&reftitle.examples;

The examples below assume an SDO created with the schema and instance information shown below, using the XML Data Access Service. The instance document below describes a single company, called 'MegaCorp', which contains a single department, called 'Advanced Technologies'. The Advanced Technologies department contains three employees. The company employeeOfTheMonth is referencing the second employee, 'Jane Doe'. ]]> The root element of the schema is a company. The company contains departments, and each department contains employees. Each element has a number of attributes to store things like name, serial number, and so on. Finally, the company also has an IDREF attribute which identifies one of the employees as the 'employeeOfTheMonth'. ]]> The XML Data Access Service maps the schema to an SDO. Attributes such as "name" become primitive properties, the sequence of employees becomes a many-valued containment relationship, and so on. Note that the containment relationships are expressed as one complex type within another, whereas non-containment references are expressed in terms of ID and IDREF, with a special sdoxml:propertyType attribute specifying the type of the non-containment reference.

The following examples assume $company is the root of a tree of data objects created from the schema and instance document shown above. Data object properties can be accessed using the object property access syntax. The following sets the company name to 'Acme'. name = 'Acme'; ?> ]]> We can also access properties using associative array syntax. The simplest form of this uses the property name as the array index. For example, the following sets the company name and gets the employeeOfTheMonth. ]]> We can iterate over the properties of a data object using &foreach;. The following iterates over the properties of the employee of the month. employeeOfTheMonth; foreach ($eotm as $name => $value) { echo "$name: $value\n"; } ?> ]]> which will output: The 'manager' property is not output, because it has not been set. Many-valued data object properties can also be accessed using the object property name syntax. The following gets the list of departments. departments; ?> ]]> We can access individual elements of many-valued properties using array syntax. The following accesses the first department in the company. departments[0]; ?> ]]> Many-valued properties can also be iterated over using &foreach;. The following iterates over the company's departments. departments as $department) { // ... } ?> ]]> Each iteration will assign the next department in the list to the variable $department. We can chain property references on a single line. The following sets and gets the name of the first department. departments[0]->name = 'Emerging Technologies'; $dept_name = $company->departments[0]->name; ?> ]]> Using the associative array syntax, this is equivalent to ]]> In either case, the dept_name variable is set to 'Emerging Technologies'. The associative array index can be an XPath-like expression. Valid expressions are defined by an augmented sub-set of XPath. Two forms of indexing into many-valued properties are supported. The first is the standard XPath array syntax with the indexing starting at one, the second is an SDO extension to XPath with an index starting at zero. The standard syntax is: ]]> and the SDO XPath extension syntax is: ]]> Both these examples get the second employee from the first department. We can use XPath to query and identify parts of a data object based on instance data. The following retrieves the manager from the 'Advanced Technologies' department. ]]> A data object can be a factory for its child data objects. A child data object is automatically part of the data graph. The following add a new employee to the 'Advanced Technologies' department. createDataObject('employees'); $new_hire->name = 'John Johnson'; $new_hire->SN = 'E0005'; $new_hire->manager = false; ?> ]]> We can use the isset and unset functions to test and remove items from the data object. The following clears the name of the first department. departments[0]->name); ?> ]]> unset can also be used to remove a data object from the tree. The following example shows John Jones leaving the company. departments[0]->employees[0]); ?> ]]> The following removes the 'employeeOfTheMonth' from the company. If this were a containment relationship then the employee would be removed from the company (probably not a good idea to sack your best employee each month!), but since this is a non-containment reference, the employee being referenced will remain in the department in the company, but will no longer be accessible via the employeeOfTheMonth property. employeeOfTheMonth)) { unset($company->employeeOfTheMonth); } ?> ]]> Data object properties can be accessed via their property index using array syntax. The property index is the position at which the property's definition appears in the model (in this case the xml schema). We can see from the schema listing above that the company name attribute is the second company property (the SDO interface makes no distinction between XML attributes and elements). The following sets the company name to 'Acme', with the same result as Access via property name ]]> Using the index directly in this way is likely to be fragile. Normally the property name syntax should be preferred, but the property index may be required in special cases.

Sequenced data objects are SDOs which can track property ordering across the properties of a data object. They can also contain unstructured text elements (text element which do not belong to any of the SDO's properties). Sequenced data objects are useful for working with XML documents which allow unstructured text (i.e. mixed=true) or if the elements can be interleaved ( ]]>). This can occur for example when the schema defines maxOccurs>1 on a element which is a complexType with a choice order indicator. The examples below assume an SDO created with the following schema and instance information, using the XML Data Access Service. The schema below describes the format of a letter. The letter can optionally contain three properties; date, firstName, and lastName. The schema states mixed="true" which means that unstructured text can be interspersed between the three properties. ]]> The following is an instance letter document. It contains the three letter properties; date, firstName and lastName, and has unstructured text elements for the address and letter body. March 1, 2005 Mutual of Omaha Wild Kingdom, USA Dear Casy Crocodile Please buy more shark repellent. Your premium is past due. ]]> When loaded, the letter data object will have the sequence and property indices shown in the table below: Sequence Index Property Index:Name Value 0 0:date March 1, 2005 1 - Mutual of Omaha 2 - Wild Kingdom, USA 3 - Dear 4 1:firstName Casy 5 2:lastName Crocodile 6 - Please buy more shark repellent. 7 - Your premium is past due. To ensure sequence indices are maintained, sequenced data objects should be manipulated through the SDO_Sequence interface. This allows the data object's instance data to be manipulated in terms of the sequence index as opposed to the property index (shown in the table above). The following examples assume the letter instance has been loaded into a data object referenced by the variable $letter. We obtain a data object's sequence using the getSequence method. The follow gets the sequence for the letter data object. getSequence(); ?> ]]> All subsequent examples assume that the $letter_seq variable has been assigned the sequence for the letter data object. We can get and set individual values (including unstructured text) using the sequence index. The following sets the firstName to 'Snappy' and gets the last sequence values (the unstructured text, 'Your premium is past due.'). ]]> We can iterate through the individual sequence values using &foreach;. The following runs through the individual values in sequence order. getSequence() as $value) { // ... } ?> ]]> Setting values through the data object interface may result in the value not being part of the sequence. A value set through the data object will only be accessible through the sequence if the property was already part of the sequence. The following example sets the lastName through the data object and gets it through the sequence. This is fine because lastName already exists in the sequence. If it had not previously been set, then lastName would be set to 'Smith', but would not be part of the sequence. ]]> We can add new values to a sequence using the SDO_Sequence::insert method. The following examples assume that the 'firstName' and 'lastName' properties are initially unset. insert('Smith', NULL, 1); // Append a lastName value to the sequence // value: 'Jones' // sequence index: NULL (append) // propertyIdentifier: 'lastName' (lastName property name) $letter_seq->insert('Jones', NULL, 'lastName'); // Append unstructured text // value: 'Cancel Subscription.' // sequence index: absent (append) // propertyIdentifier: absent (unstructured text) $letter_seq->insert('Cancel Subscription.'); // Insert new unstructured text. Subsequent sequence values // are shifted up. // value: 'Care of:' // sequence index: 1 (insert as second element) // propertyIdentifier: absent (unstructured text) $letter_seq->insert('Care of:', 1); ?> ]]> We can use the isset and unset functions to test and remove items from the sequence (Note: unset currently leaves the values in the data object, but this behaviour is likely to change to also remove the data from the data object). A sequence behaves like a contiguous list; therefore, removing items from the middle will shift entries at higher indices down. The following example tests to see if the first sequence element is set and unsets it if is. ]]>

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. The following example shows how we can reflect on an empty Employee data object. ]]> &example.outputs; 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). 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). getType(); if (! $type->isDataType()) { foreach ($type->getProperties() as $property) { print $property->getName() . "\n"; } } ?> ]]> &example.outputs;