Reusable code that treats forms as if they were table rows in a database
Reusable code that caches Foswiki topics, and provides fast
searches of the content.
Summary of Contents
This module supports fast structured queries over topics in an
arbitrarily-sized web. It uses a database to cache topic data to
deliver much more scaleable search performance. Different back-end
techologies can be used to implement the cache, to allow simple
tradeoffs between scaling and raw performance.
Historically this module was designed to be used with a
companion plugin, such as
Foswiki:Extensions.FormQueryPlugin or
Foswiki:Extensions.DBCachePlugin, which support queries and the display of
query results. When used this way, the
DBCacheContrib supports queries made using
a simple
query language.
The module can also be used in "standard schema mode" to support plugins
that accelerate core functions, such as the QueryAcceleratorPlugin.
Features
- Perform efficient structured queries on data in forms
Using the built-in query language
The query language supported by DBCacheContrib is very similar to the query language used with %SEARCH, which was derived from it. The contrib can be used in two modes; compatible schema mode (as used by
FormQueryPlugin and
DBCachePlugin) and standard schema mode (as described in
QuerySearch).
In standard schema mode the schema of the DB is as described in
QuerySearch.
In compatible schema mode, the underlying schema is somewhat different, to
support the extended requirements of the plugins that use it.
The Compatible Schema
You can think of the database as an map of all the topics in a web. Each
entry is itself a map (or hash, in perl terms) that maps a set of field
names to values.
Each topic in the web automatically gets a number of standard fields, generated
by reading the metadata from the topic (see
MetaData)
-
name - name of the topic
-
parent - name of parent topic
-
attachments - array of maps, each of which contains:
-
name - attachment name
-
attr - e.g hidden
-
comment - attachment comment
-
path - client path used to upload attachment
-
size - size in Kb
-
user - who uploaded the attachment
-
version - e.g. 1.3
-
info - map containing:
-
author - most recent author
-
date - date of last change
-
format - topic format version
-
version - topic version number
-
moved - map containing:
-
by - who moved it
-
date - when they moved it
-
from - where they moved it from
-
to - where they moved it to
-
preferences - array of maps, each of which contains:
-
name - preference name
-
type - either Set or Local
-
value - the value of the named preference
-
form - form type
- form name - e.g. if a "MyForm" is attached, this will be
MyForm. This is a reference to a map containing a key for each field in the form. Each key maps to the value in the form data for that key.
-
text - raw text of the topic)
Other fields may be added by subclasses. Refer to the documentation for the
plugin that is using the DBCache for more details.
Query operators
Fields are given by name, and values by strings or numbers. Strings should always be surrounded by 'single-quotes'. Strings which are regular expressions (RHS of =, != =~ operators) use 'perl' regular expression syntax (google for
perlre for help). Numbers can be signed integers or decimals. Single quotes in values may be escaped using backslash (\).
The following operators are available:
| Operator |
Result |
Meaning |
= |
Boolean |
LHS exactly matches the regular expression on the RHS. The expression must match the whole string. |
!= |
Boolean |
Inverse of = |
=~ |
Boolean |
LHS contains RHS i.e. the RHS is found somewhere in the field value. |
< |
Boolean |
Numeric < |
> |
Boolean |
Numeric > |
>= |
Boolean |
Numeric >= |
<= |
Boolean |
Numeric <= |
lc |
String |
Unary lower case |
uc |
String |
Unary UPPER CASE |
IS_DATE |
Boolean |
Compare two dates e.g. '1 Apr 2003' IS_DATE '1 Apr 2004' |
EARLIER_THAN |
Boolean |
Date is earlier than the given date |
EARLIER_THAN_OR_ON |
Boolean |
Date is earlier than, or on, the given date |
LATER_THAN |
Boolean |
LHS is later than the given date |
LATER_THAN_OR_ON |
Boolean |
LHS is later than the given date |
WITHIN_DAYS |
Boolean |
Date (which must be in the future) is within n working days of todays date |
! |
Boolean |
Unary NOT |
AND |
Boolean |
AND |
OR |
Boolean |
OR |
() |
any |
Bracketed subexpression |
Dates for the date operators (
IS_DATE,
EARLIER_THAN etc) must be dates in the format expected by
Time::ParseDate (like the
ActionTrackerPlugin).
WITHIN_DAYS works out the number of
working days assuming a 5 day week (i.e. excluding Saturday and Sunday). Apologies in advance if your weekend is offset ± a day! Integers will automatically be converted to dates, by assuming they represent a number of seconds since midnight GMT on 1st January 1970. You can also use the
d2n operator to convert a date string to such an integer.
The cache
To achieve best perfomance the plugin caches the data read from topics in a
database. The database is stored in the work area for the
DBCacheContrib (see
{WorkAreaDir} in
configure). If any topic changes in the web, this
cache is automatically updated.
Detailed Documentation
Clients use the DBCache by defining a subclass of the
Foswiki::Contrib::DBCacheContrib class. Implementors are stongly recommended to read the POD documentation in the code:
Installation Instructions
You do not need to install anything in the browser to use this extension. The following instructions are for the administrator who installs the extension on the server.
Open configure, and open the "Extensions" section. "Extensions Operation and Maintenance" Tab -> "Install, Update or Remove extensions" Tab. Click the "Search for Extensions" button.
Enter part of the extension name or description and press search. Select the desired extension(s) and click install. If an extension is already installed, it will
not show up in the
search results.
You can also install from the shell by running the extension installer as the web server user: (Be sure to run as the webserver user, not as root!)
cd /path/to/foswiki
perl tools/extension_installer <NameOfExtension> install
If you have any problems, or if the extension isn't available in
configure, then you can still install manually from the command-line. See
https://foswiki.org/Support/ManuallyInstallingExtensions for more help.
Copyright ©
This code is based on an original development of Motorola Inc. and is protected by the following copyrights:
Dependencies
| Name | Version | Description |
|---|
| Time::ParseDate | >=2003.0211 | Required. |
| Storable | >=2.07 | Required. |
| Sereal | >=3.00 | Optional |
| BerkeleyDB | >=0 | Optional, still experimental. |
Change History
Copyright © by the contributing authors. All material on this site is the property of the contributing authors.