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 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. These fields are in the case presented by the
database, which may be case-sensitive.
HasField { TABLE => undef, FIELD => undef }¶
Returns true if TABLE has field FIELD. Return false otherwise
Note: Both TABLE and FIELD are case-sensitive (See: "Fields")
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¶
Best Practical Solutions, LLC <modules@bestpractical.com>
BUGS¶
All bugs should be reported via email to
L<bug-DBIx-SearchBuilder@rt.cpan.org|mailto:bug-DBIx-SearchBuilder@rt.cpan.org>
or via the web at
L<rt.cpan.org|http://rt.cpan.org/Public/Dist/Display.html?Name=DBIx-SearchBuilder>.
LICENSE AND COPYRIGHT¶
Copyright (C) 2001-2014, Best Practical Solutions LLC.
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.