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• CritConstants
• Criteria
• Impel
• Impel.CritConstants
• Impel.Criteria
• Impel.Criterion
• Impel.inTouch
• Impel.ResultSet
• ImpelClass
• ImpelPeer
• ResultSet
• String

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Class Impel

Impel is a Javascript to HTML 5 Object Relational Mapping Library

It is modeled after the PHP Propel library, but deviates from that API where necessary to support HTML5's asynchronous database interface.

Using Impel

Impel is a ....

Impel makes it easy to ...

Define the model

  var Card = new Class({
        Extends    : ImpelClass,
        peer_class : "CardPeer",
        toString   : function(){
                       return this.getName() + " of " + this.getSuit();
                     }
    });

  var CardPeer = new ImpelPeer({
         'columns'      : { 'id'    : 'card.id',    'suit' : 'card.suit', 
                                'value' : 'card.value', 'name' : 'card.name'},
         'table'        : 'card',
         'base_object'  : 'Card'
    });

 var Stack = new Class({
      Extends      : ImpelClass,
      peer_class   : "StackPeer",
      toString     : function(){
                       return this.getName();
                     }
    });

  var StackPeer = new ImpelPeer({
        'columns'      : { 'id'          : 'stack.id',         'name'       : 'stack.name', 
                           'created_at'  : 'stack.created_at', 'updated_at' : 'stack.updated_at'},
        'table'        : 'stack',
        'base_object'  :  'Stack'
    });

  var CardStack = new Class({
       Extends: ImpelClass,
       peer_class: "CardStackPeer",
       toString: function(){
         return this.getId() + ":" + this.getCardId() + "-" + this.getStackId();
       }
     });

  var CardStackPeer = new ImpelPeer({
          'columns'      : {'id' : 'card_stack.id', 'stack_id'  : 'card_stack.stack_id', 
                                                    'card_id'   : 'card_stack.card_id'},
          'table'        : 'card_stack',
          'base_object'  : 'CardStack'
     });

Define the relationships between the classes

    CardPeer.hasManyThrough("StackPeer::id","CardStackPeer::card_id","CardStackPeer::stack_id");
    StackPeer.hasManyThrough("CardPeer::id","CardStackPeer::stack_id","CardStackPeer::card_id");

Use the objects in your code

Instantiate the objects as you normally would and use the automatically created get and set methods to access the attributes of the objects.

 var cards  = [];

 cards[0]   = new Card();
   cards[0].setSuit("hearts");
   cards[0].setName("9");
   cards[0].setValue(9);

 cards[1]   = new Card();
   cards[1].setSuit("hearts");
   cards[1].setName("10");
   cards[1].setValue(10);

 cards[2]   = new Card();
   cards[2].setSuit("hearts");
   cards[2].setName("Jack");
   cards[2].setValue(11);

 cards[3]   = new Card();
   cards[3].setSuit("hearts");
   cards[3].setName("Queen");
   cards[3].setValue(12);

 cards[4]   = new Card();
   cards[4].setSuit("hearts");
   cards[4].setName("King");
   cards[4].setValue(13);

 var sFlush   = new Stack();
       sFlush.setName('Straight Flush');

Associate objects with one another

Objects that are related to one another through one-to-many and many-to-many relationships use automatically generated add and get methods rather than set and get methods

   sFlush.addCard(cards[0]);
   sFlush.addCard(cards[1]);
   sFlush.addCard(cards[2]);
   sFlush.addCard(cards[3]);
   sFlush.addCard(cards[4]);

Persist objects via the HTML 5 database

If objects are associated with one another you only need to call save on one of them. Impel will automatially save any related objects. Impel is also smart enough to figure out when an UPDATE is required instead of an INSERT. The HTML 5 specification requires that the HTML database be asynchronous, so Impel is as well. When you call save on an object nothing will be returned, but a callbacks will be used to signal if the save was successful or not. You can safely call save without a callback if you like.

 sFlush.save(
   function(){ 
     notify.show("Saved "+sFlush.getName() + " with " + sFlush.getCards().length + " cards.");
   },
   function(error){ 
     notify.error("Failed to save "+sFlush.getName() + " with " + 
                          sFlush.getCards().length + " cards." + error);
   }
 );

Retrieve objects from the HTML 5 database

To retrieve specific objects from the database first instantiate a Impel.Criteria object and use it to define exactly which object you want to retrieve. Then use that objects associated ImpelPeer to retrieve it.

 var c = new Impel.Criteria();
    c.add("StackPeer::name","Straight Flush");
 CardPeer.doSelectJoinAll(c, function(cards){ 
                                 cards.each(function(card){
                                     display(card);
                                 });
                             });

Class Summary

Constructor Attributes	Constructor Name and Description
	Impel(options, events) Impel is a Javascript to HTML 5 Object Relational Mapping Library It is modeled after the PHP Propel library, but deviates from that API where necessary to support HTML5's asynchronous database interface.

Field Summary

Field Attributes	Field Name and Description
<static>	Impel.db The HTML 5 SQL database to execute queries against
<static>	Impel.JsonP Add in our own JsonP class because the standard clientcide version does not inform us of failures and does not support a predefined name for the callback function.

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