When you run a query against a Table class using the find() or fetchAll()
methods, the result is returned in an object of type Zend_Db_Table_Rowset_Abstract. A Rowset
contains a collection of objects descending from Zend_Db_Table_Row_Abstract. You can iterate
through the Rowset and access individual Row objects, reading or modifying data in the Rows.
Zend_Db_Table_Abstract provides methods find() and fetchAll(), each
of which returns an object of type Zend_Db_Table_Rowset_Abstract.
The Rowset itself is usually less interesting than the Rows that it contains. This section illustrates how to get the Rows that comprise the Rowset.
A legitimate query returns zero rows when no rows in the database match the query conditions. Therefore, a
Rowset object might contain zero Row objects. Since Zend_Db_Table_Rowset_Abstract implements
the Countable interface, you can use count() to determine the number of Rows in
the Rowset.
Beispiel 9.110. Counting the Rows in a Rowset
<?php
$rowset = $bugs->fetchAll("bug_status = 'FIXED'");
$rowCount = count($rowset);
if ($rowCount > 0) {
echo "found $rowCount rows";
} else {
echo 'no rows matched the query';
}
?>
Beispiel 9.111. Reading a Single Row from a Rowset
The simplest way to access a Row from a Rowset is to use the current() method. This is
particularly appropriate when the Rowset contains exactly one Row.
<?php
$bugs = new Bugs();
$rowset = $bugs->fetchAll("bug_id = 1");
$row = $rowset->current();
?>
If the Rowset contains zero rows, current() returns
PHP's null value.
Beispiel 9.112. Iterating through a Rowset
Objects descending from Zend_Db_Table_Rowset_Abstract implement the Iterator
interface, which means you can loop through them using the foreach construct. Each value
you retrieve this way is a Zend_Db_Table_Row_Abstract object that corresponds to one
record from the table.
<?php
$bugs = new Bugs();
// fetch all records from the table
$rowset = $bugs->fetchAll();
foreach ($rowset as $row) {
// output 'Zend_Db_Table_Row' or similar
echo get_class($row) . "\n";
// read a column in the row
$status = $row->bug_status;
// modify a column in the current row
$row->assigned_to = 'mmouse';
// write the change to the database
$row->save();
}
?>
After you have access to an individual Row object, you can manipulate the Row using methods described in Abschnitt 9.6, „Zend_Db_Table_Row“.
You can access all the data in the Rowset as an array using the toArray() method of the Rowset
object. This returns an array containing one entry per Row. Each entry is an associative array having keys
that correspond to column names and elements that correspond to the respective column values.
Beispiel 9.113. Using toArray()
<?php
$bugs = new Bugs();
$rowset = $bugs->fetchAll();
$rowsetArray = $rowset->toArray();
$rowCount = 1;
foreach ($rowsetArray as $rowArray) {
echo "row #$rowCount:\n";
foreach ($rowArray as $column => $value) {
echo "\t$column => $value\n";
}
++$rowCount;
echo "\n";
}
?>
The array returned from toArray() is not updateable. That is, you can modify values in the
array as you can with any array, but changes to the array data are not propagated to the database.
Objects of type Zend_Db_Table_Rowset_Abstract are serializable. In a similar fashion to
serializing an individual Row object, you can serialize a Rowset and unserialize it later.
Beispiel 9.114. Serializing a Rowset
Simply use PHP's serialize() function to create a string containing a byte-stream
representation of the Rowset object argument.
<?php $bugs = new Bugs(); $rowset = $bugs->fetchAll(); // Convert object to serialized form $serializedRowset = serialize($rowset); // Now you can write $serializedRowset to a file, etc. ?>
Beispiel 9.115. Unserializing a Serialized Rowset
Use PHP's unserialize() function to restore a string containing a byte-stream
representation of an object. The function returns the original object.
Note that the Rowset object returned is in a disconnected state. You can iterate through the Rowset and read the Row objects and their properties, but you cannot change values in the Rows or execute other methods that require a database connection (for example, queries against related tables).
<?php $rowsetDisconnected = unserialize($serializedRowset); // Now you can use object methods and properties, but read-only $row = $rowsetDisconnected->current(); echo $row->bug_description; ?>
![[Anmerkung]](images/note.png) |
Why do Rowsets unserialize in a disconnected state? |
|---|---|
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. |
You can reactivate a disconnected Rowset using the setTable() 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 Rowset, the
Rowset gains access to the database. Subsequently, you can change values in the Row objects contained in
the Rowset and save the changes to the database.
Beispiel 9.116. Reactivating a Rowset as Live Data
<?php $rowset = unserialize($serializedRowset); $bugs = new Bugs(); // Reconnect the rowset to a table, and // thus to a live database connection $rowset->setTable($bugs); $row = $rowset->current(); // Now you can make changes to the row and save them $row->bug_status = 'FIXED'; $row->save(); ?>
Reactivating a Rowset with setTable() also reactivates all the Row objects contained in that
Rowset.
You can use an alternative concrete class for instances of Rowsets
by extending Zend_Db_Table_Rowset_Abstract. Specify the custom
Rowset class by name either in the $_rowsetClass
protected member of a Table class, or in the array argument of the
constructor of a Table object.
Beispiel 9.117. Specifying a custom Rowset class
<?php
class MyRowset extends Zend_Db_Table_Rowset_Abstract
{
// ...customizations
}
// Specify a custom Rowset to be used by default
// in all instances of a Table class.
class Products extends Zend_Db_Table_Abstract
{
protected $_name = 'products';
protected $_rowsetClass = 'MyRowset';
}
// Or specify a custom Rowset to be used in one
// instance of a Table class.
$bugs = new Bugs(array('rowsetClass' => 'MyRowset'));
?>
Typically, the standard Zend_Db_Rowset concrete class is sufficient for most usage. However, you might find it useful to add new logic to a Rowset, specific to a given Table. For example, a new method could calculate an aggregate over all the Rows in the Rowset.
Beispiel 9.118. Example of Rowset class with a new method
<?php
class MyBugsRowset extends Zend_Db_Table_Rowset_Abstract
{
/**
* Find the Row in the current Rowset with the
* greatest value in its 'updated_at' column.
*/
public function getLatestUpdatedRow()
{
$max_updated_at = 0;
$latestRow = null;
foreach ($this as $row) {
if ($row->updated_at > $max_updated_at) {
$latestRow = $row;
}
}
return $latestRow;
}
}
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
protected $_rowsetClass = 'MyBugsRowset';
}
?>