Can a SEARCH take another SEARCH's output as input? How to search all webs and subwebs, while excluding subwebs of a particular web

Until Tasks.Item8893 is resolved, the excludeweb parameter of VarSEARCH only excludes the web specified; its subwebs are still candidates for any search result.

For example, consider the following search:

%SEARCH{
  "name='WebHome'"
  type="query"
  web="all"
  recurse="on"
  nonoise="on"
  format="   * [[$web.$topic][$topic]]"
}%

Test:

• About
• Community
• Community/Developers
• Development
• Download
• Extensions
• Extensions/Archived
• Extensions/Testing
• Home
• Main
• Sandbox
• WebHome
• Support/ClientSupport
• Support/Question922
• System
• Tasks
• Tasks/Testcases
• Trash/MiguelSandbox
• Trash/NC
• Trash/PoojaBedur
• Trash/StefanKrüger
• Trash/Subweb

Let's exclude Extensions web and all its subwebs. Sadly, this won't work, due to an open bug Tasks.Item8893:

%SEARCH{
  "name='WebHome'"
  type="query"
  web="all,-Extensions"
  recurse="on"
  nonoise="on"
  format="   * [[$web.$topic][$topic]]"
}%

So, let's try nesting a different SEARCH inside the outer SEARCH:

%SEARCH{
  "name='WebHome'"
  type="query"
  web="all,%SEARCH{
    "1"
    type="query"
    recurse="on"
    web="Extensions"
    topic="%WEBPREFSTOPIC%"
    nonoise="on"
    format="-$web"
    separator=", "
  }%"
  recurse="on"
  nonoise="on"
  format="   * [[$web.$topic][$topic]]"
}%

Test:

• About
• Community
• Community/Developers
• Development
• Download
• Home
• Main
• Sandbox
• WebHome
• Support/ClientSupport
• Support/Question922
• System
• Tasks
• Tasks/Testcases
• Trash/MiguelSandbox
• Trash/NC
• Trash/PoojaBedur
• Trash/StefanKrüger
• Trash/Subweb

How it works

Refer to the description of inside-out, left-to-right macro expansion documentation: the inner SEARCH expanded first, which was:

%SEARCH{
    "1"
    type="query"
    recurse="on"
    web="Extensions"
    topic="%WEBPREFSTOPIC%"
    nonoise="on"
    format="-$web"
    separator=", "
  }%

Result: -Extensions, -Extensions/Archived, -Extensions/Testing

And so the outer SEARCH actually saw this, prior to expansion:

   * [[About.WebHome][WebHome]]
   * [[Community.WebHome][WebHome]]
   * [[Community/Developers.WebHome][WebHome]]
   * [[Development.WebHome][WebHome]]
   * [[Download.WebHome][WebHome]]
   * [[Home.WebHome][WebHome]]
   * [[Main.WebHome][WebHome]]
   * [[Sandbox.WebHome][WebHome]]
   * [[Support.WebHome][WebHome]]
   * [[Support/ClientSupport.WebHome][WebHome]]
   * [[Support/Question922.WebHome][WebHome]]
   * [[System.WebHome][WebHome]]
   * [[Tasks.WebHome][WebHome]]
   * [[Tasks/Testcases.WebHome][WebHome]]
   * [[Trash/MiguelSandbox.WebHome][WebHome]]
   * [[Trash/NC.WebHome][WebHome]]
   * [[Trash/PoojaBedur.WebHome][WebHome]]
   * [[Trash/StefanKrüger.WebHome][WebHome]]
   * [[Trash/Subweb.WebHome][WebHome]]

See also

• Refer to VarSEARCH documentaiton for more about web/topic filters.
• Refer to the description of inside-out, left-to-right macro expansion in Foswiki