DBIx::SearchBuilder(3)User Contributed Perl DocumentatioDBIx::SearchBuilder(3)NAMEDBIx::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 and sets the record iterator to N. The first time
"Next" is called afterwards, it will return the Nth item found by the
search.
You should only call GotoItem after you've already fetched at least one
result or otherwise forced the search query to run (such as via
"ItemsArrayRef"). If GotoItem is called before the search query is
ever run, it will reset the item iterator and "Next" will return the
"First" 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.
FUNCTION
Function that should be checked against or applied to the FIELD
before check. See "CombineFunctionWithField" for rules.
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.
"IN" and "NOT IN"
VALUE can be an array reference or an object inherited from
this class. If it's not then it's treated as any other operator
and in most cases SQL would be wrong. Values in array are
considered as constants and quoted according to QUOTEVALUE.
If object is passed as VALUE then its select statement is used.
If no "Column" is selected then "id" is used, if more than one
selected then warning is issued and first column is used.
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 FIELD, FUNCTION and ALIAS. Hash combined
into SQL with "CombineFunctionWithField".
_GroupClause
Private function to return the "GROUP BY" clause for this query.
NewAlias
Takes the name of a table and paramhash with TYPE and DISTINCT.
Use TYPE equal to "LEFT" to indicate that it's LEFT JOIN. Old style way
to call (see below) is also supported, but should be avoided:
$records->NewAlias('aTable', 'left');
True DISTINCT value indicates that this join keeps result set distinct
and DB side distinct is not required. See also "Join".
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.
By passing true value as DISTINCT argument join can be marked distinct.
If all joins are distinct then whole query is distinct and
SearchBuilder can avoid "_DistinctQuery" call that can hurt performance
of the query. See also "NewAlias".
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.
ALIAS
Alias of a table the field is in; defaults to "main"
FUNCTION
A SQL function that should be selected instead of FIELD or applied
to it.
AS The column alias to use instead of the default. The default column
alias is either the column's name (i.e. what is passed to FIELD) if
it is in this table (ALIAS is 'main') or an autogenerated alias.
Pass "undef" to skip column aliasing entirely.
"FIELD", "ALIAS" and "FUNCTION" are combined according to
"CombineFunctionWithField".
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 );
To choose the column's alias yourself, pass a value for the AS
parameter (see above). Be careful not to conflict with existing column
aliases.
CombineFunctionWithField
Takes a hash with three optional arguments: FUNCTION, FIELD and ALIAS.
Returns SQL with all three arguments combined according to the
following rules.
· FUNCTION or undef returned when FIELD is not provided
· 'main' ALIAS is used if not provided
· ALIAS.FIELD returned when FUNCTION is not provided
· NULL returned if FUNCTION is 'NULL'
· If FUNCTION contains '?' (question marks) then they are replaced
with ALIAS.FIELD and result returned.
· If FUNCTION has no '(' (opening parenthesis) then ALIAS.FIELD is
appended in parentheses and returned.
Examples:
$obj->CombineFunctionWithField()
=> undef
$obj->CombineFunctionWithField(FUNCTION => 'FOO')
=> 'FOO'
$obj->CombineFunctionWithField(FIELD => 'foo')
=> 'main.foo'
$obj->CombineFunctionWithField(ALIAS => 'bar', FIELD => 'foo')
=> 'bar.foo'
$obj->CombineFunctionWithField(FUNCTION => 'FOO(?, ?)', FIELD => 'bar')
=> 'FOO(main.bar, main.bar)'
$obj->CombineFunctionWithField(FUNCTION => 'FOO', ALIAS => 'bar', FIELD => 'baz')
=> 'FOO(bar.baz)'
$obj->CombineFunctionWithField(FUNCTION => 'NULL', FIELD => 'bar')
=> 'NULL'
Columns LIST
Specify that we want to load only the columns in LIST
AdditionalColumn
Calls "Column", but first ensures that this table's standard columns
are selected as well. Thus, each call to this method results in an
additional column selected instead of replacing the default columns.
Takes a hash of parameters which is the same as "Column". Returns the
result of calling "Column".
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 v5.18.2 2013-07-03 DBIx::SearchBuilder(3)
