قالب:If empty/doc

Template:First nonempty and Template:Use first nonempty redirect here.

This is the {{if empty}} template.

This template is used inside other templates. It takes up to nine parameters (unnamed parameters 1-9) and returns the first found to be defined and non-empty. If none is found, nothing is returned. Typical usage is like this:

{{if empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}

("Return {{{logo|}}} if it has a value, else {{{image|}}} if it has a value, else {{{picture|}}} if it has a value, else return "default.svg".")

This returns the first of the parameters logo and image that is defined and non-empty, otherwise "default.svg".

 Rationale

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

The usual workaround for a single parameter is:

{{#if:{{{logo|}}} |{{{logo}}} |default.svg}}

("If {{{logo}}} has a value, return it, else return "default.svg".")

But this becomes complex when several parameters are to be checked:

{{#if:{{{logo|}}} |{{{logo}}} |{{#if:{{{image|}}} |{{{image}}} |{{#if:{{{picture|}}} |{{{picture}}} |default.svg}} }} }}

("If {{{logo}}} has a value, return it; else if {{{image}}} has a value, return that; else if {{{picture}}} has a value, return that; else return "default.svg".)

In these cases, {{if empty}} produces the simpler syntax (as above):

{{if empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}

 Piping

Parameters used with {{if empty}} must be piped – i.e. include the vertical bar (pipe) symbol (" | ") as a trailing character – so that empty or undefined parameters aren't treated as text and returned incorrectly. Hence, for example, {{{logo|}}}, {{{image|}}} and {{{picture|}}} rather than {{{logo}}}, {{{image}}} and {{{picture}}} in the above examples.

 Examples

Code	Result
{{if empty}}		Returns an empty string.
{{if empty|one}}	one	Returns the first parameter that is defined and not empty.
{{if empty|one|two}}	one
{{if empty|one|two|three|four}}	one
{{if empty||two}}	two	The first parameter is empty/undefined, so is passed over.
{{if empty||two|three|four}}	two
{{if empty||two||four}}	two
{{if empty|||||||||nine}}	nine
{{if empty||||||||||ten}}	ten	Empty string returned if maximum of nine parameters exceeded.
{{if empty|}}		The only parameter is empty or undefined, so returns an empty string.
{{if empty||||}}		Returns an empty string.
{{if empty|{{{1|}}}|{{{2|}}}|three}}	three
{{if empty|{{{1}}}|{{{2}}}|three}}	{{{1}}}	No pipe-characters following the names of the first two parameters ("1" and "2"), so the first of these returned as text ("{{{1}}}").
{{if empty|{{{logo|}}}|two}}	two
{{if empty|{{{logo}}}|two}}	{{{logo}}}	No pipe-character following the parameter name "logo", so the text "{{{logo}}}" returned.
{{if empty|2=x}}		Whether parameter 1 is undefined or empty does not matter.
{{if empty|p=q}}		The template identifies the parameters it receives as parameters 1 to 9, not using names such as "p", etc.

 See also

• قالب:Tlspc
• قالب:Tlspc
• قالب:Tlspc assists in handling image-width parameters within templates.
• Help:Parameter default