View source for Help:Conditional tables

{{Table help}}
{{Wikipedia how to|WP:CTB}}

There are three ways to conditionally display or hide rows within a table. All of the methods involve the use of parser conditionals, in particular, the parser {{kbd|#if}} statement (see the [[#Refresher on parser functions|§&nbsp;Refresher]] section) to conditionally include or exclude a row, depending on the value of some expression.

==Methods==

===CSS display:none property ===

The simplest option is to use the conditional with the CSS "{{kbd|display:none}}" property:

<syntaxhighlight lang="wikitext">{| class="wikitable"
|- {{#if: {{{variable_foo|}}} | | style="display: none;" }}
! Foo
| {{{variable_foo}}}
|-
! Bar
| {{{variable_bar}}}
|}</syntaxhighlight>

The code above is in {{tl|Conditional tables/example 2c}}. The table below demonstrates the effect when it is used:

{| class="wikitable"
|-
! Template call
! Result
|-
| {{tlx|Conditional tables/example 2c|variable_bar&#61;bar}}
| {{Conditional tables/example 2c|variable_bar=bar}}
|-
| {{tlx|Conditional tables/example 2c|variable_foo&#61;|variable_bar&#61;bar}}
| {{Conditional tables/example 2c|variable_foo=|variable_bar=bar}}
|-
| {{tlx|Conditional tables/example 2c|variable_foo&#61;foo}}
| {{Conditional tables/example 2c|variable_foo=foo}}
|-
| {{tlx|Conditional tables/example 2c|variable_foo&#61;foo|variable_bar&#61;bar}}
| {{Conditional tables/example 2c|variable_foo=foo|variable_bar=bar}}
|}

'''Pros and cons:''' with this method, there is no need for the wikitable pipe character to appear in the #if conditional, thus avoiding issues with [[#Vertical bar escaping|escaping the vertical bar ]]. However, sources and notes referred to in the hidden cells won't get suppressed with the other contents, so they will continue to be listed at the end of an article without any references to them occurring in the article's text.

===HTML tables===

One method of hiding rows in tables (or other structures within tables) uses HTML directly.<ref name="not_portable">Using HTML table code in templates can make them non-portable to other [[MediaWiki]] [[wiki]]s. This is because Wikipedia and other Wikimedia Foundation wikis process wikitext through [[HTML Tidy]]; most other wikis do not have the same setup, and the HTML table tags do not render. See [[Wikipedia:WikiProject Transwiki#Special templates]].</ref> In general, there are only a handful of HTML tags you need to be aware of

* <code><nowiki><tr></nowiki></code> - this tag creates a new row (similar to <code>|-</code> in MediaWiki table syntax)
* <code><nowiki><th></nowiki></code> - this tag creates a new header cell within a row (similar to <code>!</code> in MediaWiki table syntax)
* <code><nowiki><td></nowiki></code> - this tag creates a new cell within a row (similar to <code>|</code> in MediaWiki table syntax)
* <code><nowiki><caption></nowiki></code> - this tag creates a caption (similar to <code>|+</code> in MediaWiki table syntax)

A sample HTML table with a conditional row based on testing a template variable with {{kbd|#if}} follows:

<syntaxhighlight lang="wikitext">{| class="wikitable"
{{#if:{{{variable_foo|}}}
|<tr><th>Foo</th><td>{{{variable_foo}}}</td></tr>}}
|-
! Bar
| {{{variable_bar}}}
|}</syntaxhighlight>

The code above is in {{tl|Conditional tables/example 2a}}. As before, the table below demonstrates the effect when it's used:

{| class="wikitable"
|-
! Template call
! Result
|-
| {{tl|Conditional tables/example 2a}}
| {{Conditional tables/example 2a}}
|-
| {{tlp|Conditional tables/example 2a|variable_foo&#61;}}
| {{Conditional tables/example 2a|variable_foo=}}
|-
| {{tlp|Conditional tables/example 2a|variable_foo&#61;&#124;variable_bar&#61;bar}}
| {{Conditional tables/example 2a|variable_foo=|variable_bar=bar}}
|-
| {{tlp|Conditional tables/example 2a|variable_foo&#61;value}}
| {{Conditional tables/example 2a|variable_foo=value}}
|-
| {{tlp|Conditional tables/example 2a|variable_foo&#61;value&#124;variable_bar&#61;bar}}
| {{Conditional tables/example 2a|variable_foo=value|variable_bar=bar}}
|}

===Vertical bar escaping===

Because the parser function {{kbd|#if}} and  MediaWiki table syntax [[#Parser functions and table syntax|do not work together well]], the template code described at {{slink||Pitfalls}} with an illustration of non-working code at [[Template:Conditional tables/example 2|Example 2]] will not work correctly. The problems there can be rectified by properly escaping the vertical bar.

For most characters, often it's good enough to
replace a problematic characters with the corresponding [[HTML entities]], 
e.g. "{" by <kbd>&amp;#123;</kbd>, "|" by 
<kbd>&amp;#124;</kbd>, and "}" by <kbd>&amp;#125;</kbd>.
But for Wiki tables a real vertical bar character "|"  is required &mdash;
using <kbd>&amp;#124;</kbd> HTML entity does not work.

A simple trick allows to protect the "|" in template 
parameter values while still arriving as real "|" 
delimiter in the Wiki table, see the [[mw:Help:Magic_words#Escaped characters|magic word <nowiki>{{!}}</nowiki>]]. Note that
"!" (exclamation mark) has no problems with templates,
it's the other delimiter used in Wiki tables.
Here's the code for plan B:

<syntaxhighlight lang="wikitext">
{| class="wikitable"
{{#if:{{{foo|}}}|
{{!}}-
! Foo
{{!}} {{{foo}}}
}}
|-
! Bar
| {{{bar}}}
|}
</syntaxhighlight>

The code above is in {{tl|Conditional tables/example 2b}}. As before, 
the table below demonstrates the effect when it's used:

{| class="wikitable"
|-
! Template call
! Result
|-
| {{tlx|Conditional tables/example 2b|bar&#61;nobar}}
| {{Conditional tables/example 2b|bar=nobar}}
|-
| {{tlx|Conditional tables/example 2b|foo&#61;|bar&#61;vbar}}
| {{Conditional tables/example 2b|foo=|bar=vbar}}
|-
| {{tlx|Conditional tables/example 2b|foo&#61;value}}
| {{Conditional tables/example 2b|foo=value}}
|-
| {{tlx|Conditional tables/example 2b|foo&#61;value|bar&#61;vbar}}
| {{Conditional tables/example 2b|foo=value|bar=vbar}}
|}

==Refresher on parser functions==

{{further|mw:Help:Magic words#Parser functions|mw:Help:Extension:ParserFunctions}}

Conditional [[mw:Help:Extension:ParserFunctions|parser functions]] like {{kbd|#if}}  allow for the conditional display of table rows, columns or cells, but they have some limits.

The following example shows a basic use for <code>#if</code> that is available from the extension [[mw:Help:Extension:ParserFunctions|ParserFunctions]]:
<syntaxhighlight lang="wikitext">
 {{#if: {{{variable_foo|}}}
   |foo is set to '''{{{variable_foo}}}'''
   |foo is ''blank''
 }}
</syntaxhighlight>
Here, <code>{{{variable_foo}}}</code> is checked to see if it is defined with a non-blank value. The table below shows the output from a template call (we'll call the template {{tlx|Conditional tables/example 1}}) with different values for <code>{{{variable_foo}}}</code>:
<!-- NOTES:
&#61;  is an equal sign (=)
&#124; is a pipe symbol (|)
-->
{| class="wikitable"
|-
! Template call
! Result
|-
| {{tlx|Conditional tables/example 1}}
| {{Conditional tables/example 1}}
|-
| {{tlx|Conditional tables/example 1|variable_foo&#61;}}
| {{Conditional tables/example 1|variable_foo=}}
|-
| {{tlx|Conditional tables/example 1|variable_foo&#61;value}}
| {{Conditional tables/example 1|variable_foo=value}}
|}

Positional parameters <code>{{{1}}}</code> etc. work like named parameters:
<syntaxhighlight lang="wikitext">
 {{#if:{{{1|}}}
 |1st parameter is '''{{{1}}}'''
 |1st parameter is ''blank''}}
</syntaxhighlight>
{| class="wikitable"
|-
! Template call
! Result
|-
| {{tlx|Conditional tables/example 1b| &#124;bar}}
| {{Conditional tables/example 1b| |bar}}
|-
| {{tlx|Conditional tables/example 1b|foo&#124;bar}}
| {{Conditional tables/example 1b|foo|bar}}
|-
| {{tlx|Conditional tables/example 1b|[&#91;m:&#124;not empty&#93;]}}
| {{Conditional tables/example 1b|[[m:|not empty]]}}
|-
| {{tlx|Conditional tables/example 1b|bad&#61;idea}}
| {{Conditional tables/example 1b|bad=idea}}
|-
| {{tlx|Conditional tables/example 1b|1&#61;ok&#61;yes}}
| {{Conditional tables/example 1b|1=ok=yes}}
|}

Note how the ''pipe symbol'' (vertical bar) in the link works as is, it's not quite that easy within Wiki tables, see below.

===Pitfalls===

==== Parser functions and table syntax ====

Unfortunately <code>#if</code> and the MediaWiki table syntax do not work together well. For example, the following, {{tl|Conditional tables/example 2}} is '''invalid''' and will not work:

<syntaxhighlight lang="wikitext">{| class="wikitable"
{{#if:{{{variable_foo|}}}
|
|-
! Foo
| {{{variable_foo}}}
}}
|-
! Bar
| {{{variable_bar}}}
|}</syntaxhighlight>

The table below demonstrates the effect when {{tl|Conditional tables/example 2}} is used:

{| class="wikitable"
|-
! Template call
! Result
|-
| {{tl|Conditional tables/example 2}}
| {{Conditional tables/example 2}}
|-
| {{tlp|Conditional tables/example 2|variable_foo&#61;}}
| {{Conditional tables/example 2|variable_foo=}}
|-
| {{tlp|Conditional tables/example 2|variable_foo&#61;&#124;variable_bar&#61;bar}}
| {{Conditional tables/example 2|variable_foo=|variable_bar=bar}}
|-
| {{tlp|Conditional tables/example 2|variable_foo&#61;value}}
| {{Conditional tables/example 2|variable_foo=value}}
|-
| {{tlp|Conditional tables/example 2|variable_foo&#61;value&#124;variable_bar&#61;bar}}
| {{Conditional tables/example 2|variable_foo=value|variable_bar=bar}}
|}

The problem is with the usage of the pipe character (<code>|</code>). This character, in template calls, is used to separate parameters and so is invalid.

==Getting help==
If you find yourself unable to get a template to behave how you like, you can try asking on [[Wikipedia:Village pump (technical)|Village pump]], placing a request at [[Wikipedia:Requested templates|Requested templates]], or contacting an editor via [[WP:IRC|IRC]].

==See also==
For avoiding blank rows in the case of successive optional rows, see [[m:Help:Table#Conditional table row]].

For more information on <code>#if</code> (and other # functions), see:

* [[mw:Help:Extension:ParserFunctions]]

The following help topics deal with templates:

* [[m:Help:Template]]
* [[m:Help:Advanced templates]]

This help topic deals with table design (since most templates use tables, this may be useful):

* [[Help:Table]]

And finally:

* [[Help:Conditional expressions]]

==Notes and references ==
{{reflist}}
{{Wikipedia technical help|collapsed}}

[[Category:Wikipedia tables]]