Extension:DPL3/Parameters: Other parameters

Manual

Parameters

Other parameters

updaterules

updaterules

define a set of rules which are executed to perform an update on selected articles (bulk update or template value editing)

Syntax:

updaterules=
    rule;
    ...
    rule;

Where rule is one of the following:

• rules for batch update of articles

    replace pattern;
        by     replacement;
    before  pattern;
        insert text;
    after   pattern;
        insert text;

• rules for interactive update of articles

    template  template name;
    legend    legend article name;
    table     table format;
    editform  form parameters;
    action    form action;
    hidden    value;
    submit    submit button;
    commit    commit button;
    parameter parameter name;
        value     value;
        format    display format;
        tooltip   text;
        optional  value;
        afterparm parameter name;

• common rules

    summary edit summary text;
    exec    value;

The first group of rules is intended for batch updates of articles. A DPL query can select a group of articles and perform updates like inserting a piece of text at a certain position or changing text portions based on regular expressions.

The second group of rules is intended for interactive form-based editing of template values.

The third group of rules is common to both other groups and controls the update process.

The updaterules feature is intended for wiki expert users only. It is recommended that articles using this statement are 'protected':

Rules for batch update in detail:

replace pattern;

Defines a regular expression which matches text portions that shall be replaced. It is in the responsibility of the user to provide enclosing characters for the regexp; modifiers line 'U' or 'm' can be used.

by replacement;

Defines the replacement for the above pattern; back references like \1 can be used.

before pattern;

Defines locations where text will be inserted. The location(s) will be immediately before the match(es) of the pattern. If a pattern matches multiple times, multiple inserts will be performed.

The regexp will implicitly be enclosed in slashes. Hence literal slash characters must be escaped by backslashes.

after pattern;

Defines locations where text will be inserted. The location(s) will be immediately after the match(es) of the pattern. If a pattern matches multiple times, multiple inserts will be performed.

The regexp will implicitly be enclosed in slashes. Hence literal slash characters must be escaped by backslashes.

insert text;

Defines the text to be inserted.

A DPL statement may contain replacement, insertion before and after at the same time.

    replace /([a-z]+])-cat/;
    by      \1-dog;
    before  foo;
    insert  bar;
    after   foo;
    insert  bar2;

Only one 'replace'-'by' sequence, one insertion 'before' and one insertion 'after' can be specified. 'replace' is always executed first, followed by 'insert before' and 'insert after', regardless of the sequence in which the rules appear in the DPL source ´text.

Rules for interactive update in detail:

template template name;

The name of the template; the prefix "Template:" must be given.

be inserted. The location(s) will be immediately before the match(es) of the pattern. If a pattern matches multiple times, multiple inserts will be performed.

The regexp will implicitly be enclosed in slashes. Hence literal slash characters must be escaped by backslashes.

a regular expression

    after   pattern;
    insert  text;
    replace pattern;
    by      replacement;

For safety reasons the update statements will only be performed if "exec yes" is specified. So, leaving this away, you can check what would happen if the update were to be executed.

Note that if "exec yes" is present the update will be performed each time the page is rendered which contains the DPL statement with the updaterules. So it is advisable to set "exec yes" only via a command line argument and not as part of the statioc article text. Thus you stay in control when the update happens. Typically one would use an URL parameter like DPL_arg1 for that purpose.

The size of the form fields will dapt to the size of the displayed content.

text is plain text; replacement is text which may contain references (like \1) to the matching pattern (provided that this pattern contains match groups).

deleterules

deleterules

allow the mass deletion of wiki pages

deleterules=
    reason text;
    exec   true;

This command is experimental at the moment.

This will delete the selected pages; If "exec true" is missing, nothing will happen.

goal

goal	set the overall goal for DPL to either show pages (default) or categories these pages belong to

Syntax:

goal=pages | categories

Explanation:

Default is 'pages', which means that DPL produces a list of pages. And this is exactly what the name DPL promises.

If you set the goal parameter to 'categories' the list of pages will still be produced but you won't see it. Instead it will be used to calculate a unique ordered list of all categories these pages belong to.

This allows you to ask a question like: Given all pages that are member of category X with a title matching "y%" and which use template "Z": to which categories do these pages belong?

One of the more useful applications would be question like: "To which categories do the pages belong which contain a reference to the current page?"

The output of "goal=categories" is technically a list of pages of type category. This means that you can use all DPL formatting options (mode=userformat, listseparators, columns etc.) and pseudo variables (%TITLE%, %PAGE%) to customise the layout of your report.

Technical Note:

Due to some limitations in MySQL it is currently not possible to restrict the intermediate result set of pages to a certain maximum (using the LIMIT clause). In addition the generated SQL code is not in all cases optimal (as its structure provides for complex selection criteria and therefore is unnecessarily complex in simple cases). So be careful and apply precise selection criteria.

allowcachedresults

allowcachedresults

Cache query results to improve performance keep servers from crashing under high load.

Syntax:

allowcachedresults=true | false

Explanation:

Default: true All queries are cached by default to reduce server load as generally articles do not change often enough to require updating every page load. If immediate updates are required every page load then set this parameter to false. The cache period is handled by the #cacheperiod parameter.

This parameter has no effect on Fandom projects since cached results is always set to true to reduce server load. The default cacheperiod is quite short though: One hour instead of 14 days for a page without DPL. In the vast majority or cases this default can be increased by one or even two orders of magnitude.

reset

reset

suppress references to pages, templates, images, categories in DPL output

Syntax:

reset=keyword,.., where keyword is one of:

• categories
• templates
• images
• links
• all — a synonym for all of the above

The output of a DPL statement typically creates links to all pages which are part of the result set. The inclusion of contents from other pages via DPL (using 'include') normally has the consequence

• that the page containing the DPL query becomes part of the categories of the transcluded page
• that it shares ('adopts') their use of templates
• that it shares their references to images
• that it shares their references to other articles.

In some cases this may be useful. But in many cases this is not wanted. Especially when you use DPL to create a printable document which contains the full text of other articles you will probably not want to duplicate all links, template uses etc. of those articles.

The reset parameter will suppress all or some of the effects described above.

There are some subtle differences here depending on the mode in which you use DPL. These differences affect the question how links, and categories etc. are treated which are direct part of the document containing the DPL query. Example:

[[Category:Q Cat]] linking to [[Q Link]] and showing [[Image:Q Image]] and using {{Q Template}}
... DPL query which includes contents from other articles.
    assuming that this contents contains links and images, 
             that it uses templates and thatthe articles are part of one or more categories
    RESET statement at the end of the DPL query with one or more of 'categories,templates,images,links'
...

In parser extension mode (DPL tag like <DPL>):

reset=categories

will ignore categories of included contents but keep 'own' categories like 'Q Cat'.

reset=images

will throw away references to images contained in included contents but keep 'own' images like 'Q Image'.

reset=templates

will ignore templates used in included contents but keep 'own' template usage ('Q Template').

reset=links

will throw away all references to other pages, i.e. links contained in included contents and links like 'Q Link' will be ignored. This means that all links can be used in the normal "FORWARD" way, but no "BACKLINKS" are available for them.

If you want to avoid the above described effect of reset on your 'own' links you can use eliminate. But you should know that eliminate is rather expensive in terms of computer power as it does a second parse for all included contents.

In parser function mode ({{#DPL:....}}):

reset=categories

will ignore all categories

reset=images

will throw away all references to images

reset=templates

will ignore all template invocations

reset=links

will throw away all references to other pages

As you see, using reset in parser function mode will clear everything regardless whether it comes from included contents or whether it is direct part of the document containing the DPL query.

If you want to avoid the above described effect of reset, you can use eliminate. But you should know that eliminate is rather expensive in terms of computing power as it does a second parse for all included contents. The extra parser step is conducted as soon as you specify eliminate. In terms of extra processing needed it does not make a difference whether you specify one or more arguments for the 'eliminate' command.

If you have more than one DPL query in a document the effects will depend on the exact mode (parser extension or parser function mode), on the sequence of the statements and on the presence of 'reset' or 'eliminate' statements in each of the queries and on their individual arguments. As this is a very rare case we only give a simple rule of thumb here: Once you have used 'reset' in parser function mode or 'reset=links' in parser extension mode the effect of these statements will dominate the rest.

fixcategory

fixcategory

assign the article containing a DPL statement to a category although reset was used.

Syntax: fixcategory=category name

Use multiple commands to assign the article to more than one category.

If you use reset=all or reset=categories the article containing your DPL statement will not be recorded in the mediawiki link database. This may be quite useful if your article transcludes content from other pages. Without the reset command your article would appear in a category if you included a text portion containing an assignment to that category.

As a side effect of using reset=all your article will not appear in a category even if you literally assign it to one. The fixcategory allows you to make a category assignment which is not blocked by the reset command.

eliminate

eliminate

suppress references to pages, templates, images, categories in DPL output

Syntax:

eliminate=keyword,..

Where keyword is one of:

• categories
• templates
• images
• links
• all — a synonym for all of the above

The output of a DPL statement typically creates links to all pages which are part of the result set. The inclusion of contents from other pages via DPL (using include) normally has these consequences:

• the page containing the DPL query becomes part of the categories of the transcluded page
• shares ('adopts') their use of templates
• shares their references to images
• shares their references to other articles

In some cases this may be useful. But in many cases this is not wanted. Especially when you use DPL to create a printable document which contains the full text of other articles you will probably not want to duplicate all links, template uses etc. of those articles.

The eliminate parameter will suppress all or some of the effects described above.

For further explanation see reset.

Please note that the use of eliminate needs a considerable amount of extra computing power as it performs a second parser step for each included document.

debug

debug

Sets debugging level.

Syntax:

debug=n, where n is one of:

• 0 — Silent mode, shows nothing
• 1 — Quiet mode, shows (fatal) errors
• 2 — Default mode, like 1 + shows warnings; — (default)
• 3 — Verbose mode, like 2
• 4 — Dump raw SQL Query; only if $wgDebugDumpSql is set to true.
• 5 — Show wiki text output from DPL instead of parsed wiki text.

If you use debug param but not in first position in the DPL element, the new debug settings are not applied before all previous parameters have been parsed and checked. This will generate a warning for debug=2 and above.

Example:

{{#dpl:
 | namespace = Media
 | debug     = 0
 | namespace = Special
}}

This list will output the error for the first namespace: Media is not a valid namespace value (pseudo-namespace). Assuming you haven't changed the default debug value (2), you will also get a warning: debug=1 is not input first (before namespace=Media). So it did not apply to namespace=Media but only to what's after. Indeed, you won't get the warning for the second namespace (Special) since debug=0 changed debug settings to silent mode.

DPL debug messages are translatable in DynamicPageList2.i18n.php. See also #Internationalization.

'debug=1' will suppress warning messages (e.g. if the result set of a DPL query is empty). As an alternative, you can use the suppresserrors statement.

execandexit

execandexit

process the command given as an argument and then exit immediately.

Syntax:

execandexit=wiki text
or
execandexit=geturlargs

If no wiki text is given the command will be ignored. Otherwise DPL will output the wiki text and exit immediately. Note that the wiki text may be a parser function call which evaluates to an empty string.

The special word geturlargs can be used as a wiki text to transform URL arguments starting with DPL_ into variables which can then be accessed via #var (if the Variables extension is installed) or via #dplvar.

Purpose:

Using this command you can prevent DPL from executing a database query; this may be useful if a necessary parameter was not given by the user. Note that an #if function call would NOT help in that case because #if evaluates its complete content before taking the "if" or the "else" path. So, emebdding a DPL call within a #if is much less efficient than using the execandexit function.

A typical use would look like this (note the double pipe symbols within the #if. Calling the following page with &DPL_cat=Country would list countries, omitting the &cat parameter would trigger the error text message (without DPL going to the database):

{{#dpl:execandexit=geturlargs}}
{{#dpl: 
 | execandexit     = {{#if:{{#dplvar:DPL_cat}}||please specify a category via &DPL_cat= in the URL!}}
 | resultsheader   = pages in category {{#dplvar:DPL_cat}}:\n
 | noresultsheader = there are no pages in category {{#dplvar:DPL_cat}}.\n
 | count           = 5
 | category        = {{#dplvar:DPL_cat}}
}}

See also: Template:Extension DPL scroll and Scrolling

Note execandexit acts like a short-circuit evaluation. This means, for example, that successive statements to influence caching behaviour (like allowcachedresults) will not be interpreted.

cacheperiod

cacheperiod

define the expiration period for the dplcache

Syntax:

cacheperiod=number of seconds

The default is 3600 seconds which is one hour. By comparison, the default expiration period when DPL is not involved is 1,209,600 seconds on Fandom, or 14 days. The DPL cache gets invalidated (and the page rebuilt before cacheperiod ends) when the page that hosts the DPL query is edited or whenever a page already in the results is. On the other hand, if a page that is not part of the results gets edited and starts matching the DPL query, it will not be picked up until cacheperiod ends or something else invalidates the DPL cache.

So it is perfectly fine to set the cache to 14 days for DPL queries that aren't expected to grow their number of results quickly. In most other cases, a cache of 1 day (86,400 seconds) is probably good enough.

DPL is a resource-intensive tool. Longer cache periods reduce computing costs and greenhouse gas emissions. With that said, only the first person(s) to load a page containing a DPL query whose cache has expired or is invalidated will have to wait for Fandom servers to rebuild it.