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2015-03-02T23:57:40Z

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2014-03-25T23:41:36Z

Created as needed.

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This is the {{tl|ifempty}} template.

This template is used inside other templates. It takes up to nine parameters (parameters 1-9), and returns the first one that is defined and non-empty, otherwise nothing. Typical usage is like this:

:<code><nowiki>{{ifempty| {{{logo|}}} | {{{image|}}} | default.svg }}</nowiki></code>
This returns the first of the parameters ''logo'' and ''image'' that is defined and non-empty, otherwise "default.svg".

=== Background ===

The MediaWiki parameter default function doesn't return the default value for empty parameters. That is, <code><nowiki>{{{logo|default.svg}}}</nowiki></code> does not return "default.svg" if the template was called like this: <code><nowiki>{{template|logo=}}</nowiki></code>.

The usual workaround is to do like this:
:<code><nowiki>{{#if:{{{logo|}}}| {{{logo}}} | default.svg }}</nowiki></code>

But this becomes complex when you want to check several parameters:

:<code><nowiki>{{#if:{{{logo|}}}| {{{logo}}} | {{#if:{{{image|}}} | {{{image}}} | default.svg }}}}</nowiki></code>

Then it is easier to use this template instead:

:<code><nowiki>{{ifempty| {{{logo|}}} | {{{image|}}} | default.svg }}</nowiki></code>

'''Note!''' The parameters to {{tlf|ifempty}} must use the pipe "|", like this: <code><nowiki>{{{logo|}}}</nowiki></code>. Or else {{tlf|ifempty}} will be fed and return the string "<code><nowiki>{{{logo}}}</nowiki></code>" if ''logo'' was not defined.

=== Examples ===

<table class="wikitable">
<tr><th>Code<th>Result<th>Comment
<tr><td>{{tlc|ifempty}} <td>{{ifempty}} <td>Returns an empty string.
<tr><td>{{tlc|ifempty|one}} <td>{{ifempty|one}} <td>Returns the first parameter that is defined and not empty.
<tr><td>{{tlc|ifempty|one|two}} <td>{{ifempty|one|two}} <td>
<tr><td>{{tlc|ifempty|one|two|three|four}} <td>{{ifempty|one|two|three|four}} <td>
<tr><td>{{tlc|ifempty||two}} <td>{{ifempty||two}} <td>The first parameter was empty or undefined, so uses the next parameter.
<tr><td>{{tlc|ifempty||two|three|four}} <td>{{ifempty||two|three|four}} <td>
<tr><td>{{tlc|ifempty||two||four}} <td>{{ifempty||two||four}} <td>
<tr><td><code><nowiki>{{ifempty|||||||||nine}}</nowiki></code> <td>{{ifempty|||||||||nine}} <td>
<tr><td><code><nowiki>{{ifempty||||||||||ten}}</nowiki></code> <td>{{ifempty||||||||||ten}} <td>Only handles up to nine parameters, so returns an empty string.
<tr><td>{{tlc|ifempty|}} <td>{{ifempty|}} <td>The only parameter is empty or undefined, so returns an empty string.
<tr><td>{{tlc|ifempty||||}} <td>{{ifempty||||}} <td>Returns an empty string.

<tr><td><code><nowiki>{{ifempty|{{{1|}}}|{{{2|}}}|three}}</nowiki></code> <td>{{ifempty|{{{1|}}}|{{{2|}}}|three}} <td>
<tr><td><code><nowiki>{{ifempty|{{{1}}}|{{{2}}}|three}}</nowiki></code> <td>{{ifempty|{{{1}}}|{{{2}}}|three}} <td>Returns the text "{{{1}}}", because it is a non-empty string. Note the lack of "|" in the first two parameters.

<tr><td><code><nowiki>{{ifempty|{{{logo|}}}|two}}</nowiki></code> <td>{{ifempty|{{{logo|}}}|two}} <td>
<tr><td><code><nowiki>{{ifempty|{{{logo}}}|two}}</nowiki></code> <td>{{ifempty|{{{logo}}}|two}} <td>Returns the text "{{{logo}}}", because it is a non-empty string. Note the lack of "|" in the first parameter.
<tr><td><code><nowiki>{{ifempty|2=x}}</nowiki></code> <td>{{ifempty|2=x}} <td>Whether parameter 1 is undefined or empty does not matter.
<tr><td><code><nowiki>{{ifempty|p=q}}</nowiki></code> <td>{{ifempty|p=q}} <td>The template checks its parameters 1-9, not other ones.
</table>

=== See also ===

* {{tl|px}} – Helps handling image width parameters in templates.

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[[Category:If-then-else templates|{{PAGENAME}}]]
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