lib/main.js
function(label, property_key, callback) {
	var that = this;
	var val = new Validator();
	val.label(label).property(property_key);

	if (val.hasErrors) {
		return callback(val.error(), null);
	}

	request
		.post(that.url + '/db/data/schema/constraint/' + label + '/uniqueness')
		.set(this.header)
		.send({ 'property_keys' : [property_key] })
		.end(function(result) {
			switch(result.statusCode) {
				case 200:
					callback(null, result.body);
					break;
				case 409:
					callback(null, false); // Constraint already exists
					break;
				default:
					callback(new Error('HTTP Error ' + result.statusCode + ' when creating a uniqueness contraint.'), null);
			}
		});
}
function(label, property_key, callback) {
	var that = this;
	var val = new Validator();
	val.label(label).property(property_key);

	if (val.hasErrors) {
		return callback(val.error(), null);
	}

	request
		.post(that.url + '/db/data/schema/constraint/' + label + '/uniqueness')
		.set(this.header)
		.send({ 'property_keys' : [property_key] })
		.end(function(result) {
			switch(result.statusCode) {
				case 200:
					callback(null, result.body);
					break;
				case 409:
					callback(null, false); // Constraint already exists
					break;
				default:
					callback(new Error('HTTP Error ' + result.statusCode + ' when creating a uniqueness contraint.'), null);
			}
		});
}
/* CONSTRAINTS /*	Create a uniqueness constraint on a property.
Example:
createUniquenessConstraint('User','email', callback);
returns 	{
'label' : 'User',
'type' : 'UNIQUENESS',
'property-keys' : [ 'email' ]
}