field" but matches against the destination page (i.e when the source page is being included in another page). +* field_item + * **field_item(*name* *glob*)** + * field_item(bar Foo) will match if one of the values of the "bar" field is "Foo". +* destfield_item + * **destfield_item(*name* *glob*)** + * as for "field_item" but matches against the destination page. +* field_null + * **field_null(*name*)** + * matches if the field is null, that is, if there is no value for that field, or the value is empty. +* field_tagged + * **field_tagged(*name* *glob*)** + * like `tagged`, but this uses the tag-bases and link-types defined in the `field_tags` configuration option. +* destfield_tagged + * **destfield_tagged(*name* *glob*)** + * as for "field_tagged" but matches against the destination page. + +## SortSpec + +The "field" SortSpec function can be used to sort a page depending on the value of a field for that page. This is used for directives that take sort parameters, such as **inline** or **report**. + +field(*name*) + +For example: + +sort="field(bar)" will sort by the value og the "bar" field. + +Additionally, the "field_natural" SortSpec function will use the +Sort::Naturally module to do its comparison (though it will fail if that +module is not installed). + +## FUNCTIONS + +### field_register + +field_register(id=>$id); + +Register a plugin as having field data. The above form is the simplest, where +the field value is looked up in the %pagestatus hash under the plugin-id. + +Additional Options: + +**call=>&myfunc** + +A reference to a function to call rather than just looking up the value in the +%pagestatus hash. It takes two arguments: the name of the field, and the name +of the page. It is expected to return (a) an array of the values of that field +if "wantarray" is true, or (b) a concatenation of the values of that field +if "wantarray" is not true, or (c) undef if there is no field by that name. + + sub myfunc ($$) { + my $field = shift; + my $page = shift; + + ... + + return (wantarray ? @values : $value); + } + +**first=>1** + +Set this to be called first in the sequence of calls looking for values. Since +the first found value is the one which is returned, ordering is significant. +This is equivalent to "order=>'first'". + +**last=>1** + +Set this to be called last in the sequence of calls looking for values. Since +the first found value is the one which is returned, ordering is significant. +This is equivalent to "order=>'last'". + +**order=>$order** + +Set the explicit ordering in the sequence of calls looking for values. Since +the first found value is the one which is returned, ordering is significant. + +The values allowed for this are "first", "last", "middle", or a two-character +ordering-sequence between 'AA' and 'ZZ'. + +### field_get_value($field, $page) + + my $value = field_get_value($field, $page); + + my $value = field_get_value($field, $page, foo=>'bar'); + +Returns the value of the field for that page, or undef if none is found. +It is also possible to override the value returned by passing in +a value of your own. + +## DOWNLOAD + +* browse at GitHub: <http://github.com/rubykat/ikiplugins/blob/master/IkiWiki/Plugin/field.pm> +* git repo at git://github.com/rubykat/ikiplugins.git |