Reflecting on Service Data Objects
Reflecting on Service Data Objects
Reflecting on Service Data Objects
SDOs have a knowledge of the structure they have
been created to represent (the model). For example, a Company SDO
created using the Company
XML schema above would only be permitted to contain
DepartmentType data objects which in turn could only contain
EmployeeType data objects.
Sometimes it is useful to be able to access this
model information at runtime. For example, this could be used to
automatically generate a user interface for populating a data
object. The model information is accessed using reflection.
Example #1 Reflecting on a Data Object
The following example shows how we can reflect on an empty
Employee data object.
<?php
// Create the employee data object (e.g. from an XML Data Access Service)
$employee = ...;
$reflection = new SDO_Model_ReflectionDataObject($employee);
print($reflection);
?>The above example will output:
object(SDO_Model_ReflectionDataObject)#4 { - ROOT OBJECT - Type {
companyNS:EmployeeType[3] { commonj.sdo:String $name;
commonj.sdo:String $SN; commonj.sdo:Boolean $manager; } }
Using print on the SDO_Model_ReflectionDataObject writes out the
data object’s model. We can see from the output how the type
companyNS:EmployeeType has three properties and we can see the
names of the properties along with their types. Note, the primitive
types are listed as SDO types (e.g. commonj.sdo namespace, String
type). It is worth noting that this is the SDO model and when these
are surfaced to an application they can be treated as the PHP
equivalent types (e.g. string and boolean).
Example #2 Accessing the type information
We can query the type information of a data object using
reflection. The following example checks the type corresponds to a
data object rather than a primitive and then iterates through the
properties of the type, writing out the name of each property
($type and $property are SDO_Model_Type and SDO_Model_Property
objects, respectively).
<?php
// Create the employee data object (e.g. from an XML Data Access Service)
$employee = ...;
$reflection = new SDO_Model_ReflectionDataObject($employee);
$type = $reflection->getType();
if (! $type->isDataType()) {
foreach ($type->getProperties() as $property) {
print $property->getName() . "\n";
}
}
?>The above example will output:
name SN manager