DBIx::SearchBuilder(3pm) User Contributed Perl Documentation DBIx::SearchBuilder(3pm)
NAME
DBIx::SearchBuilder - Encapsulate SQL queries and rows in simple perl objects
SYNOPSIS
use DBIx::SearchBuilder;
package My::Things;
use base qw/DBIx::SearchBuilder/;
sub _Init {
my $self = shift;
$self->Table('Things');
return $self->SUPER::_Init(@_);
}
sub NewItem {
my $self = shift;
# MyThing is a subclass of DBIx::SearchBuilder::Record
return(MyThing->new);
}
package main;
use DBIx::SearchBuilder::Handle;
my $handle = DBIx::SearchBuilder::Handle->new();
$handle->Connect( Driver => 'SQLite', Database => "my_test_db" );
my $sb = My::Things->new( Handle => $handle );
$sb->Limit( FIELD => "column_1", VALUE => "matchstring" );
while ( my $record = $sb->Next ) {
print $record->my_column_name();
}
DESCRIPTION
This module provides an object-oriented mechanism for retrieving and updating data in a DBI-accesible database.
In order to use this module, you should create a subclass of "DBIx::SearchBuilder" and a subclass of "DBIx::SearchBuilder::Record" for each
table that you wish to access. (See the documentation of "DBIx::SearchBuilder::Record" for more information on subclassing it.)
Your "DBIx::SearchBuilder" subclass must override "NewItem", and probably should override at least "_Init" also; at the very least, "_Init"
should probably call "_Handle" and "_Table" to set the database handle (a "DBIx::SearchBuilder::Handle" object) and table name for the
class. You can try to override just about every other method here, as long as you think you know what you are doing.
METHOD NAMING
Each method has a lower case alias; '_' is used to separate words. For example, the method "RedoSearch" has the alias "redo_search".
METHODS
new
Creates a new SearchBuilder object and immediately calls "_Init" with the same parameters that were passed to "new". If you haven't
overridden "_Init" in your subclass, this means that you should pass in a "DBIx::SearchBuilder::Handle" (or one of its subclasses) like
this:
my $sb = My::DBIx::SearchBuilder::Subclass->new( Handle => $handle );
However, if your subclass overrides _Init you do not need to take a Handle argument, as long as your subclass returns an appropriate handle
object from the "_Handle" method. This is useful if you want all of your SearchBuilder objects to use a shared global handle and don't
want to have to explicitly pass it in each time, for example.
_Init
This method is called by "new" with whatever arguments were passed to "new". By default, it takes a "DBIx::SearchBuilder::Handle" object
as a "Handle" argument, although this is not necessary if your subclass overrides "_Handle".
CleanSlate
This completely erases all the data in the SearchBuilder object. It's useful if a subclass is doing funky stuff to keep track of a search
and wants to reset the SearchBuilder data without losing its own data; it's probably cleaner to accomplish that in a different way, though.
Clone
Returns copy of the current object with all search restrictions.
_ClonedAttributes
Returns list of the object's fields that should be copied.
If your subclass store references in the object that should be copied while clonning then you probably want override this method and add
own values to the list.
_Handle [DBH]
Get or set this object's DBIx::SearchBuilder::Handle object.
_DoSearch
This internal private method actually executes the search on the database; it is called automatically the first time that you actually need
results (such as a call to "Next").
AddRecord RECORD
Adds a record object to this collection.
_RecordCount
This private internal method returns the number of Record objects saved as a result of the last query.
_DoCount
This internal private method actually executes a counting operation on the database; it is used by "Count" and "CountAll".
_ApplyLimits STATEMENTREF
This routine takes a reference to a scalar containing an SQL statement. It massages the statement to limit the returned rows to only
"$self->RowsPerPage" rows, skipping "$self->FirstRow" rows. (That is, if rows are numbered starting from 0, row number "$self->FirstRow"
will be the first row returned.) Note that it probably makes no sense to set these variables unless you are also enforcing an ordering on
the rows (with "OrderByCols", say).
_DistinctQuery STATEMENTREF
This routine takes a reference to a scalar containing an SQL statement. It massages the statement to ensure a distinct result set is
returned.
_BuildJoins
Build up all of the joins we need to perform this query.
_isJoined
Returns true if this SearchBuilder will be joining multiple tables together.
_isLimited
If we've limited down this search, return true. Otherwise, return false.
BuildSelectQuery
Builds a query string for a "SELECT rows from Tables" statement for this SearchBuilder object
BuildSelectCountQuery
Builds a SELECT statement to find the number of rows this SearchBuilder object would find.
Next
Returns the next row from the set as an object of the type defined by sub NewItem. When the complete set has been iterated through,
returns undef and resets the search such that the following call to Next will start over with the first item retrieved from the database.
GotoFirstItem
Starts the recordset counter over from the first item. The next time you call Next, you'll get the first item returned by the database, as
if you'd just started iterating through the result set.
GotoItem
Takes an integer, n. Sets the record counter to n. the next time you call Next, you'll get the nth item.
First
Returns the first item
Last
Returns the last item
DistinctFieldValues
Returns list with distinct values of field. Limits on collection are accounted, so collection should be "UnLimit"ed to get values from the
whole table.
Takes paramhash with the following keys:
Field
Field name. Can be first argument without key.
Order
'ASC', 'DESC' or undef. Defines whether results should be sorted or not. By default results are not sorted.
Max Maximum number of elements to fetch.
ItemsArrayRef
Return a refernece to an array containing all objects found by this search.
NewItem
NewItem must be subclassed. It is used by DBIx::SearchBuilder to create record objects for each row returned from the database.
RedoSearch
Takes no arguments. Tells DBIx::SearchBuilder that the next time it's asked for a record, it should requery the database
UnLimit
UnLimit clears all restrictions and causes this object to return all rows in the primary table.
Limit
Limit takes a hash of parameters with the following keys:
TABLE
Can be set to something different than this table if a join is wanted (that means we can't do recursive joins as for now).
ALIAS
Unless ALIAS is set, the join criterias will be taken from EXT_LINKFIELD and INT_LINKFIELD and added to the criterias. If ALIAS is
set, new criterias about the foreign table will be added.
LEFTJOIN
To apply the Limit inside the ON clause of a previously created left join, pass this option along with the alias returned from creating
the left join. ( This is similar to using the EXPRESSION option when creating a left join but this allows you to refer to the join
alias in the expression. )
FIELD
Column to be checked against.
VALUE
Should always be set and will always be quoted.
OPERATOR
OPERATOR is the SQL operator to use for this phrase. Possible choices include:
"="
"!="
"LIKE"
In the case of LIKE, the string is surrounded in % signs. Yes. this is a bug.
"NOT LIKE"
"STARTSWITH"
STARTSWITH is like LIKE, except it only appends a % at the end of the string
"ENDSWITH"
ENDSWITH is like LIKE, except it prepends a % to the beginning of the string
"MATCHES"
MATCHES is equivalent to the database's LIKE -- that is, it's actually LIKE, but doesn't surround the string in % signs as LIKE
does.
ENTRYAGGREGATOR
Can be "AND" or "OR" (or anything else valid to aggregate two clauses in SQL). Special value is "none" which means that no entry
aggregator should be used. The default value is "OR".
CASESENSITIVE
on some databases, such as postgres, setting CASESENSITIVE to 1 will make this search case sensitive
SUBCLAUSE
Subclause allows you to assign tags to Limit statements. Statements with matching SUBCLAUSE tags will be grouped together in the final
SQL statement.
Example:
Suppose you want to create Limit statments which would produce results the same as the following SQL:
SELECT * FROM Users WHERE EmailAddress OR Name OR RealName OR Email LIKE $query;
You would use the following Limit statements:
$folks->Limit( FIELD => 'EmailAddress', OPERATOR => 'LIKE', VALUE => "$query", SUBCLAUSE => 'groupsearch');
$folks->Limit( FIELD => 'Name', OPERATOR => 'LIKE', VALUE => "$query", SUBCLAUSE => 'groupsearch');
$folks->Limit( FIELD => 'RealName', OPERATOR => 'LIKE', VALUE => "$query", SUBCLAUSE => 'groupsearch');
OrderBy PARAMHASH
Orders the returned results by ALIAS.FIELD ORDER.
Takes a paramhash of ALIAS, FIELD and ORDER. ALIAS defaults to "main". FIELD has no default value. ORDER defaults to ASC(ending).
DESC(ending) is also a valid value for OrderBy.
FIELD also accepts "FUNCTION(FIELD)" format.
OrderByCols ARRAY
OrderByCols takes an array of paramhashes of the form passed to OrderBy. The result set is ordered by the items in the array.
_OrderClause
returns the ORDER BY clause for the search.
GroupByCols ARRAY_OF_HASHES
Each hash contains the keys ALIAS and FIELD. ALIAS defaults to 'main' if ignored.
_GroupClause
Private function to return the "GROUP BY" clause for this query.
NewAlias
Takes the name of a table. Returns the string of a new Alias for that table, which can be used to Join tables or to Limit what gets found
by a search.
Join
Join instructs DBIx::SearchBuilder to join two tables.
The standard form takes a param hash with keys ALIAS1, FIELD1, ALIAS2 and FIELD2. ALIAS1 and ALIAS2 are column aliases obtained from
$self->NewAlias or a $self->Limit. FIELD1 and FIELD2 are the fields in ALIAS1 and ALIAS2 that should be linked, respectively. For this
type of join, this method has no return value.
Supplying the parameter TYPE => 'left' causes Join to preform a left join. in this case, it takes ALIAS1, FIELD1, TABLE2 and FIELD2.
Because of the way that left joins work, this method needs a TABLE for the second field rather than merely an alias. For this type of
join, it will return the alias generated by the join.
Instead of ALIAS1/FIELD1, it's possible to specify EXPRESSION, to join ALIAS2/TABLE2 on an arbitrary expression.
It is also possible to join to a pre-existing, already-limited DBIx::SearchBuilder object, by passing it as COLLECTION2, instead of
providing an ALIAS2 or TABLE2.
Pages: size and changing
Use "RowsPerPage" to set size of pages. "NextPage", "PrevPage", "FirstPage" or "GotoPage" to change pages. "FirstRow" to do tricky stuff.
RowsPerPage
Get or set the number of rows returned by the database.
Takes an optional integer which restricts the # of rows returned in a result. Zero or undef argument flush back to "return all records
matching current conditions".
Returns the current page size.
NextPage
Turns one page forward.
PrevPage
Turns one page backwards.
FirstPage
Jumps to the first page.
GotoPage
Takes an integer number and jumps to that page or first page if number omitted. Numbering starts from zero.
FirstRow
Get or set the first row of the result set the database should return. Takes an optional single integer argrument. Returns the currently
set integer minus one (this is historical issue).
Usually you don't need this method. Use "RowsPerPage", "NextPage" and other methods to walk pages. It only may be helpful to get 10 records
starting from 5th.
_ItemsCounter
Returns the current position in the record set.
Count
Returns the number of records in the set.
CountAll
Returns the total number of potential records in the set, ignoring any "RowsPerPage" settings.
IsLast
Returns true if the current row is the last record in the set.
Column
Call to specify which columns should be loaded from the table. Each calls adds one column to the set. Takes a hash with the following
named arguments:
FIELD
Column name to fetch or apply function to. This can be omitted if a FUNCTION is given which is not a function of a field.
ALIAS
Alias of a table the field is in; defaults to "main"
FUNCTION
A SQL function that should be selected as the result. If a FIELD is provided, then it is inserted into the function according to the
following rules:
o If the text of the function contains a '?' (question mark), then it is replaced with qualified FIELD.
o If the text of the function has no '(' (opening parenthesis), then the qualified FIELD is appended in parentheses to the text.
o Otherwise, the function is inserted verbatim, with no substitution.
If a FIELD is provided and it is in this table (ALIAS is 'main'), then the column named FIELD and can be accessed as usual by accessors:
$articles->Column(FIELD => 'id');
$articles->Column(FIELD => 'Subject', FUNCTION => 'SUBSTR(?, 1, 20)');
my $article = $articles->First;
my $aid = $article->id;
my $subject_prefix = $article->Subject;
Returns the alias used for the column. If FIELD was not provided, or was from another table, then the returned column alias should be
passed to the "_Value" in DBIx::SearchBuilder::Record method to retrieve the column's result:
my $time_alias = $articles->Column(FUNCTION => 'NOW()');
my $article = $articles->First;
my $now = $article->_Value( $time_alias );
Columns LIST
Specify that we want to load only the columns in LIST
Fields TABLE
Return a list of fields in TABLE, lowercased.
TODO: Why are they lowercased?
HasField { TABLE => undef, FIELD => undef }
Returns true if TABLE has field FIELD. Return false otherwise
Table [TABLE]
If called with an argument, sets this collection's table.
Always returns this collection's table.
DEPRECATED METHODS
GroupBy
DEPRECATED. Alias for the "GroupByCols" method.
SetTable
DEPRECATED. Alias for the "Table" method.
ShowRestrictions
DEPRECATED AND DOES NOTHING.
ImportRestrictions
DEPRECATED AND DOES NOTHING.
TESTING
In order to test most of the features of "DBIx::SearchBuilder", you need to provide "make test" with a test database. For each DBI driver
that you would like to test, set the environment variables "SB_TEST_FOO", "SB_TEST_FOO_USER", and "SB_TEST_FOO_PASS" to a database name,
database username, and database password, where "FOO" is the driver name in all uppercase. You can test as many drivers as you like. (The
appropriate "DBD::" module needs to be installed in order for the test to work.) Note that the "SQLite" driver will automatically be
tested if "DBD::Sqlite" is installed, using a temporary file as the database. For example:
SB_TEST_MYSQL=test SB_TEST_MYSQL_USER=root SB_TEST_MYSQL_PASS=foo
SB_TEST_PG=test SB_TEST_PG_USER=postgres make test
AUTHOR
Copyright (c) 2001-2006 Jesse Vincent, jesse@bestpractical.com.
All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
SEE ALSO
DBIx::SearchBuilder::Handle, DBIx::SearchBuilder::Record.
perl v5.14.2 2012-03-26 DBIx::SearchBuilder(3pm)