CFMongoDB Object Mapper Syntax (proposed)

This is proposed syntax and subject to change. Unstable code can be found in the 0.9 branch.

There are 2 ways to create persistent objects in a MongoDB datastore using the CFMongoDB Object Mapper :
(1) Extending cfmongodb.components.MongoDocument, and
(2) Using the mongo.new_doc() factory method.

This provides 2 different approaches to generating the same types of objects. There are other ways, too [to do].

Method 1: Extending cfmongodb.components.MongoDocument

This is similar to CF9’s ORM syntax where you specify the fields you intend to persist as cfproperty tags. Though not required, this articulates what you intend to persist and initializes the model/data with default values (if any). The MongoDocument class has methods for storing and manipulating objects in the Mongo datastore – save(), update(), etc. [to do – link to API].

 <cfcomponent displayName="MyBlog" extends="cfmongodb.components.MongoDocument">
	<cfproperty name="title" />
	<cfproperty name="author" />
	<cfproperty name="pub_date" />
  	<cfproperty name="body" />
	<cfproperty name="comments" type="array" />
        <cfset super.init( collection_name='blog' ) />

    <cffunction name="validate">
     <!--- Insert custom code which will be executed prior to saves and updates --->
    </cffunction>

</cfcomponent>

To create a new MyBlog object and store it in Mongo, create the following client code:

<cfscript>
  my_blog = createObject( "component", "MyBlog" );
  my_blog.set( 'title', 'My New Blog Title' );
  my_blog.set( 'author', 'bill' );
  my_blog.set( 'pub_date', now() );
  my_blog.set( 'body', 'My brilliant ideas ...' );
  my_blog.save();
</cfscript>

Method 2: Using the new_doc() factory method

<cfscript>
  mongo= createObject( 'component', 'cfmongodb.components.MongoDb' );
  my_blog = mongo.new_doc( collection_name='blog' );
  my_blog.set( 'title', 'My New Blog Title' );
  my_blog.set( 'author', 'bill' );
  my_blog.set( 'pub_date', now() );
  my_blog.set( 'body', 'My brilliant ideas ...' );
  my_blog.save();
</cfscript>

The primary difference between the two methods is the way in which documents are created. But both methods perform identical tasks.

Fetching and Updating an Object (aka Document)

This has not been implemented and any suggestions are appreciated!

1. Create a instance of a MongoDocument
2. Retrieve an existing object using a known unique value; e.g. ObjectId ( _id )
3. Set the value of existing properties (or add new ones)
4. Call the update() method

In-place updates are not yet implemented, but are at the top of the list :-)

<cfscript>
  my_blog = createObject( 'component', 'cfmongodb.components.MongoDocument');
  my_blog = my_blog.fetch( '0x670Ac452B' );
  my_blog.set( 'body' , 'An even better idea ...');
  my_blog.update();
</cfscript>

Future versions will include in-place updates and should look something like:

<cfscript>
  my_blog = createObject( 'component', 'cfmongodb.components.MongoDocument');
  my_blog = my_blog.fetch( '0x670Ac452B' );
  my_blog.update( 'body', 'An even faster update!');
</cfscript>

Deleting an Object

Similar to updating, once a reference to a document object is retrieved, call the delete() method on the MongoDocument class:

<cfscript>
  my_blog = createObject( 'component', 'cfmongodb.components.MongoDocument');
  my_blog = my_blog.fetch( '0x670Ac452B' );
  my_blog.delete();
</cfscript>

Writing Large Binary Objects (BLOBS)

mongoDB supports storing BLOBS. It’s accomplished via the GridFS (Grid File System). Ideally, the API would hide the details of how this is implemented from developers, yet it will be available if needed. I’m not sure of the feasibility, yet, unlike all the other features.

<cfscript>
  avatar = fileRead( '/tmp/some_pic.png' ); //or via file upload ... any byte array, really
  mongo= createObject( 'component', 'cfmongodb.components.MongoDb' );
  my_blog = mongo.new_doc( collection_name='blog' );
  my_blog.set( 'title', 'My New Blog Title' );
  ...
  my_blog.set( 'avatar', avatar); 
  my_blog.save();
</cfscript>

Creating and Using Database References (DBRefs)

DBRefs can be used to store references to objects that exist in another collection. This is similar to a foreign key reference in relational terms.

Once a MongoDocument has been retrieved, call the dbref() method to generate a DBRef object. This object can then be stored as a property in another document:

<cfscript>
  mongo= createObject( 'component', 'cfmongodb.components.MongoDb' );
  my_blog = mongo.new_doc( collection_name='blog' );
  my_blog.set( 'title', 'My New Blog Title' );
  ... 
  my_blog.save();
  blog_ref = my_blog.dbref();

  my_site = mongo.new_doc( collection_name='sites' );
  my_site.set( 'blog', blog_ref );
  my_site.save();

 </cfscript>

The original object should be returned when performing a get():

<cfscript>
  blog = my_site.get( 'blog' );
  assertIsTypeOf( blog, 'cfmongodb.components.MongoDocument'  );
  writeoutput( blog.get( 'title' );
  ...
 </cfscript>

Comments Welcome!