MediaWiki  master
IndexPager Class Reference

IndexPager is an efficient pager which uses a (roughly unique) index in the data set to implement paging, rather than a "LIMIT offset,limit" clause. More...

Inheritance diagram for IndexPager:
Collaboration diagram for IndexPager:

Public Member Functions

 __construct (IContextSource $context=null)
 
 doQuery ()
 Do the query, using information from the object context. More...
 
 extractResultInfo ( $isFirst, $limit, IResultWrapper $res)
 Extract some useful data from the result object for use by the navigation bar, put it into $this. More...
 
 formatRow ( $row)
 Abstract formatting function. More...
 
 getBody ()
 Get the formatted result list. More...
 
 getDatabase ()
 Get the Database object in use. More...
 
 getDefaultQuery ()
 Get an array of query parameters that should be put into self-links. More...
 
 getIndexField ()
 This function should be overridden to return the name of the index fi- eld. More...
 
 getLimit ()
 Get the current limit. More...
 
 getLimitLinks ()
 
 getNumRows ()
 Get the number of rows in the result set. More...
 
 getPagingLinks ( $linkTexts, $disabledTexts=[])
 Get paging links. More...
 
 getPagingQueries ()
 Get a URL query array for the prev, next, first and last links. More...
 
 getQueryInfo ()
 This function should be overridden to provide all parameters needed for the main paged query. More...
 
 getResult ()
 
 getSqlComment ()
 Get some text to go in brackets in the "function name" part of the SQL comment. More...
 
 isNavigationBarShown ()
 Returns whether to show the "navigation bar". More...
 
 makeLink ( $text, array $query=null, $type=null)
 Make a self-link. More...
 
 reallyDoQuery ( $offset, $limit, $order)
 Do a query with specified parameters, rather than using the object context. More...
 
 setIncludeOffset ( $include)
 Set whether a row matching exactly the offset should be also included in the result or not. More...
 
 setLimit ( $limit)
 Set the limit from an other source than the request. More...
 
 setOffset ( $offset)
 Set the offset from an other source than the request. More...
 
- Public Member Functions inherited from ContextSource
 canUseWikiPage ()
 Check whether a WikiPage object can be get with getWikiPage(). More...
 
 exportSession ()
 Export the resolved user IP, HTTP headers, user ID, and session ID. More...
 
 getConfig ()
 
 getContext ()
 Get the base IContextSource object. More...
 
 getLanguage ()
 
 getOutput ()
 
 getRequest ()
 
 getSkin ()
 
 getStats ()
 
 getTiming ()
 
 getTitle ()
 
 getUser ()
 
 getWikiPage ()
 Get the WikiPage object. More...
 
 msg ( $key)
 Get a Message object with context set Parameters are the same as wfMessage() More...
 
 setContext (IContextSource $context)
 
- Public Member Functions inherited from Pager
 getNavigationBar ()
 

Public Attributes

IDatabase $mDb
 
bool $mDefaultDirection
 $mDefaultDirection gives the direction to use when sorting results: DIR_ASCENDING or DIR_DESCENDING. More...
 
int $mDefaultLimit = 50
 The default entry limit choosen for clients. More...
 
bool $mIsBackwards
 
bool $mIsFirst
 True if the current result set is the first one. More...
 
bool $mIsLast
 
int $mLimit
 The maximum number of entries to show. More...
 
int [] $mLimitsShown = [ 20, 50, 100, 250, 500 ]
 List of default entry limit options to be presented to clients. More...
 
mixed $mOffset
 The starting point to enumerate entries. More...
 
stdClass bool null $mPastTheEndRow
 Extra row fetched at the end to see if the end was reached. More...
 
bool $mQueryDone = false
 Whether the listing query completed. More...
 
WebRequest $mRequest
 
IResultWrapper $mResult
 Result object for the query. More...
 
const DIR_ASCENDING = false
 Backwards-compatible constant for $mDefaultDirection field (do not change) More...
 
const DIR_DESCENDING = true
 Backwards-compatible constant for $mDefaultDirection field (do not change) More...
 
const QUERY_ASCENDING = true
 Backwards-compatible constant for reallyDoQuery() (do not change) More...
 
const QUERY_DESCENDING = false
 Backwards-compatible constant for reallyDoQuery() (do not change) More...
 

Protected Member Functions

 buildPrevNextNavigation (LinkTarget $title, $offset, $limit, array $query=[], $atend=false)
 Generate (prev x| next x) (20|50|100...) type links for paging. More...
 
 buildQueryInfo ( $offset, $limit, $order)
 Build variables to use by the database wrapper. More...
 
 doBatchLookups ()
 Called from getBody(), before getStartBody() is called and after doQuery() was called. More...
 
 getDefaultDirections ()
 Return the default sorting direction: DIR_ASCENDING or DIR_DESCENDING. More...
 
 getEmptyBody ()
 Hook into getBody(), for the bit between the start and the end when there are no rows. More...
 
 getEndBody ()
 Hook into getBody() for the end of the list. More...
 
 getExtraSortFields ()
 This function should be overridden to return the names of secondary columns to order by in addition to the column in getIndexField(). More...
 
 getStartBody ()
 Hook into getBody(), allows text to be inserted at the start. More...
 
 preprocessResults ( $result)
 Pre-process results; useful for performing batch existence checks, etc. More...
 

Static Protected Member Functions

static oppositeOrder ( $order)
 

Protected Attributes

array $mDefaultQuery
 
string [] $mExtraSortFields
 An array of secondary columns to order by. More...
 
mixed $mFirstShown
 
bool $mIncludeOffset = false
 Whether to include the offset in the query. More...
 
string $mIndexField
 The index to actually be used for ordering. More...
 
mixed $mLastShown
 
string $mNavigationBar
 
string null $mOrderType
 For pages that support multiple types of ordering, which one to use. More...
 
mixed $mPastTheEndIndex
 

Detailed Description

IndexPager is an efficient pager which uses a (roughly unique) index in the data set to implement paging, rather than a "LIMIT offset,limit" clause.

In MySQL, such a limit/offset clause requires counting through the specified number of offset rows to find the desired data, which can be expensive for large offsets.

ReverseChronologicalPager is a child class of the abstract IndexPager, and contains some formatting and display code which is specific to the use of timestamps as indexes. Here is a synopsis of its operation:

  • The query is specified by the offset, limit and direction (dir) parameters, in addition to any subclass-specific parameters.
  • The offset is the non-inclusive start of the DB query. A row with an index value equal to the offset will never be shown.
  • The query may either be done backwards, where the rows are returned by the database in the opposite order to which they are displayed to the user, or forwards. This is specified by the "dir" parameter, dir=prev means backwards, anything else means forwards. The offset value specifies the start of the database result set, which may be either the start or end of the displayed data set. This allows "previous" links to be implemented without knowledge of the index value at the start of the previous page.
  • An additional row beyond the user-specified limit is always requested. This allows us to tell whether we should display a "next" link in the case of forwards mode, or a "previous" link in the case of backwards mode. Determining whether to display the other link (the one for the page before the start of the database result set) can be done heuristically by examining the offset.
  • An empty offset indicates that the offset condition should be omitted from the query. This naturally produces either the first page or the last page depending on the dir parameter.

Subclassing the pager to implement concrete functionality should be fairly simple, please see the examples in HistoryAction.php and SpecialBlockList.php. You just need to override formatRow(), getQueryInfo() and getIndexField(). Don't forget to call the parent constructor if you override it.

Definition at line 71 of file IndexPager.php.

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ buildPrevNextNavigation()

IndexPager::buildPrevNextNavigation ( LinkTarget  $title,
  $offset,
  $limit,
array  $query = [],
  $atend = false 
)
protected

Generate (prev x| next x) (20|50|100...) type links for paging.

Parameters
LinkTarget$title
int$offset
int$limit
array$queryOptional URL query parameter string
bool$atendOptional param for specified if this is the last page
Returns
string

Definition at line 800 of file IndexPager.php.

References $query.

◆ buildQueryInfo()

IndexPager::buildQueryInfo (   $offset,
  $limit,
  $order 
)
protected

Build variables to use by the database wrapper.

Note
For b/c, query direction is true for ascending and false for descending
Parameters
string$offsetIndex offset, inclusive
int$limitExact query limit
bool$orderIndexPager::QUERY_ASCENDING or IndexPager::QUERY_DESCENDING
Returns
array

Definition at line 426 of file IndexPager.php.

References $fname, $options, $tables, as, getQueryInfo(), and getSqlComment().

Referenced by ImageListPager\reallyDoQuery(), and reallyDoQuery().

◆ doBatchLookups()

IndexPager::doBatchLookups ( )
protected

Called from getBody(), before getStartBody() is called and after doQuery() was called.

This will be called only if there are rows in the result set.

Returns
void

Definition at line 544 of file IndexPager.php.

Referenced by getBody().

◆ doQuery()

IndexPager::doQuery ( )

Do the query, using information from the object context.

This function has been kept minimal to make it overridable if necessary, to allow for result sets formed from multiple DB queries.

Definition at line 228 of file IndexPager.php.

References $fname, $mIncludeOffset, $section, class, extractResultInfo(), Profiler\instance(), preprocessResults(), and reallyDoQuery().

Referenced by getBody(), getNumRows(), getPagingQueries(), and isNavigationBarShown().

◆ extractResultInfo()

IndexPager::extractResultInfo (   $isFirst,
  $limit,
IResultWrapper  $res 
)

Extract some useful data from the result object for use by the navigation bar, put it into $this.

Parameters
bool$isFirstFalse if there are rows before those fetched (i.e. if a "previous" link would make sense)
int$limitExact query limit
IResultWrapper$res

Definition at line 341 of file IndexPager.php.

References Wikimedia\Rdbms\IResultWrapper\fetchObject(), Wikimedia\Rdbms\IResultWrapper\fetchRow(), null, Wikimedia\Rdbms\IResultWrapper\numRows(), and Wikimedia\Rdbms\IResultWrapper\seek().

Referenced by doQuery().

◆ formatRow()

IndexPager::formatRow (   $row)
abstract

Abstract formatting function.

This should return an HTML string representing the result row $row. Rows will be concatenated and returned by getBody()

Parameters
array | stdClass$rowDatabase row
Returns
string

Referenced by getBody(), and getLimitLinks().

◆ getBody()

IndexPager::getBody ( )

Get the formatted result list.

Calls getStartBody(), formatRow() and getEndBody(), concatenates the results and returns them.

Returns
string

Implements Pager.

Definition at line 467 of file IndexPager.php.

References $mLimit, $s, doBatchLookups(), doQuery(), formatRow(), getEmptyBody(), getEndBody(), and getStartBody().

◆ getDatabase()

IndexPager::getDatabase ( )

Get the Database object in use.

Returns
IDatabase

Definition at line 219 of file IndexPager.php.

References $mDb.

Referenced by ActiveUsersPager\doBatchLookups(), ActiveUsersPager\getQueryInfo(), BlockListPager\getQueryInfo(), and BlockListPager\getTotalAutoblocks().

◆ getDefaultDirections()

IndexPager::getDefaultDirections ( )
protected

Return the default sorting direction: DIR_ASCENDING or DIR_DESCENDING.

You can also have an associative array of ordertype => dir, if multiple order types are supported. In this case getIndexField() must return an array, and the keys of that must exactly match the keys of this.

For backward compatibility, this method's return value will be ignored if $this->mDefaultDirection is already set when the constructor is called, for instance if it's statically initialized. In that case the value of that variable (which must be a boolean) will be used.

Note that despite its name, this does not return the value of the $this->mDefaultDirection member variable. That's the default for this particular instantiation, which is a single value. This is the set of all defaults for the class.

Returns
bool

Definition at line 786 of file IndexPager.php.

Referenced by __construct().

◆ getDefaultQuery()

IndexPager::getDefaultQuery ( )

Get an array of query parameters that should be put into self-links.

By default, all parameters passed in the URL are used, except for a short blacklist.

Returns
array Associative array

Definition at line 583 of file IndexPager.php.

References $mDefaultQuery, and ContextSource\getRequest().

Referenced by makeLink().

◆ getEmptyBody()

IndexPager::getEmptyBody ( )
protected

Hook into getBody(), for the bit between the start and the end when there are no rows.

Returns
string

Definition at line 572 of file IndexPager.php.

Referenced by getBody().

◆ getEndBody()

IndexPager::getEndBody ( )
protected

Hook into getBody() for the end of the list.

Returns
string

Definition at line 562 of file IndexPager.php.

Referenced by getBody().

◆ getExtraSortFields()

IndexPager::getExtraSortFields ( )
protected

This function should be overridden to return the names of secondary columns to order by in addition to the column in getIndexField().

These fields will not be used in the pager offset or in any links for users.

If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then this must return a corresponding array of 'querykey' => [ fields... ] pairs in order for a request with &count=querykey to use [ fields... ] to sort.

This is useful for pagers that GROUP BY a unique column (say page_id) and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on page_len,page_id avoids temp tables (given a page_len index). This would also work if page_id was non-unique but we had a page_len,page_id index.

Returns
string[]|array[]

Definition at line 763 of file IndexPager.php.

Referenced by __construct().

◆ getIndexField()

IndexPager::getIndexField ( )
abstract

This function should be overridden to return the name of the index fi- eld.

If the pager supports multiple orders, it may return an array of 'querykey' => 'indexfield' pairs, so that a request with &count=querykey will use indexfield to sort. In this case, the first returned key is the default.

Needless to say, it's really not a good idea to use a non-unique index for this! That won't page right.

Returns
string|string[]

Referenced by __construct(), getLimitLinks(), and AlphabeticPager\getNavigationBar().

◆ getLimit()

IndexPager::getLimit ( )

Get the current limit.

Returns
int

Definition at line 317 of file IndexPager.php.

References $mLimit.

◆ getLimitLinks()

◆ getNumRows()

IndexPager::getNumRows ( )

◆ getPagingLinks()

IndexPager::getPagingLinks (   $linkTexts,
  $disabledTexts = [] 
)

Get paging links.

If a link is disabled, the item from $disabledTexts will be used. If there is no such item, the unlinked text from $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays of HTML.

Parameters
array$linkTexts
array$disabledTexts
Returns
array

Definition at line 671 of file IndexPager.php.

References $queries, $query, $type, as, getPagingQueries(), and makeLink().

Referenced by AlphabeticPager\getNavigationBar(), ReverseChronologicalPager\getNavigationBar(), and DeletedContribsPager\getNavigationBar().

◆ getPagingQueries()

IndexPager::getPagingQueries ( )

Get a URL query array for the prev, next, first and last links.

Returns
array

Definition at line 614 of file IndexPager.php.

References $last, $mFirstShown, $mLastShown, $mLimit, doQuery(), and null.

Referenced by TablePager\getNavigationBar(), and getPagingLinks().

◆ getQueryInfo()

IndexPager::getQueryInfo ( )
abstract

This function should be overridden to provide all parameters needed for the main paged query.

It returns an associative array with the following elements: tables => Table(s) for passing to Database::select() fields => Field(s) for passing to Database::select(), may be * conds => WHERE conditions options => option array join_conds => JOIN conditions

Returns
array

Referenced by buildQueryInfo(), and getLimitLinks().

◆ getResult()

IndexPager::getResult ( )
Returns
IResultWrapper The result wrapper.

Definition at line 281 of file IndexPager.php.

References $mResult.

◆ getSqlComment()

IndexPager::getSqlComment ( )

Get some text to go in brackets in the "function name" part of the SQL comment.

Returns
string

Definition at line 395 of file IndexPager.php.

References class.

Referenced by ActiveUsersPager\buildQueryInfo(), buildQueryInfo(), and ActiveUsersPager\getQueryInfo().

◆ getStartBody()

IndexPager::getStartBody ( )
protected

Hook into getBody(), allows text to be inserted at the start.

This will be called even if there are no rows in the result set.

Returns
string

Definition at line 553 of file IndexPager.php.

Referenced by getBody().

◆ isNavigationBarShown()

IndexPager::isNavigationBarShown ( )

Returns whether to show the "navigation bar".

Returns
bool

Definition at line 653 of file IndexPager.php.

References $mIsLast, and doQuery().

Referenced by AlphabeticPager\getNavigationBar(), ReverseChronologicalPager\getNavigationBar(), and TablePager\getNavigationBar().

◆ makeLink()

IndexPager::makeLink (   $text,
array  $query = null,
  $type = null 
)

Make a self-link.

Parameters
string$textText displayed on the link
array | null$queryAssociative array of parameter to be in the query string
string | null$typeLink type used to create additional attributes, like "rel", "class" or "title". Valid values (non-exhaustive list): 'first', 'last', 'prev', 'next', 'asc', 'desc'.
Returns
string HTML fragment

Definition at line 511 of file IndexPager.php.

References $query, $type, getDefaultQuery(), ContextSource\getTitle(), Linker\linkKnown(), ContextSource\msg(), and null.

Referenced by getLimitLinks(), AlphabeticPager\getNavigationBar(), getPagingLinks(), and TablePager\getStartBody().

◆ oppositeOrder()

static IndexPager::oppositeOrder (   $order)
staticfinalprotected
Parameters
bool$orderOne of the IndexPager::QUERY_* class constants
Returns
bool The opposite query order as an IndexPager::QUERY_ constant

Definition at line 272 of file IndexPager.php.

◆ preprocessResults()

IndexPager::preprocessResults (   $result)
protected

Pre-process results; useful for performing batch existence checks, etc.

Parameters
IResultWrapper$result

Definition at line 458 of file IndexPager.php.

Referenced by doQuery().

◆ reallyDoQuery()

IndexPager::reallyDoQuery (   $offset,
  $limit,
  $order 
)

Do a query with specified parameters, rather than using the object context.

Note
For b/c, query direction is true for ascending and false for descending
Parameters
string$offsetIndex offset, inclusive
int$limitExact query limit
bool$orderIndexPager::QUERY_ASCENDING or IndexPager::QUERY_DESCENDING
Returns
IResultWrapper

Definition at line 409 of file IndexPager.php.

References $fname, $options, $tables, buildQueryInfo(), and list.

Referenced by doQuery().

◆ setIncludeOffset()

IndexPager::setIncludeOffset (   $include)

Set whether a row matching exactly the offset should be also included in the result or not.

By default this is not the case, but when the offset is user-supplied this might be wanted.

Parameters
bool$include

Definition at line 328 of file IndexPager.php.

Referenced by CategoryPager\__construct().

◆ setLimit()

IndexPager::setLimit (   $limit)

Set the limit from an other source than the request.

Verifies limit is between 1 and 5000

Parameters
int | string$limit

Definition at line 301 of file IndexPager.php.

Referenced by NewFilesPager\__construct().

◆ setOffset()

IndexPager::setOffset (   $offset)

Set the offset from an other source than the request.

Parameters
int | string$offset

Definition at line 290 of file IndexPager.php.

Referenced by CategoryPager\__construct().

Member Data Documentation

◆ $mDb

IDatabase IndexPager::$mDb

Definition at line 95 of file IndexPager.php.

Referenced by getDatabase(), and LogPager\limitTitle().

◆ $mDefaultDirection

bool IndexPager::$mDefaultDirection

$mDefaultDirection gives the direction to use when sorting results: DIR_ASCENDING or DIR_DESCENDING.

If $mIsBackwards is set, we start from the opposite end, but we still sort the page itself according to $mDefaultDirection. For example, if $mDefaultDirection is DIR_ASCENDING but we're going backwards, we'll display the last page of results, but the last result will be at the bottom, not the top.

Like $mIndexField, $mDefaultDirection will be a single value even if the class supports multiple default directions for different order types.

Definition at line 127 of file IndexPager.php.

Referenced by UsersPager\getPageHeader().

◆ $mDefaultLimit

int IndexPager::$mDefaultLimit = 50

The default entry limit choosen for clients.

Definition at line 87 of file IndexPager.php.

◆ $mDefaultQuery

array IndexPager::$mDefaultQuery
protected

◆ $mExtraSortFields

string [] IndexPager::$mExtraSortFields
protected

An array of secondary columns to order by.

These fields are not part of the offset. This is a column list for one ordering, even if multiple orderings are supported.

Definition at line 110 of file IndexPager.php.

◆ $mFirstShown

mixed IndexPager::$mFirstShown
protected

Definition at line 139 of file IndexPager.php.

Referenced by getPagingQueries().

◆ $mIncludeOffset

bool IndexPager::$mIncludeOffset = false
protected

Whether to include the offset in the query.

Definition at line 151 of file IndexPager.php.

Referenced by doQuery().

◆ $mIndexField

string IndexPager::$mIndexField
protected

The index to actually be used for ordering.

This is a single column, for one ordering, even if multiple orderings are supported.

Definition at line 104 of file IndexPager.php.

Referenced by ImageListPager\reallyDoQuery().

◆ $mIsBackwards

bool IndexPager::$mIsBackwards

Definition at line 129 of file IndexPager.php.

◆ $mIsFirst

bool IndexPager::$mIsFirst

True if the current result set is the first one.

Definition at line 132 of file IndexPager.php.

◆ $mIsLast

bool IndexPager::$mIsLast

Definition at line 134 of file IndexPager.php.

Referenced by isNavigationBarShown().

◆ $mLastShown

mixed IndexPager::$mLastShown
protected

Definition at line 137 of file IndexPager.php.

Referenced by getPagingQueries().

◆ $mLimit

int IndexPager::$mLimit

◆ $mLimitsShown

int [] IndexPager::$mLimitsShown = [ 20, 50, 100, 250, 500 ]

List of default entry limit options to be presented to clients.

Definition at line 85 of file IndexPager.php.

◆ $mNavigationBar

string IndexPager::$mNavigationBar
protected

◆ $mOffset

mixed IndexPager::$mOffset

The starting point to enumerate entries.

Definition at line 89 of file IndexPager.php.

Referenced by ImageHistoryPseudoPager\doQuery(), ReverseChronologicalPager\getDateCond(), RangeChronologicalPager\getDateCond(), and getLimitLinks().

◆ $mOrderType

string null IndexPager::$mOrderType
protected

For pages that support multiple types of ordering, which one to use.

Definition at line 114 of file IndexPager.php.

Referenced by __construct().

◆ $mPastTheEndIndex

mixed IndexPager::$mPastTheEndIndex
protected

Definition at line 141 of file IndexPager.php.

Referenced by getLimitLinks().

◆ $mPastTheEndRow

stdClass bool null IndexPager::$mPastTheEndRow

Extra row fetched at the end to see if the end was reached.

Definition at line 97 of file IndexPager.php.

Referenced by HistoryPager\getEndBody().

◆ $mQueryDone

bool IndexPager::$mQueryDone = false

Whether the listing query completed.

Definition at line 93 of file IndexPager.php.

◆ $mRequest

WebRequest IndexPager::$mRequest

Definition at line 83 of file IndexPager.php.

◆ $mResult

IResultWrapper IndexPager::$mResult

Result object for the query.

Warning: seek before use.

Definition at line 158 of file IndexPager.php.

Referenced by getResult().

◆ DIR_ASCENDING

const IndexPager::DIR_ASCENDING = false

Backwards-compatible constant for $mDefaultDirection field (do not change)

Definition at line 73 of file IndexPager.php.

Referenced by TablePager\__construct(), UsersPager\__construct(), and ImageListPager\__construct().

◆ DIR_DESCENDING

const IndexPager::DIR_DESCENDING = true

Backwards-compatible constant for $mDefaultDirection field (do not change)

Definition at line 75 of file IndexPager.php.

Referenced by TablePager\__construct(), UsersPager\__construct(), BlockListPager\__construct(), ImageListPager\__construct(), AllMessagesTablePager\__construct(), and TablePager\getStartBody().

◆ QUERY_ASCENDING

const IndexPager::QUERY_ASCENDING = true

Backwards-compatible constant for reallyDoQuery() (do not change)

Definition at line 78 of file IndexPager.php.

◆ QUERY_DESCENDING

const IndexPager::QUERY_DESCENDING = false

Backwards-compatible constant for reallyDoQuery() (do not change)

Definition at line 80 of file IndexPager.php.


The documentation for this class was generated from the following file: