repo_zf1/documentation/manual/es/module_specs/Zend_Db_Table_Row.xml

<sect1 id="zend.db.table.row">

    <title>Zend_Db_Table_Row</title>

    <sect2 id="zend.db.table.row.introduction">

        <title>Introduction</title>

        <para>
            Zend_Db_Table_Row is a class that contains an individual row of a Zend_Db_Table object.
            When you run a query against a Table class, the result is returned in a set of
            Zend_Db_Table_Row objects. You can also use this object to create new rows and add them
            to the database table.
        </para>

        <para>
            Zend_Db_Table_Row is an implementation of the <ulink
            url="http://www.martinfowler.com/eaaCatalog/rowDataGateway.html">Row Data Gateway</ulink>
            pattern.
        </para>

    </sect2>

    <sect2 id="zend.db.table.row.read">

        <title>Fetching a Row</title>

        <para>
            Zend_Db_Table_Abstract provides methods <code>find()</code> and
            <code>fetchAll()</code>, which each return an object of type Zend_Db_Table_Rowset, and
            the method <code>fetchRow()</code>, which returns an object of type Zend_Db_Table_Row.
        </para>

        <example id="zend.db.table.row.read.example">

            <title>Example of fetching a row</title>

            <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow($bugs->select()->where('bug_id = ?', 1));
]]>
            </programlisting>

        </example>

        <para>
            A Zend_Db_Table_Rowset object contains a collection of Zend_Db_Table_Row objects. See
            <xref linkend="zend.db.table.rowset" />.
        </para>

        <example id="zend.db.table.row.read.example-rowset">

            <title>Example of reading a row in a rowset</title>

            <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$rowset = $bugs->fetchAll($bugs->select()->where('bug_status = ?', 1));
$row = $rowset->current();
]]>
            </programlisting>

        </example>

        <sect3 id="zend.db.table.row.read.get">

            <title>Reading column values from a row</title>

            <para>
                Zend_Db_Table_Row_Abstract provides accessor methods so you can reference columns
                in the row as object properties.
            </para>

            <example id="zend.db.table.row.read.get.example">

                <title>Example of reading a column in a row</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow($bugs->select()->where('bug_id = ?', 1));

// Echo the value of the bug_description column
echo $row->bug_description;
]]>
                </programlisting>

            </example>

            <note>

                <para>
                    Earlier versions of Zend_Db_Table_Row mapped these column accessors to the
                    database column names using a string transformation called
                    <emphasis>inflection</emphasis>.
                </para>

                <para>
                    Currently, Zend_Db_Table_Row does not implement inflection. Accessed property
                    names need to match the spelling of the column names as they appear in your
                    database.
                </para>

            </note>

        </sect3>

        <sect3 id="zend.db.table.row.read.to-array">

            <title>Retrieving Row Data as an Array</title>

            <para>
                You can access the row's data as an array using the <code>toArray()</code> method
                of the Row object. This returns an associative array of the column names to the
                column values.
            </para>

            <example id="zend.db.table.row.read.to-array.example">

                <title>Example of using the toArray() method</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow($bugs->select()->where('bug_id = ?', 1));

// Get the column/value associative array from the Row object
$rowArray = $row->toArray();

// Now use it as a normal array
foreach ($rowArray as $column => $value) {
    echo "Column: $column\n";
    echo "Value:  $value\n";
}
]]>
                </programlisting>

            </example>

            <para>
                The array returned from <code>toArray()</code> is not updateable. You can modify
                values in the array as you can with any array, but you cannot save changes to this
                array to the database directly.
            </para>

        </sect3>

        <sect3 id="zend.db.table.row.read.relationships">

            <title>Fetching data from related tables</title>

            <para>
                The Zend_Db_Table_Row_Abstract class provides methods for fetching rows and rowsets
                from related tables. See <xref linkend="zend.db.table.relationships" /> for more
                information on table relationships.
            </para>

        </sect3>

    </sect2>

    <sect2 id="zend.db.table.row.write">

        <title>Writing rows to the database</title>

        <sect3 id="zend.db.table.row.write.set">

            <title>Changing column values in a row</title>

            <para>
                You can set individual column values using column accessors, similar to how the
                columns are read as object properties in the example above.
            </para>

            <para>
                Using a column accessor to set a value changes the column value of the row object
                in your application, but it does not commit the change to the database yet. You can
                do that with the <code>save()</code> method.
            </para>

            <example id="zend.db.table.row.write.set.example">

                <title>Example of changing a column in a row</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow($bugs->select()->where('bug_id = ?', 1));

// Change the value of one or more columns
$row->bug_status = 'FIXED';

// UPDATE the row in the database with new values
$row->save();
]]>
                </programlisting>

            </example>

        </sect3>

        <sect3 id="zend.db.table.row.write.insert">

            <title>Inserting a new row</title>

            <para>
                You can create a new row for a given table with the <code>createRow()</code> method
                of the table class. You can access fields of this row with the object-oriented
                interface, but the row is not stored in the database until you call the
                <code>save()</code> method.
            </para>

            <example id="zend.db.table.row.write.insert.example">

                <title>Example of creating a new row for a table</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$newRow = $bugs->createRow();

// Set column values as appropriate for your application
$newRow->bug_description = '...description...';
$newRow->bug_status = 'NEW';

// INSERT the new row to the database
$newRow->save();
]]>
                </programlisting>

            </example>

            <para>
                The optional argument to the createRow() method is an associative array, with which
                you can populate fields of the new row.
            </para>

            <example id="zend.db.table.row.write.insert.example2">

                <title>Example of populating a new row for a table</title>

                <programlisting role="php"><![CDATA[
$data = array(
    'bug_description' => '...description...',
    'bug_status'      => 'NEW'
);

$bugs = new Bugs();
$newRow = $bugs->createRow($data);

// INSERT the new row to the database
$newRow->save();
]]>
                </programlisting>

            </example>

            <note>

                <para>
                    The <code>createRow()</code> method was called <code>fetchNew()</code> in
                    earlier releases of Zend_Db_Table. You are encouraged to use the new method
                    name, even though the old name continues to work for the sake of backward
                    compatibility.
                </para>

            </note>

        </sect3>

        <sect3 id="zend.db.table.row.write.set-from-array">

            <title>Changing values in multiple columns</title>

            <para>
                Zend_Db_Table_Row_Abstract provides the <code>setFromArray()</code> method to
                enable you to set several columns in a single row at once, specified in an
                associative array that maps the column names to values. You may find this method
                convenient for setting values both for new rows and for rows you need to update.
            </para>

            <example id="zend.db.table.row.write.set-from-array.example">

                <title>Example of using setFromArray() to set values in a new Row</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$newRow = $bugs->createRow();

// Data are arranged in an associative array
$data = array(
    'bug_description' => '...description...',
    'bug_status'      => 'NEW'
);

// Set all the column values at once
$newRow->setFromArray($data);

// INSERT the new row to the database
$newRow->save();
]]>
                </programlisting>

            </example>

        </sect3>

        <sect3 id="zend.db.table.row.write.delete">

            <title>Deleting a row</title>

            <para>
                You can call the <code>delete()</code> method on a Row object. This deletes rows in
                the database matching the primary key in the Row object.
            </para>

            <example id="zend.db.table.row.write.delete.example">

                <title>Example of deleting a row</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow('bug_id = 1');

// DELETE this row
$row->delete();
]]>
                </programlisting>

            </example>

            <para>
                You do not have to call <code>save()</code> to apply the delete; it is executed
                against the database immediately.
            </para>

        </sect3>

    </sect2>

    <sect2 id="zend.db.table.row.serialize">

        <title>Serializing and unserializing rows</title>

        <para>
            It is often convenient to save the contents of a database row to be used later.
            <emphasis>Serialization</emphasis> is the name for the operation that converts an
            object into a form that is easy to save in offline storage (for example, a file).
            Objects of type Zend_Db_Table_Row_Abstract are serializable.
        </para>

        <sect3 id="zend.db.table.row.serialize.serializing">

            <title>Serializing a Row</title>

            <para>
                Simply use PHP's <code>serialize()</code> function to create a string containing a
                byte-stream representation of the Row object argument.
            </para>

            <example id="zend.db.table.row.serialize.serializing.example">

                <title>Example of serializing a row</title>

                <programlisting role="php"><![CDATA[
$bugs = new Bugs();
$row = $bugs->fetchRow('bug_id = 1');

// Convert object to serialized form
$serializedRow = serialize($row);

// Now you can write $serializedRow to a file, etc.
]]>
                </programlisting>

            </example>

        </sect3>

        <sect3 id="zend.db.table.row.serialize.unserializing">

            <title>Unserializing Row Data</title>

            <para>
                Use PHP's <code>unserialize()</code> function to restore a string containing a
                byte-stream representation of an object. The function returns the original object.
            </para>

            <para>
                Note that the Row object returned is in a <emphasis>disconnected</emphasis> state.
                You can read the Row object and its properties, but you cannot change values in the
                Row or execute other methods that require a database connection (for example,
                queries against related tables).
            </para>

            <example id="zend.db.table.row.serialize.unserializing.example">

                <title>Example of unserializing a serialized row</title>

                <programlisting role="php"><![CDATA[
$rowClone = unserialize($serializedRow);

// Now you can use object properties, but read-only
echo $rowClone->bug_description;
]]>
                </programlisting>

            </example>

            <note>

                <title>Why do Rows unserialize in a disconnected state?</title>

                <para>
                    A serialized object is a string that is readable to anyone who possesses it. It
                    could be a security risk to store parameters such as database account and
                    password in plain, unencrypted text in the serialized string. You would not
                    want to store such data to a text file that is not protected, or send it in an
                    email or other medium that is easily read by potential attackers. The reader of
                    the serialized object should not be able to use it to gain access to your
                    database without knowing valid credentials.
                </para>

            </note>

        </sect3>

        <sect3 id="zend.db.table.row.serialize.set-table">

            <title>Reactivating a Row as Live Data</title>

            <para>
                You can reactivate a disconnected Row, using the <code>setTable()</code> method.
                The argument to this method is a valid object of type Zend_Db_Table_Abstract, which
                you create. Creating a Table object requires a live connection to the database, so
                by reassociating the Table with the Row, the Row gains access to the database.
                Subsequently, you can change values in the Row object and save the changes to the
                database.
            </para>

            <example id="zend.db.table.row.serialize.set-table.example">

                <title>Example of reactivating a row</title>

                <programlisting role="php"><![CDATA[
$rowClone = unserialize($serializedRow);

$bugs = new Bugs();

// Reconnect the row to a table, and
// thus to a live database connection
$rowClone->setTable($bugs);

// Now you can make changes to the row and save them
$rowClone->bug_status = 'FIXED';
$rowClone->save();
]]>
                </programlisting>

            </example>

        </sect3>

    </sect2>

    <sect2 id="zend.db.table.row.extending">

        <title>Extending the Row class</title>

        <para>
            Zend_Db_Table_Row is the default concrete class that extends
            Zend_Db_Table_Row_Abstract. You can define your own concrete class for instances of Row
            by extending Zend_Db_Table_Row_Abstract. To use your new Row class to store results of
            Table queries, specify the custom Row class by name either in the
            <code>$_rowClass</code> protected member of a Table class, or in the array argument of
            the constructor of a Table object.
        </para>

        <example id="zend.db.table.row.extending.example">

            <title>Specifying a custom Row class</title>

            <programlisting role="php"><![CDATA[
class MyRow extends Zend_Db_Table_Row_Abstract
{
    // ...customizations
}

// Specify a custom Row to be used by default
// in all instances of a Table class.
class Products extends Zend_Db_Table_Abstract
{
    protected $_name = 'products';
    protected $_rowClass = 'MyRow';
}

// Or specify a custom Row to be used in one
// instance of a Table class.
$bugs = new Bugs(array('rowClass' => 'MyRow'));
]]>
            </programlisting>

        </example>

        <sect3 id="zend.db.table.row.extending.overriding">

            <title>Row initialization</title>

            <para>
                If application-specific logic needs to be initialized when a row is constructed,
                you can select to move your tasks to the <code>init()</code> method, which is
                called after all row metadata has been processed. This is recommended over the
                <code>__construct</code> method if you do not need to alter the metadata in any
                programmatic way.

                <example id="zend.db.table.row.init.usage.example">

                    <title>Example usage of init() method</title>

                    <programlisting role="php"><![CDATA[
class MyApplicationRow extends Zend_Db_Table_Row_Abstract
{
    protected $_role;

    public function init()
    {
        $this->_role = new MyRoleClass();
    }
}
]]>
                    </programlisting>

                </example>

            </para>

        </sect3>

        <sect3 id="zend.db.table.row.extending.insert-update">

            <title>Defining Custom Logic for Insert, Update, and Delete in Zend_Db_Table_Row</title>

            <para>
                The Row class calls protected methods <code>_insert()</code>,
                <code>_update()</code>, and <code>_delete()</code> before performing the
                corresponding operations <code>INSERT</code>, <code>UPDATE</code>, and
                <code>DELETE</code>. You can add logic to these methods in your custom Row
                subclass.
            </para>

            <para>
                If you need to do custom logic in a specific table, and the custom logic must occur
                for every operation on that table, it may make more sense to implement your custom
                code in the <code>insert()</code>, <code>update()</code> and <code>delete()</code>
                methods of your Table class. However, sometimes it may be necessary to do custom
                logic in the Row class.
            </para>

            <para>
                Below are some example cases where it might make sense to implement custom logic in
                a Row class instead of in the Table class:
            </para>

            <example id="zend.db.table.row.extending.overriding-example1">

                <title>Example of custom logic in a Row class</title>

                <para>
                    The custom logic may not apply in all cases of operations on the respective
                    Table. You can provide custom logic on demand by implementing it in a Row class
                    and creating an instance of the Table class with that custom Row class
                    specified. Otherwise, the Table uses the default Row class.
                </para>

                <para>
                    You need data operations on this table to record the operation to a
                    Zend_Log object, but only if the application configuration has enabled this
                    behavior.
                </para>

                <programlisting role="php"><![CDATA[
class MyLoggingRow extends Zend_Db_Table_Row_Abstract
{
    protected function _insert()
    {
        $log = Zend_Registry::get('database_log');
        $log->info(Zend_Debug::dump($this->_data,
                                    "INSERT: $this->_tableClass",
                                    false)
                  );
    }
}

// $loggingEnabled is an example property that depends
// on your application configuration
if ($loggingEnabled) {
    $bugs = new Bugs(array('rowClass' => 'MyLoggingRow'));
} else {
    $bugs = new Bugs();
}
]]>
                </programlisting>

            </example>

            <example id="zend.db.table.row.extending.overriding-example2">

                <title>Example of a Row class that logs insert data for multiple tables</title>

                <para>
                    The custom logic may be common to multiple tables. Instead of implementing the
                    same custom logic in every one of your Table classes, you can implement the
                    code for such actions in the definition of a Row class, and use this Row in
                    each of your Table classes.
                </para>

                <para>
                    In this example, the logging code is identical in all table classes.
                </para>

                <programlisting role="php"><![CDATA[
class MyLoggingRow extends Zend_Db_Table_Row_Abstract
{
    protected function _insert()
    {
        $log = Zend_Registry::get('database_log');
        $log->info(Zend_Debug::dump($this->_data,
                                    "INSERT: $this->_tableClass",
                                    false)
                  );
    }
}

class Bugs extends Zend_Db_Table_Abstract
{
    protected $_name = 'bugs';
    protected $_rowClass = 'MyLoggingRow';
}

class Products extends Zend_Db_Table_Abstract
{
    protected $_name = 'products';
    protected $_rowClass = 'MyLoggingRow';
}
]]>
                </programlisting>

            </example>

        </sect3>

        <sect3 id="zend.db.table.row.extending.inflection">

            <title>Define Inflection in Zend_Db_Table_Row</title>

            <para>
                Some people prefer that the table class name match a table name in the RDBMS by
                using a string transformation called <emphasis>inflection</emphasis>.
            </para>

            <para>
                Zend_Db classes do not implement inflection by default. See
                <xref linkend="zend.db.table.extending.inflection" /> for an explanation of this
                policy.
            </para>

            <para>
                If you prefer to use inflection, then you must implement the transformation yourself,
                by overriding the <code>_transformColumn()</code> method in a custom Row class, and
                using that custom Row class when you perform queries against your Table class.
            </para>

            <example id="zend.db.table.row.extending.inflection.example">

                <title>Example of defining an inflection transformation</title>

                <para>
                    This allows you to use an inflected version of the column name in the
                    accessors. The Row class uses the <code>_transformColumn()</code> method to
                    change the name you use to the native column name in the database table.
                </para>

                <programlisting role="php"><![CDATA[
class MyInflectedRow extends Zend_Db_Table_Row_Abstract
{
    protected function _transformColumn($columnName)
    {
        $nativeColumnName = myCustomInflector($columnName);
        return $nativeColumnName;
    }
}

class Bugs extends Zend_Db_Table_Abstract
{
    protected $_name = 'bugs';
    protected $_rowClass = 'MyInflectedRow';
}

$bugs = new Bugs();
$row = $bugs->fetchNew();

// Use camelcase column names, and rely on the
// transformation function to change it into the
// native representation.
$row->bugDescription = 'New description';
]]>
                </programlisting>

            </example>

            <para>
                You are responsible for writing the functions to perform inflection transformation.
                Zend Framework does not provide such a function.
            </para>

        </sect3>

    </sect2>

</sect1>
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