This template tests whether the first unnamed parameter contains an error message and returns

  • the value of the first parameter prefixed by the third parameter value, and suffixed by the fourth parameter value, if there is an error;
  • the value of the second unnamed parameter, if given, or the first parameter value itself, if there is no error.

This is useful when the first parameter is an {{#invoke: }} of a Lua module that may return an error. Because it uses the {{#invoke: }} just once, it simplifies the coding of infoboxes, for example.

Usage

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{{#invoke:Infobox mapframe|auto}} called with improper coordinates
{{iferror then show |{{#invoke:Infobox mapframe|auto|onByDefault=yes|coordinates=10, 30}} |NO ERROR|PREFIX|SUFFIX}}PREFIXLua error in Module:Mapframe at line...SUFFIX


{{#invoke:Infobox mapframe|auto}} call that produces no errors
{{iferror then show |{{#invoke:Infobox mapframe|auto|onByDefault=yes}} |NO ERROR|PREFIX|SUFFIX}}NO ERROR

See also

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