! Miscellanous

In this section we present some questions that occured on the Pharo mailing-list and may help you.

!! Mongo collection 
One question is if it Is  possible to retrieve data from Mongo collection if it was not created via Voyage.
The answer is yes but you need to customize a bit.

# Make sure you refer to the right collection.
[[[
descriptionContainer
	<mongoContainer>
	^ VOMongoContainer new
		collectionName: 'yo'
		yourself
]]]
#  For materializationyou should at least have some fields such ==\_id==.

You can ask the serializer for the fields:
[[[
VOMongoSerializer fieldVersion (#version)
VOMongoSerializer fieldType (#instanceOf)
]]]

You can probably add ==#version== and ==#instanceOf== to your existing objects.



the solution to my initial issue is to create a class MyClass with two class side methods

MyClass class >> isVoyageRoot
	^ true

MyClass class >> descriptionContainer
    <voyageContainer>
    ^ VOContainer new
        collectionName: 'myCollection';
        yourself

Also, to properly read the data one should add instance variables to depending on what is in the database. For example:

{ "_id" : ObjectId("5900a0175bc65a2b7973b48a"), "item" : "canvas", "qty" : 100, "tags" : [ "cotton" ] }

In this case MyClass should have instanceVariables: 'item qty tags' and accessors.
Plus, on the class side

mongoItem
	<mongoDescription>
	^ VOToOneDescription new
		attributeName: 'item';
		kind: String;
		yourself

mongoQty
	<mongoDescription>
	^ VOToOneDescription new
		attributeName: 'qty';
		kind: Integer;
		yourself

mongoTags
	<mongoDescription>
	^ VOToOneDescription new
		attributeName: 'tags';
		kind: OrderedCollection;
		yourself

After that one can connect to database and get the information.

| repository | 
repository := VOMongoRepository database: 'databaseName'.
repository selectAll: MyClass

Big thanks to Sabine, Esteban and Holger!