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...
Public Member Functions | |
| __construct (IContextSource $context=null) | |
| doQuery () | |
| Do the query, using information from the object context. | |
| extractResultInfo ($isFirst, $limit, ResultWrapper $res) | |
| Extract some useful data from the result object for use by the navigation bar, put it into $this. | |
| formatRow ($row) | |
| Abstract formatting function. | |
| getBody () | |
| Get the formatted result list. | |
| getDatabase () | |
| Get the Database object in use. | |
| getDefaultQuery () | |
| Get an array of query parameters that should be put into self-links. | |
| getIndexField () | |
| This function should be overridden to return the name of the index fi- eld. | |
| getLimitLinks () | |
| getNumRows () | |
| Get the number of rows in the result set. | |
| getPagingLinks ($linkTexts, $disabledTexts=array()) | |
| Get paging links. | |
| getPagingQueries () | |
| Get a URL query array for the prev, next, first and last links. | |
| getQueryInfo () | |
| This function should be overridden to provide all parameters needed for the main paged query. | |
| getResult () | |
| getSqlComment () | |
| Get some text to go in brackets in the "function name" part of the SQL comment. | |
| isNavigationBarShown () | |
| Returns whether to show the "navigation bar". | |
| makeLink ($text, array $query=null, $type=null) | |
| Make a self-link. | |
| reallyDoQuery ($offset, $limit, $descending) | |
| Do a query with specified parameters, rather than using the object context. | |
| setIncludeOffset ($include) | |
| Set whether a row matching exactly the offset should be also included in the result or not. | |
| setLimit ($limit) | |
| Set the limit from an other source than the request. | |
| setOffset ($offset) | |
| Set the offset from an other source than the request. | |
Public Attributes | |
| $mDb | |
| $mDefaultDirection | |
| $mDefaultDirection gives the direction to use when sorting results: false for ascending, true for descending. | |
| $mDefaultLimit = 50 | |
| $mDefaultQuery | |
| $mFirstShown | |
| $mIsBackwards | |
| $mIsFirst | |
| True if the current result set is the first one. | |
| $mIsLast | |
| $mLimit | |
| $mLimitsShown = array( 20, 50, 100, 250, 500 ) | |
| $mNavigationBar | |
| $mOffset | |
| $mPastTheEndIndex | |
| $mPastTheEndRow | |
| $mQueryDone = false | |
| $mRequest | |
| ResultWrapper | $mResult |
| Result object for the query. | |
Protected Member Functions | |
| buildQueryInfo ($offset, $limit, $descending) | |
| Build variables to use by the database wrapper. | |
| doBatchLookups () | |
| Called from getBody(), before getStartBody() is called and after doQuery() was called. | |
| getDefaultDirections () | |
| Return the default sorting direction: false for ascending, true for descending. | |
| getEmptyBody () | |
| Hook into getBody(), for the bit between the start and the end when there are no rows. | |
| getEndBody () | |
| Hook into getBody() for the end of the list. | |
| getExtraSortFields () | |
| This function should be overridden to return the names of secondary columns to order by in addition to the column in getIndexField(). | |
| getStartBody () | |
| Hook into getBody(), allows text to be inserted at the start. | |
| preprocessResults ($result) | |
| Pre-process results; useful for performing batch existence checks, etc. | |
Protected Attributes | |
| $mExtraSortFields | |
| An array of secondary columns to order by. | |
| $mIncludeOffset = false | |
| Whether to include the offset in the query. | |
| $mIndexField | |
| The index to actually be used for ordering. | |
| $mLastShown | |
| $mOrderType | |
| For pages that support multiple types of ordering, which one to use. | |
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 HistoryPage.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.
Constructor & Destructor Documentation
| IndexPager::__construct | ( | IContextSource $ | context = null | ) |
Reimplemented in TablePager.
Definition at line 132 of file Pager.php.
References ContextSource\$context, $dir, array(), getDefaultDirections(), getExtraSortFields(), getIndexField(), ContextSource\getRequest(), ContextSource\getUser(), list, ContextSource\setContext(), and wfGetDB().
Member Function Documentation
| IndexPager::buildQueryInfo | ( | $ | offset, |
| $ | limit, | ||
| $ | descending | ||
| ) | [protected] |
Build variables to use by the database wrapper.
- Parameters:
-
string $offset index offset, inclusive $limit Integer: exact query limit $descending Boolean: query direction, false for ascending, true for descending
- Returns:
- array
Definition at line 369 of file Pager.php.
Referenced by ImageListPager\reallyDoQuery().
| 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
Reimplemented in ContribsPager, HistoryPager, ImageListPager, UsersPager, and ActiveUsersPager.
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.
Reimplemented in ImageHistoryPseudoPager, and LogPager.
| IndexPager::extractResultInfo | ( | $ | isFirst, |
| $ | limit, | ||
| ResultWrapper $ | res | ||
| ) |
Extract some useful data from the result object for use by the navigation bar, put it into $this.
- Parameters:
-
$isFirst bool: False if there are rows before those fetched (i.e. if a "previous" link would make sense) $limit Integer: exact query limit $res ResultWrapper
| 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:
-
$row Object: database row
- Returns:
- String
Reimplemented in ImageHistoryPseudoPager, TablePager, ContribsPager, NewPagesPager, MergeHistoryPager, ProtectedPagesPager, HistoryPager, AllmessagesTablePager, LogPager, ProtectedTitlesPager, UsersPager, DeletedContribsPager, ActiveUsersPager, NewFilesPager, and CategoryPager.
Get the formatted result list.
Calls getStartBody(), formatRow() and getEndBody(), concatenates the results and returns them.
- Returns:
- String
Implements Pager.
Reimplemented in ImageHistoryPseudoPager, and CategoryPager.
| IndexPager::getDefaultDirections | ( | ) | [protected] |
Return the default sorting direction: false for ascending, true for 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:
- Boolean
Reimplemented in CategoryPager.
Definition at line 724 of file Pager.php.
Referenced by __construct().
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
Reimplemented in ContribsPager, ImageListPager, UsersPager, CategoryPager, LogPager, and DeletedContribsPager.
| IndexPager::getEmptyBody | ( | ) | [protected] |
Hook into getBody(), for the bit between the start and the end when there are no rows.
- Returns:
- String
Reimplemented in TablePager.
| IndexPager::getEndBody | ( | ) | [protected] |
Hook into getBody() for the end of the list.
- Returns:
- String
Reimplemented in TablePager, ContribsPager, NewPagesPager, HistoryPager, NewFilesPager, and DeletedContribsPager.
| 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' => array( fields...) pairs in order for a request with &count=querykey to use array( 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:
- Array
Definition at line 701 of file Pager.php.
Referenced by __construct().
| 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|Array
Reimplemented in ImageHistoryPseudoPager, TablePager, ContribsPager, NewPagesPager, MergeHistoryPager, ProtectedPagesPager, BlockListPager, HistoryPager, LogPager, ProtectedTitlesPager, NewFilesPager, UsersPager, DeletedContribsPager, ActiveUsersPager, and CategoryPager.
Referenced by __construct().
Definition at line 630 of file Pager.php.
References $limit, array(), as, ContextSource\getLanguage(), and makeLink().
Referenced by DeletedContribsPager\getNavigationBar(), and ReverseChronologicalPager\getNavigationBar().
Get the number of rows in the result set.
- Returns:
- Integer
Definition at line 540 of file Pager.php.
Referenced by HistoryPager\getEndBody(), and LogPager\getStartBody().
| IndexPager::getPagingLinks | ( | $ | linkTexts, |
| $ | disabledTexts = array() |
||
| ) |
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:
-
$linkTexts Array $disabledTexts Array
- Returns:
- Array
Definition at line 609 of file Pager.php.
Referenced by DeletedContribsPager\getNavigationBar(), and ReverseChronologicalPager\getNavigationBar().
Get a URL query array for the prev, next, first and last links.
- Returns:
- Array
Reimplemented in ImageListPager.
| 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
Reimplemented in ImageHistoryPseudoPager, ContribsPager, NewPagesPager, MergeHistoryPager, AllmessagesTablePager, ProtectedPagesPager, BlockListPager, HistoryPager, ProtectedTitlesPager, LogPager, ImageListPager, UsersPager, ActiveUsersPager, CategoryPager, NewFilesPager, and DeletedContribsPager.
- Returns:
- ResultWrapper The result wrapper.
Get some text to go in brackets in the "function name" part of the SQL comment.
- Returns:
- String
Reimplemented in ContribsPager, and HistoryPager.
| 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
Reimplemented in TablePager, ContribsPager, NewPagesPager, MergeHistoryPager, HistoryPager, ProtectedPagesPager, AllmessagesTablePager, LogPager, ProtectedTitlesPager, NewFilesPager, and DeletedContribsPager.
Returns whether to show the "navigation bar".
- Returns:
- Boolean
Definition at line 591 of file Pager.php.
Referenced by ReverseChronologicalPager\getNavigationBar().
| IndexPager::makeLink | ( | $ | text, |
| array $ | query = null, |
||
| $ | type = null |
||
| ) |
Make a self-link.
- Parameters:
-
string $text text displayed on the link array $query associative array of parameter to be in the query string string $type value of the "rel" attribute
- Returns:
- String: HTML fragment
Definition at line 453 of file Pager.php.
Referenced by getLimitLinks().
| IndexPager::preprocessResults | ( | $ | result | ) | [protected] |
Pre-process results; useful for performing batch existence checks, etc.
- Parameters:
-
$result ResultWrapper
Reimplemented in BlockListPager.
| IndexPager::reallyDoQuery | ( | $ | offset, |
| $ | limit, | ||
| $ | descending | ||
| ) |
Do a query with specified parameters, rather than using the object context.
- Parameters:
-
string $offset index offset, inclusive $limit Integer: exact query limit $descending Boolean: query direction, false for ascending, true for descending
- Returns:
- ResultWrapper
Reimplemented in ContribsPager, ImageListPager, and AllmessagesTablePager.
| 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:
-
$include bool
Definition at line 276 of file Pager.php.
Referenced by CategoryPager\__construct().
| IndexPager::setLimit | ( | $ | limit | ) |
Set the limit from an other source than the request.
Verifies limit is between 1 and 5000
- Parameters:
-
$limit Int|String
Definition at line 258 of file Pager.php.
Referenced by NewFilesPager\__construct().
| IndexPager::setOffset | ( | $ | offset | ) |
Set the offset from an other source than the request.
- Parameters:
-
$offset Int|String
Definition at line 248 of file Pager.php.
Referenced by CategoryPager\__construct().
Member Data Documentation
| IndexPager::$mDb |
Reimplemented in ContribsPager, and DeletedContribsPager.
| IndexPager::$mDefaultDirection |
$mDefaultDirection gives the direction to use when sorting results: false for ascending, true for descending.
If $mIsBackwards is set, we start from the opposite end, but we still sort the page itself according to $mDefaultDirection. E.g., if $mDefaultDirection is false 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, $mDefaultDirection will be a single value even if the class supports multiple default directions for different order types.
Reimplemented in ReverseChronologicalPager, ContribsPager, and DeletedContribsPager.
IndexPager::$mExtraSortFields [protected] |
IndexPager::$mIncludeOffset = false [protected] |
IndexPager::$mIndexField [protected] |
| IndexPager::$mIsFirst |
| IndexPager::$mLimitsShown = array( 20, 50, 100, 250, 500 ) |
Reimplemented in AllmessagesTablePager.
| IndexPager::$mNavigationBar |
Reimplemented in DeletedContribsPager.
IndexPager::$mOrderType [protected] |
| ResultWrapper IndexPager::$mResult |
The documentation for this class was generated from the following file:
- includes/Pager.php
