2C. Loading and Querying Documents

CBMongoDB implements a chainable query syntax that those familiar to SQL querys will find convenient. It also simplifies the process dynamically generating search queries. Using our person entity, we created earlier, we can reset our entity and re-find it. The where() method accepts either where('name','value') arguments (which is equivalent to name=value) or where('name','operator','value'), which uses standard values like >, <, !=, etc. ¹:

person = person.reset().where('first_name','John').where('last_name','Doe').find();

Let's change our person's phone number:

person.setPhone_Home('616-555-8789');

The we can save the record, with our update() method:

person.update();

We can use our dot notation to find that record again - note the use of reset() to ensure our query criteria is empty

person = person.reset().where('phone.home','616-555-8789').find()

Now let's duplicate that document so we can play with multiple record sets

var newperson = structCopy(person.getDocument());

structDelete(newperson,'_id');

newperson = this.reset().populate(newperson).set('first_name','Jane').set('last_name','Doe').create();

Now we can find our multiple records - which will return an array (Note: We don't actually need to use reset() at this point, since saving an entity automatically evicts any criteria, but it's a good practice when starting a new query)

var people = this.reset().findAll();	

for(var peep in people){
	writeOutput("#peep.first_name# #peep.last_name# is in the house!");
}

Here's where we diverge from RDBMS: MongoDB uses a "cursor" on multiple record sets. It is extremely fast and, if you're going be looping through a large number of documents, is the way to go. Because of the way the cursor operates, it doesn't actually start executing queries on the database until the first time a record is requested. If we use the "asCursor" argument in findAll(boolean asCursor=false,boolean asJSON=false), we recevie the cursor back:

var people = this.reset().findAll(true);  //or findAll(asCursor=true), if you're feeling verbose	

while(people.hasNext()){
	var peep=people.next();
	writeOutput('#peep.first_name# #peep.last_name# is in the house!');
}

Lastly, let's clean up our test documents. The delete() function allows a boolean argument of "truncate" which defaults to FALSE. If you set this argument to true, without a loaded record or existing criteria, it will delete all documents from the collection. In this case, we're just going to delete our records one at a time, using our cursor:

var people = this.reset().findAll(true);

while(people.hasNext()){
	var peep=people.next();
	//notice how we're using bracket notation for our _id value. This is necessary because calling peep._id on the cursor object will throw an error  
	this.get(peep['_id']).delete();
}
	

Optionally, you could delete all records matching a given criteria using a where() clause:

var noDoes = this.reset().where('last_name','Doe').delete();

That's basic CRUD functionality. Read the API documentation for details on the individual functions and arguments.

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¹ Valid operators currently include "=","!=","<",">",">=","<=","IN" and "Exists"