Thomas Sibley > DBIx-SearchBuilder > DBIx::SearchBuilder

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Module Version: 1.65   Source   Latest Release: DBIx-SearchBuilder-1.66

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.

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.

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