Search Pattern Cookbook

The Search function is very powerful. Searches using a RegularExpression play an important part of tapping Foswiki's full potential. Unfortunately RegularExpressions can be incredibly obscure to the uninitiated.

Most people not familiar (enough) with Regular Expressions mostly cut and paste (and maybe tweak) from existing examples. This page intends to collect lots of examples together.

On this page:

Pattern 1: Extract values from a table

Problem definition

Suppose there is a topic with a table defining entries in a data form. I.e. they define select menu items in a form definition. They are then formatted like: 

| *Name*  | *Type* | *Tooltip message* |
| option1 | option |                   |
| option2 | option |                   |
| option3 | option |                   |

How to extract the 'name' values, i.e. 'option1', 'option2' and 'option3' and put them in a HTML form select input?

Solution 1

The following search pattern can be employed: 

%STARTSECTION{"solution1"}%
<form>
    <select>
        %SEARCH{
            "^\|[^\|]*\| *option *\|"
            topic="%TOPIC%"
            type="regex"
            multiple="on"
            nonoise="on"
            format="<option>$pattern(^\| *(.*?) *\|.*)</option>"
        }%
    </select>
</form>
%ENDSECTION{"solution1"}%

Click to execute

Solution 2

If your table has this format: 
| *Country*      |
|                |
| Afghanistan    |
| Aland Islands  |
| Albania        |
| Algeria        |
| American Samoa |
| Andorra        |

You need to skip the header row. Use this search: 
%STARTSECTION{"solution2"}%
<select>
    %SEARCH{
        "^\|[^\*\|]*\|"
        topic="CountryList"
        type="regex"
        multiple="on"
        nonoise="on"
        format="<option>$pattern(^\| *(.*?) *\|.*)</option>"
    }%
</select>
%ENDSECTION{"solution2"}%

Click to execute

Solution 3

If you want to grab the complete row for each occurrence of a string in a table, for instance the word "Marketing": 
| a | b | c | d | e |
| Marketing | b | c | d | e|
| a | b | c | d | e |
| a | marketing | c | d | e | 
| a | b | c | d | marketing |

use this query: 
%STARTSECTION{"solution3"}%
%SEARCH{
    "^\|.*?Marketing.*"
    type="regex"
    topic="%TOPIC%"
    multiple="on"
    nonoise="on"
    format="| $pattern(^\| *(.*?) *|.*)"
}%
%ENDSECTION{"solution3"}%

Click to execute

Pattern 2: List generated from form classification

Problem

Imagine a form-based topic classification, i.e. every page has a form with several fields. How to:
  1. create a search to display all topics where one form field is set to a certain value
  2. create a search to filter the list above based on the values of a second form field

Test case

In practice:
Image a form with two fields:

We will:
  1. List all topics where the TopicClassification field is set to 'Two'
  2. Enable the user to filter this list based on the values of TopicStatus

Solution 

%STARTSECTION{"solution4"}%
%SEARCH{
    "TopicClassification='%URLPARAM{"type" default="FrequentlyAskedQuestion"}%'"
    type="query"
    nonoise="on"
    sort="topic"
    format="   * [[$topic]] - <span class='foswikiGrayText'>$date, [[$wikiusername]]</span>"
}%
%ENDSECTION{"solution4"}%

Click to execute

The filtering select dialogue is created as in Pattern 1: 

%STARTSECTION{"solution5"}%
*Filter:* 
<form name="selectType" action="%SCRIPTURLPATH{"view"}%/%WEB%/" >
    <select name="type" size="1" onchange="document.location=this.value;"> 
        %SEARCH{
            "^\|[^\|]*\| *option *\|"
            topic="TopicClassification"
            type="regex" 
            nonoise="on"
            format="<option value='%BASETOPIC%?type=$pattern(^\| *(.*?) *\|.*)'>
                $pattern(^\| *(.*?) *\|.*)</option>"
        }% 
        <option value='%BASETOPIC%'>All pages</option>
    </select>
</form>
%ENDSECTION{"solution5"}%

This will create similar functionality as Foswiki:Extensions.TopicClassificationAddOn

Click to execute

Pattern 3: Extract the parent of a given topic

Problem

How to get to the parent of the current topic to display on the page?

Solution 1: Using QUERY

Use the QUERY macro: 

%STARTSECTION{"solution6"}%
Parent of [[%TOPIC%]] is [[%QUERY{ "parent.name" }%]]
%ENDSECTION{"solution6"}%

Click to execute

Pattern 4: Show all Children of a given topic

Problem

How to get to the list of all children of the current topic to display on the page?

Solution

The parent information is stored in the topic meta data. Do a SEARCH to find all topic parent meta data pointing to the current topic: 

%STARTSECTION{"solution7"}%
%SEARCH{
    "parent.name='%HOMETOPIC%'"
    type="query"
    nonoise="on"
    header="*Children:* "
    format="[[$topic]]"
    separator=", "
}%
%ENDSECTION{"solution7"}%

Click to execute

See also HierarchicalNavigation for an elaborate example.

Pattern 5: Search and display the home topics of public webs in a list

Problem

How to find and display public webs in a drop down list box.

Solution 

%STARTSECTION{"solution8"}%
<form>
    <select name="topic">
        <option value="%TOPIC%">Select...</option>
            %SEARCH{
                "%HOMETOPIC%"
                scope="topic"
                web="all"
                topic="%HOMETOPIC%"
                format="<option value='$web.$topic'>$web</option>"
                separator=" "
            }%
    </select>
    <input type="submit" class="foswikiSubmit" value="Go" />
</form>
%ENDSECTION{"solution8"}%

Public webs can be found with the %WEBLIST% macro.

Click to execute

Pattern 6: Create a select box with values from a bullet list

Problem

We have a topic with a bullet list with category names. In another topic we want to offer these values in a select box dropdown.

For example, CategoryList has:

Solution

The following search pattern can be employed: 

%STARTSECTION{"solution9"}%
<select name="type">
    <option>Select category...</option>
    %SEARCH{
        "   *\s*.*?"
        topic="CategoryList"
        type="regex"
        multiple="on"
        casesensitive="on"
        nonoise="on"
        format="<option>$pattern(.*   \*\s*([^
]*).*)</option>"
    }%
</select>
%ENDSECTION{"solution9"}%

Click to execute

To render the bullet list as a comma-separated list, use the separator parameter: 
%STARTSECTION{"solution10"}%
%SEARCH{
    "   *\s*.*?"
    topic="CategoryList"
    type="regex"
    multiple="on"
    casesensitive="on"
    nonoise="on"
    separator=","
    format="$pattern(.*   \*\s*([^
]*).*)"
}%
%ENDSECTION{"solution10"}%

Click to execute

Pattern 7: Search all topics that have been moved

Problem

How would I go about listing all moved topics ?

Solution

Search for the 'moved' meta data. 

%STARTSECTION{"solution11"}%
*Moved topics*: %SEARCH{
    "moved.from=~'\w+'"
    web="all"
    type="query"
    separator=", "
    format="[[$web.$topic]]"
    nonoise="on"
}%
%ENDSECTION{"solution11"}%

Click to execute

Pattern 8: Extract level-1 headings

How do I go about extracting the first occurance of a level-1 heading?

Solution

Use the $pattern() token. 

%STARTSECTION{"solution12"}%
%SEARCH{
    "^---[+][^+][^\r
]+[\r
]"
    type="regex"
    nonoise="on"
    header="Headings:"
    limit="5"
    format="   * [[$topic][$pattern([\r
\-+!]+([^\r
]*?)[\r
].*)]]"
    footer="Found $ntopics topics with level-1 headings"
}%
%ENDSECTION{"solution12"}%

Click to execute

Related Topics: UserDocumentationCategory, SearchHelp, Macros, FormattedSearch, RegularExpression 

%STARTSECTION{"click2exec"}%
%BUTTON{"Click to execute" onclick="jQuery('#%id%').trigger('refresh')"}%

<div class="jqLoader {mode:'manual', web:'%INCLUDINGWEB%', topic:'%INCLUDINGTOPIC%', section:'%id%'}" id="%id%"></div>
%JQREQUIRE{"loader"}%
%ENDSECTION{"click2exec"}%