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diff --git a/demos/quickstart/protected/pages/Database/ActiveRecord.page b/demos/quickstart/protected/pages/Database/ActiveRecord.page index e3da53c0..a1337ba3 100644 --- a/demos/quickstart/protected/pages/Database/ActiveRecord.page +++ b/demos/quickstart/protected/pages/Database/ActiveRecord.page @@ -2,53 +2,53 @@ <!-- $Id $ --> <h1>Active Record</h1> <p>Active Records are objects that wrap a row in a database table or view, - encapsulates the database access and adds domain logic on that data. - The basics of an Active Record is a business object class, e.g., a - <tt>Products</tt> class, that match very closely the record structure - of an underlying database table. Each Active Record will be responsible for - saving and loading data to and from the database. </p> + encapsulates the database access and adds domain logic on that data. + The basics of an Active Record is a business object class, e.g., a + <tt>Products</tt> class, that match very closely the record structure + of an underlying database table. Each Active Record will be responsible for + saving and loading data to and from the database. </p> <div class="info"><b class="note">Info:</b> - The data structure of an Active Record should match exactly that of a table - in the database. - Each field in the class must correspond to one column in the table. + The data structure of an Active Record should match exactly that of a table + in the database. + Each field in the class must correspond to one column in the table. </div> <h2>When to Use It</h2> <p>Active Record is a good choice for domain logic that isn't too complex, - such as creates, reads, updates, and deletes. Derivations and validations - based on a single record work well in this structure. Active Record has the - primary advantage of simplicity. It's easy to build - Active Records, and they are easy to understand.</p> + such as creates, reads, updates, and deletes. Derivations and validations + based on a single record work well in this structure. Active Record has the + primary advantage of simplicity. It's easy to build + Active Records, and they are easy to understand.</p> - <p>However, as your business logic grows in complexity, you'll soon want - to use your object's direct relationships, collections, inheritance, and so + <p>However, as your business logic grows in complexity, you'll soon want + to use your object's direct relationships, collections, inheritance, and so forth. These don't map easily onto Active Record, and adding them piecemeal - gets very messy. - Another argument against Active Record is the fact that it couples the object - design to the database design. This makes it more difficult to refactor as a project goes forward.</p> - - <p>The alternative is to use a Data Mapper that separates the roles of the - business object and how these objects are stored. - Prado provides a complimentary choice between Active Record and - <a href="?page=Database.SqlMap">SqlMap Data Mapper</a>. - A SqlMap Data Mapper can be used to load Active Record objects, in turn, these - Active Record objects can be used to update the database. - The "relationship" between Active Records and <a href="?page=Database.SqlMap">SqlMap</a> is illustrated in the - following diagram. More details regarding the SqlMap Data Mapper can be found in - the <a href="http://www.pradosoft.com/demos/sqlmap/">SqlMap Manual</a>. - <img src=<%~ sqlmap_active_record.png %> alt="Active Records and SqlMap DataMapper" id="fig:diagram.png" class="figure"/> - </p> - - <p> - The Active Record class has methods that do the following: - <ul> - <li>Construct an instance of the Active Record from a SQL result set row.</li> - <li>Construct a new instance for later insertion into the table.</li> - <li>Finder methods to wrap commonly used SQL queries and return Active Record objects.</li> - <li>Update existing records and insert new records into the database.</li> - </ul> - </p> -The Active Record implementation utilizes the <a href="?page=Database.DAO">Prado DAO</a> classes for data access. + gets very messy. + Another argument against Active Record is the fact that it couples the object + design to the database design. This makes it more difficult to refactor as a project goes forward.</p> + + <p>The alternative is to use a Data Mapper that separates the roles of the + business object and how these objects are stored. + Prado provides a complimentary choice between Active Record and + <a href="?page=Database.SqlMap">SqlMap Data Mapper</a>. + A SqlMap Data Mapper can be used to load Active Record objects, in turn, these + Active Record objects can be used to update the database. + The "relationship" between Active Records and <a href="?page=Database.SqlMap">SqlMap</a> is illustrated in the + following diagram. More details regarding the SqlMap Data Mapper can be found in + the <a href="http://www.pradosoft.com/demos/sqlmap/">SqlMap Manual</a>. + <img src=<%~ sqlmap_active_record.png %> alt="Active Records and SqlMap DataMapper" id="fig:diagram.png" class="figure"/> + </p> + + <p> + The Active Record class has methods that do the following: + <ul> + <li>Construct an instance of the Active Record from a SQL result set row.</li> + <li>Construct a new instance for later insertion into the table.</li> + <li>Finder methods to wrap commonly used SQL queries and return Active Record objects.</li> + <li>Update existing records and insert new records into the database.</li> + </ul> + </p> +The Active Record implementation utilizes the <a href="?page=Database.DAO">Prado DAO</a> classes for data access. The current Active Record implementation supports <a href="http://www.mysql.com">MySQL</a>, <a href="http://www.postgres.com">Postgres SQL</a> and @@ -56,14 +56,14 @@ The current Active Record implementation supports Support for other databases can be provided when there are sufficient demand. <h2>Defining an Active Record</h2> <p>Let us - consider the following "users" table that contains two columns named "username" and "email", - where "username" is also the primary key. + consider the following "users" table that contains two columns named "username" and "email", + where "username" is also the primary key. <com:TTextHighlighter Language="sql" CssClass="source"> CREATE TABLE users ( - username VARCHAR( 20 ) NOT NULL , - email VARCHAR( 200 ) , - PRIMARY KEY ( username ) + username VARCHAR( 20 ) NOT NULL , + email VARCHAR( 200 ) , + PRIMARY KEY ( username ) ); </com:TTextHighlighter> </p> @@ -71,91 +71,98 @@ CREATE TABLE users <com:TTextHighlighter Language="php" CssClass="source"> class UserRecord extends TActiveRecord { - public $username; //the column named "username" in the "users" table - public $email; - - public static $_tablename='users'; //table name - - /** - * @return TActiveRecord active record finder instance - */ - public static function finder() - { - return self::getRecordFinder('UserRecord'); - } + public $username; //the column named "username" in the "users" table + public $email; + + public static $_tablename='users'; //table name + + /** + * @return TActiveRecord active record finder instance + */ + public static function finder() + { + return self::getRecordFinder('UserRecord'); + } } </com:TTextHighlighter> </p> <p>Each property of the <tt>UserRecord</tt> class must correspond to a - column with the same name in the "users" table. The static class variable - <tt>$_tablename</tt> (must be public) is optional when the class name is the same as - the table name in the database, otherwise <tt>$_tablename</tt> must - specify the table name that corresponds to your Active Record class. + column with the same name in the "users" table. The static class variable + <tt>$_tablename</tt> (must be public) is optional when the class name is the same as + the table name in the database, otherwise <tt>$_tablename</tt> must + specify the table name that corresponds to your Active Record class. </p> <div class="tip"><b class="note">Tip:</b> - Since <tt>TActiveRecord</tt> extends <tt>TComponent</tt>, setter and - getter methods can be defined to allow control over how variables - are set and returned. For example, adding a <tt>$level</tt> property to the UserRecord class: + Since <tt>TActiveRecord</tt> extends <tt>TComponent</tt>, setter and + getter methods can be defined to allow control over how variables + are set and returned. For example, adding a <tt>$level</tt> property to the UserRecord class: <com:TTextHighlighter Language="php" CssClass="source"> class UserRecord extends TActiveRecord { - ... //existing definitions as above - - private $_level; - public function setLevel($value) { - $this->_level=TPropertyValue::ensureInteger($value,0); - } - public function getLevel($value){ - return $this->_level; - } + ... //existing definitions as above + + private $_level; + public function setLevel($value) { + $this->_level=TPropertyValue::ensureInteger($value,0); + } + public function getLevel($value){ + return $this->_level; + } } </com:TTextHighlighter> </div> +<div class="note"><b class="note">Note:</b> +<tt>TActiveRecord</tt> can also work with database views by specifying the value <tt>$_tablename</tt> +corresponding to the view name. However, objects returned +from views are read-only, calling the <tt>save()</tt> or <tt>delete()</tt> method +will raise an exception. +</div> + <p> - The static method <tt>finder()</tt> returns an <tt>UserRecord</tt> instance - that can be used to load records from the database. The loading of records - using the finer methods is discuss a little later. The <tt>TActiveRecord::getRecordFinder()</tt> - static method takes the name of the current Active Record class as parameter. + The static method <tt>finder()</tt> returns an <tt>UserRecord</tt> instance + that can be used to load records from the database. The loading of records + using the finer methods is discuss a little later. The <tt>TActiveRecord::getRecordFinder()</tt> + static method takes the name of the current Active Record class as parameter. </p> <h2>Setting up a database connection</h2> <p> - A default database connection for Active Record can be set as follows. - See <a href="?page=Database.DAO">Establishing Database Connection</a> for - futher details regarding creation of database connection in general. + A default database connection for Active Record can be set as follows. + See <a href="?page=Database.DAO">Establishing Database Connection</a> for + futher details regarding creation of database connection in general. <com:TTextHighlighter Language="php" CssClass="source"> //create a connection and give it to the ActiveRecord manager. $dsn = 'pgsql:host=localhost;dbname=test'; //Postgres SQL $conn = new TDbConnection($dsn, 'dbuser','dbpass'); TActiveRecordManager::getInstance()->setDbConnection($conn); -</com:TTextHighlighter> +</com:TTextHighlighter> </p> <p> - The default database connection can also be configured using a <tt><module></tt> - tag in the <a href="?page=Configurations.AppConfig">application.xml</a> - or <a href="?page=Configurations.PageConfig">config.xml</a> as follows. + The default database connection can also be configured using a <tt><module></tt> + tag in the <a href="?page=Configurations.AppConfig">application.xml</a> + or <a href="?page=Configurations.PageConfig">config.xml</a> as follows. <com:TTextHighlighter Language="xml" CssClass="source"> <modules> <module class="System.Data.ActiveRecord.TActiveRecordConfig" EnableCache="true"> <database ConnectionString="pgsql:host=localhost;dbname=test" Username="dbuser" Password="dbpass" /> </module> -</modules> -</com:TTextHighlighter> +</modules> +</com:TTextHighlighter> <div class="tip"><b class="note">Tip:</b> - The <tt>EnableCache</tt> attribute when set to "true" will cache the table - meta data, that is, the table columns names, indexes and constraints are - saved in the cache and reused. You must clear or disable the cache if you - wish to see chanages made to your table definitions. A <a href="?page=Advanced.Performance#6402">cache - module</a> must also be defined for the cache to function. + The <tt>EnableCache</tt> attribute when set to "true" will cache the table + meta data, that is, the table columns names, indexes and constraints are + saved in the cache and reused. You must clear or disable the cache if you + wish to see chanages made to your table definitions. A <a href="?page=Advanced.Performance#6402">cache + module</a> must also be defined for the cache to function. </div> </p> <p>A <tt>ConnectionID</tt> property can be specified with value corresponding - to another <tt>TDataSourceConfig</tt> module configuration's ID value. This allows - the same database connection to be used in other modules such as <a href="?page=Database.SqlMap">SqlMap</a>. + to another <tt>TDataSourceConfig</tt> module configuration's ID value. This allows + the same database connection to be used in other modules such as <a href="?page=Database.SqlMap">SqlMap</a>. <com:TTextHighlighter Language="xml" CssClass="source"> <modules> <module class="System.Data.TDataSourceConfig" ID="db1"> @@ -168,32 +175,52 @@ TActiveRecordManager::getInstance()->setDbConnection($conn); <module class="System.Data.SqlMap.TSqlMapConfig" ConnectionID="db1" ... /> -</modules> -</com:TTextHighlighter> +</modules> +</com:TTextHighlighter> </p> <h2>Loading data from the database</h2> <p> - The <tt>TActiveRecord</tt> class provides many convenient methods to find - records from the database. The simplest is finding records by matching primary keys. - See the <com:DocLink ClassPath="System.Data.ActiveRecord.TActiveRecord" /> for - more details. + The <tt>TActiveRecord</tt> class provides many convenient methods to find + records from the database. The simplest is finding records by matching primary keys. + See the <com:DocLink ClassPath="System.Data.ActiveRecord.TActiveRecord" /> for + more details. </p> - <h3><tt>findByPk()</tt></h3> - <p>Finds one record using only the primary key or composite primary keys. + <h3><tt>findByPk()</tt></h3> + <p>Finds one record using only the primary key or composite primary keys. <com:TTextHighlighter Language="php" CssClass="source"> $finder = UserRecord::finder(); $user = $finder->findByPk($primaryKey); //when the table uses composite keys -$record = $finder->findByPk($key1, $key2, ...); //for composite keys -$record = $finder->findByPk(array($key1, $key2,...)); //same as above +$record = $finder->findByPk($key1, $key2, ...); +$record = $finder->findByPk(array($key1, $key2,...)); </com:TTextHighlighter> </p> + <h3><tt>findAllByPks()</tt></h3> + <p>Finds multiple records using a list of primary keys or composite primary keys. +The following are equivalent for scalar primary keys (primary key consisting of only one column/field). +<com:TTextHighlighter Language="php" CssClass="source"> +$finder = UserRecord::finder(); +$users = $finder->findAllByPk($key1, $key2, ...); +$users = $finder->findAllByPk(array($key1, $key2, ...)); +</com:TTextHighlighter> +The following are equivalent for composite keys. +<com:TTextHighlighter Language="php" CssClass="source"> +//when the table uses composite keys +$record = $finder->findAllByPks(array($key1, $key2), array($key3, $key4), ...); + +$keys = array( array($key1, $key2), array($key3, $key4), ... ); +$record = $finder->findAllByPks($keys); + +</com:TTextHighlighter> +</p> + + <h3><tt>find()</tt></h3> <p>Finds <b>one single record</b> that matches the criteria. The criteria - can be a partial SQL string or a <tt>TActiveRecordCriteria</tt> object. + can be a partial SQL string or a <tt>TActiveRecordCriteria</tt> object. <com:TTextHighlighter Language="php" CssClass="source"> $finder = UserRecord::finder(); @@ -212,13 +239,13 @@ $finder->find($criteria); //the 2nd parameter for find() is ignored. </p> <p>The <tt>TActiveRecordCriteria</tt> class has the following properties: - <ul> - <li><tt>Parameters</tt> -- name value parameter pairs.</li> - <li><tt>OrderBy</tt> -- column name and ordering pairs.</li> - <li><tt>Condition</tt> -- parts of the WHERE SQL conditions.</li> - <li><tt>Limit</tt> -- maximum number of records to return.</li> - <li><tt>Offset</tt> -- record offset in the table.</li> - </ul> + <ul> + <li><tt>Parameters</tt> -- name value parameter pairs.</li> + <li><tt>OrderBy</tt> -- column name and ordering pairs.</li> + <li><tt>Condition</tt> -- parts of the WHERE SQL conditions.</li> + <li><tt>Limit</tt> -- maximum number of records to return.</li> + <li><tt>Offset</tt> -- record offset in the table.</li> + </ul> </p> <com:TTextHighlighter Language="php" CssClass="source"> @@ -258,8 +285,8 @@ $finder->find('Username = ? AND Password = ?', $name, $pass); $finder->findAllByAge($age); $finder->findAll('Age = ?', $age); </com:TTextHighlighter> -</p> - +</p> + <h3><tt>findBySql()</tt></h3> <p>Finds records using full SQL, returns corresponding array of record objects.</p> @@ -291,7 +318,7 @@ incremented values.</div> <p> To update a record in the database, just change one or more properties of the Active Record object that has been loaded from the database and then -call the <tt>save()</tt> method. +call the <tt>save()</tt> method. <com:TTextHighlighter Language="php" CssClass="source"> $user = UserRecord::finder()->findByName('admin'); @@ -303,14 +330,23 @@ $user->save(); //update it. <p> Active Record objects have a simple life-cycle illustrated in the following diagram. <img src=<%~ object_states.png %> alt="Active Records Life Cycle" id="fig:cycle.png" class="figure"/> +We see that new ActiveRecord objects are created by either using one of the <tt>find*()</tt> +methods or using creating a new instance by using PHP's <tt>new</tt> keyword. Objects +created by a <tt>find*()</tt> method starts with <tt>clean</tt> state. New instance of +ActiveRecords created other than by a <tt>find*()</tt> method starts with <tt>new</tt> state. +When ever you +call the <tt>save()</tt> method on the ActiveRecord object, the object enters the <tt>clean</tt> +state. Objects in the <tt>clean</tt> becomes <tt>dirty</tt> whenever one of more of its +internal states are changed. Calling the <tt>delete()</tt> method on the object +ends the object life-cycle, no futher actions can be performed on the object. </p> <h2>Deleting existing records</h2> <p> - To delete an existing record that is already loaded, just call the <tt>delete()</tt> method. - You can also delete records in the database by primary keys without - loading any records using the <tt>deleteByPk()</tt> method. - For example, to delete one or records with tables having a scalar primary key. + To delete an existing record that is already loaded, just call the <tt>delete()</tt> method. + You can also delete records in the database by primary keys without + loading any records using the <tt>deleteByPk()</tt> method. + For example, to delete one or records with tables having a scalar primary key. <com:TTextHighlighter Language="php" CssClass="source"> $finder->deleteByPk($primaryKey); //delete 1 record $finder->deleteByPk($key1,$key2,...); //delete multiple records @@ -333,7 +369,7 @@ $finder->deleteByPk(array( array($key1,$key2), array($key3,$key4), .. )); <h2>Transactions</h2> <p>All Active Record objects contains the property <tt>DbConnection</tt> - that can be used to obtain a transaction object. + that can be used to obtain a transaction object. <com:TTextHighlighter Language="php" CssClass="source"> $finder = UserRecord::finder(); @@ -345,7 +381,7 @@ try $user->save(); $transaction->commit(); } -catch(Exception $e) // an exception is raised if a query fails will be raised +catch(Exception $e) // an exception is raised if a query fails { $transaction->rollBack(); } @@ -353,8 +389,8 @@ catch(Exception $e) // an exception is raised if a query fails will be raised <h2>References</h2> <ul> - <li>Fowler et. al. <i>Patterns of Enterprise Application Architecture</i>, - Addison Wesley, 2002.</li> + <li>Fowler et. al. <i>Patterns of Enterprise Application Architecture</i>, + Addison Wesley, 2002.</li> </ul> </com:TContent>
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