1. Overview
      1. What It Is
      2. Why I Would Want to Use It
      3. Known Issues
    2. Getting Started
      1. Fundamentals
        1. Design Patterns
        2. xPDO, the Class
          1. As Object and Relational Mapper
          2. As PDO Wrapper
          3. As Service Layer
          4. The xPDO Constructor
            1. Hydrating Fields
      2. Introduction to the xPDO Object Model
        1. Understanding xPDOCriteria and xPDOQuery
      3. Creating a Model With xPDO
        1. Defining a Schema
          1. Defining Relationships
          2. Defining the Database and Tables
            1. Upgrading Models to Schema Version 1.1
          3. More Examples of xPDO XML Schema Files
          4. Validation Rules in your Schema
        2. Generating the Model Code
          1. Domain Classes
          2. O-R Maps
          3. Table Classes
      4. Using Your xPDO Model
        1. Creating Objects
        2. Database Connections and xPDO
        3. Loading Packages
        4. Removing Objects
          1. removeCollection
        5. Retrieving Objects
          1. getCollectionGraph
        6. Setting Object Fields
        7. Working with Related Objects
    3. Extending Your xPDO Model
      1. Overriding Derived Behavior
        1. Using Custom Object Loaders
      2. Working With Transient Object Classes
    4. Advanced Features
      1. Caching
        1. Caching Tutorial - Basic Snippets
        2. Caching Tutorial - Lifetimes
      2. Object Validation
        1. xPDOForeignKeyConstraint
        2. xPDOMaxLengthValidationRule
        3. xPDOMaxValueValidationRule
        4. xPDOMinLengthValidationRule
        5. xPDOMinValueValidationRule
        6. xPDOObjectExistsValidationRule
    5. xPDO Development
      1. Testing
      2. Building
      3. Documentation and Tutorials
    6. Class Reference
      1. xPDO
        1. xPDO.addPackage
        2. xPDO.beginTransaction
        3. xPDO.commit
        4. xPDO.connect
        5. xPDO.fromJSON
        6. xPDO.getCollection
        7. xPDO.getCollectionGraph
        8. xPDO.getCount
        9. xPDO.getDebug
        10. xPDO.getFields
        11. xPDO.getIterator
        12. xPDO.getManager
        13. xPDO.getObject
        14. xPDO.getObjectGraph
        15. xPDO.getOption
        16. xPDO.getTableName
        17. xPDO.loadClass
        18. xPDO.log
        19. xPDO.newObject
        20. xPDO.newQuery
        21. xPDO.query
        22. xPDO.setDebug
        23. xPDO.setLogLevel
        24. xPDO.setLogTarget
        25. xPDO.setOption
        26. xPDO.toJSON
      2. xPDOCacheManager
        1. xPDOCacheManager.copyFile
        2. xPDOCacheManager.copyTree
        3. xPDOCacheManager.delete
        4. xPDOCacheManager.deleteTree
        5. xPDOCacheManager.endsWith
        6. xPDOCacheManager.escapeSingleQuotes
        7. xPDOCacheManager.get
        8. xPDOCacheManager.getCachePath
        9. xPDOCacheManager.getCacheProvider
        10. xPDOCacheManager.matches
        11. xPDOCacheManager.replace
        12. xPDOCacheManager.set
        13. xPDOCacheManager.writeFile
        14. xPDOCacheManager.writeTree
      3. xPDOGenerator
        1. xPDOGenerator.parseSchema
        2. xPDOGenerator.writeSchema
      4. xPDOManager
        1. xPDOManager.createObjectContainer
        2. xPDOManager.createSourceContainer
        3. xPDOManager.removeObjectContainer
        4. xPDOManager.removeSourceContainer
      5. xPDOObject
        1. Configuration Accessors
          1. getOption
          2. setOption
        2. Field Accessors
          1. fromArray
          2. fromJSON
          3. get
          4. set
          5. toArray
          6. toJSON
        3. Metadata Accessors
          1. getFieldName
          2. getFKClass
          3. getFKDefinition
          4. getPK
          5. getPKType
          6. getSelectColumns
        4. Persistence Methods
          1. remove
          2. save
        5. Related Object Accessors
          1. addMany
          2. addOne
          3. getMany
          4. getOne
        6. State Accessors
          1. isDirty
          2. isLazy
          3. isNew
        7. Static Object Loaders
          1. _loadCollectionInstance
          2. _loadInstance
          3. _loadRows
          4. load
          5. loadCollection
          6. loadCollectionGraph
          7. Using Custom Loader Classes
        8. Validation
          1. addValidationRule
          2. getValidator
          3. isValidated
          4. removeValidationRules
          5. validate
      6. xPDOQuery
        1. xPDOQuery.andCondition
        2. xPDOQuery.groupby
        3. xPDOQuery.innerJoin
        4. xPDOQuery.leftJoin
        5. xPDOQuery.limit
        6. xPDOQuery.orCondition
        7. xPDOQuery.rightJoin
        8. xPDOQuery.select
        9. xPDOQuery.setClassAlias
        10. xPDOQuery.sortby
        11. xPDOQuery.where
      7. xPDORevisionControl
      8. xPDOTransport
        1. xPDOTransport.install
        2. xPDOTransport.pack
        3. xPDOTransport.uninstall
      9. xPDOValidator
        1. xPDOValidator.addMessage
        2. xPDOValidator.getMessages
        3. xPDOValidator.hasMessages
        4. xPDOValidator.validate

As PDO Wrapper

What is it?

PDO is the new standard data access layer for PHP, and it's capabilities are at the core of what xPDO is all about. An instance of PDO essentially represents a connection to a database, and by wrapping a PDO instance, essentially making it a "service" object, xPDO can provide a rich buffer between your object model and the persistence services responsible for handling all database communication.

And though it doesn't extend PDO directly, it does provide the same methods as PDO, which allows xPDO to mediate all database calls. This makes it possible to use result set caching and other advanced techniques to optimize how your applications interact with the database (i.e. by caching db results to file or memory, you can avoid even making the database connection if everything requested is found in the cache).

Finally, by simply extending xPDO yourself, you can further customize the class to serve the purposes you need it to. For instance, you can add domain-specific methods or extend core methods in your derivative and use instances as a central domain object for interacting with your model. This is how the MODx Revolution 2.0 Content Management System was built; the central class: modX, extends xPDO and adds the methods that form the MODx application domain.

You'll start off by extending the class like so:

class myClass extends xPDO

and then define a constructor method:

function __construct($options = array()) {
    $options = array(
        xPDO::OPT_CACHE_PATH => '/path/to/my/cache/dir',
        xPDO::OPT_TABLE_PREFIX => 'myprefix_',
        xPDO::OPT_HYDRATE_FIELDS => true,
        xPDO::OPT_HYDRATE_RELATED_OBJECTS => true,
        xPDO::OPT_HYDRATE_ADHOC_FIELDS => true,
        xPDO::OPT_VALIDATE_ON_SAVE => true,
    );
    parent :: __construct(
        'mysql:host=localhost;dbname=myxpdodb;charset=utf8',
        'username',
        'password',
        $options,
        array (
            PDO::ATTR_ERRMODE => PDO::ERRMODE_SILENT,
            PDO::ATTR_PERSISTENT => false,
            PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => true
        )
    );
    $this->setPackage('mypackage', 'path/to/my/model/');
}

There's a lot in there. You can find more information on the constructor here: The xPDO Constructor.

Suggest an edit to this page on GitHub (Requires GitHub account. Opens a new window/tab) or become an editor of the MODX Documentation.