Scientific Guy at 15:35, 8 October 2022

2022-10-08T15:35:20Z

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	Default: true		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.		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.-->

	==reset==		==reset==

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{{DPL manual|section=Parameters|subsection=Other parameters|sort=P5}}
{{TOC right}}
==updaterules==
{{DPL parameter
|name = updaterules
|purpose= 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 <code>updaterules</code> feature is intended for wiki expert users only. It is recommended that articles usind 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 <code>updaterules</code>. 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==
{{DPL parameter
|name = deleterules
|purpose= 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==
{{DPL parameter
|name = goal
|purpose= set the overall goal for DPL to either show '''pages''' (default) or '''categories''' these pages belong to
}}

Syntax:

<code>goal=pages | categories</code>

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==
{{DPL parameter
|name = allowcachedresults
|purpose= Cache query results to improve performance keep servers from crashing under high load.
}}

Syntax:

<code>allowcachedresults=true | false</code>

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.

==reset==
{{DPL parameter
|name = reset
|purpose= suppress references to pages, templates, images, categories in DPL output
}}

Syntax:

<code>reset=keyword,..</code>, 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 <code>reset</code> 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:
<pre><nowiki>
[[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'
...
</nowiki></pre>

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 <code>reset</code> on your 'own' links you can use {{DPL|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 ('''<nowiki>{{#DPL:....}}</nowiki>'''):

;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 <code>reset</code> 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 <code>reset</code>, you can use {{DPL|eliminate}}</code>. 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 <code>eliminate</code>. 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==
{{DPL parameter
|name = fixcategory
|purpose= assign the article containing a DPL statement to a category although <code>reset</code> was used.
}}

Syntax:
<code>fixcategory=category name</code>

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

If you use <code>reset=all</code> or <code>reset=categories</code> 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 <code>reset</code> 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 <code>reset=all</code> your article will not appear in a category even if you literally assign it to one.
The <code>fixcategory</code> allows you to make a category assignment which is not blocked by the {{DPL|reset}} command.

==eliminate==
{{DPL parameter
|name = eliminate
|purpose= suppress references to pages, templates, images, categories in DPL output
}}

Syntax:

<code>eliminate=keyword,..</code>

Where <code>keyword</code> is one of:

* <code>categories</code>
* <code>templates</code>
* <code>images</code>
* <code>links</code>
* <code>all</code> — 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 {{DPL|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 <code>eliminate</code> parameter will suppress all or some of the effects described above.

For further explanation see {{DPL|reset}}.

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

==debug==
{{DPL parameter
|name = debug
|purpose= Sets debugging level.
}}

Syntax:

<code>debug=n</code>, 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 <code>debug=2</code> and above.

Example:

<pre><nowiki>
{{#dpl:
| namespace = Media
| debug = 0
| namespace = Special
}}
</nowiki></pre>

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

DPL debug messages are translatable in <code>DynamicPageList2.i18n.php</code>.

'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 {{DPL|suppresserrors}} statement.

==execandexit==
{{DPL parameter
|name = execandexit
|purpose= process the command given as an argument and then exit immediately.
}}

Syntax:

<code>execandexit=wiki text</code>
 or 
<code>execandexit=geturlargs</code>

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 <code>DPL_</code> 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):
<pre><nowiki>
{{#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}}
}}
</nowiki></pre>

See also: {{DPL|Scrolling}}

Note <code>execandexit</code> acts like a short-circuit evaluation. This means, for example, that successive statements to influence caching behaviour (like {{DPL|allowcachedresults}}) will not be interpreted.

==cacheperiod==
{{DPL parameter
|name = cacheperiod
|purpose= define the expiration period for the dplcache
}}

Syntax:

<code>cacheperiod=number of seconds</code>

The default is 3600 seconds which is one hour.

Help:DPL/Parameters: Other parameters - Revision history

Scientific Guy at 15:35, 8 October 2022

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