Changes for page WebObjects and Squeryl

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1		-= Squeryl ~= //SQL-like// DSL for Scala =
	1	+= Squeryl ~= //SQL-like// DSL in Scala =
2	2
3		-Advantages of Squeryl over EOF:
	3	+Advantages of [[Squeryl>>http://squeryl.org/]] over EOF:
4	4
5	5	* Concurrent
6	6	** Spawns multiple database connections
7	7	** Issues database transactions concurrently
8	8	* Scala Actor compatible
9		-* Immutable object model/graph
10		-* Strongly-typed
11		-** Better suited for business "logic".
12		- E.g: Exploiting the compiler and IDE to catch exceptions at compile time rather than at run-time.
13		-* Uses Scala (functional) collection classes
	9	+** Immutable object model/graph
	10	+** Explicit transaction control
	11	+* Type Safety
	12	+** Better suited for database/business "logic".
	13	+ E.g: Exploits the compiler and IDE to catch exceptions at compile time rather than at run-time.
	14	+* Uses Scala Collections
14	14
15	15	= Migrating EOF -> Squeryl =
16	16
17		-In keeping with the strong-typed philosophy of Scala, Squeryl has no dynamic component like EOF (i.e an EO model file).
	18	+In contrast to EOF Squeryl maintains its ORM information programmatically - in the classes itself and collectively in a [[schema>>http://squeryl.org/schema-definition.html]]. In keeping with the strongly-typed philosophy of Scala, Squeryl has no dynamic component like EOF (i.e an EO model file).
18	18
19		-EOF though has the ability to generate classes in Java (and in Objective-C prior to WebObjects 4.5) enforcing type as has become customary in enterprise environments. We may exploit this feature of EOF to generate a Squeryl schema.
	20	+EOF has the ability to generate classes in Java (and in Objective-C prior to WebObjects 4.5) because enforcing type has become customary in enterprise environments. We may exploit this feature of EOF to generate a Squeryl schema from an EO model.
20	20
21		-* Squeryl Templates
	22	+=== Preparing your EO model ===
	23	+
	24	+* Make sure **all** EO entities have a class name (including abstract many-To-many "join" tables). FYI: There can be no support for entities classified as ##EOGenericRecord##.
	25	+* Mark the abstract many-To-Many join entities as ##Abstract##.
	26	+* (Temporary) Ensure all the model entities are in the same package. i.e the package is exclusive to the model.
	27	+
	28	+=== Generating the Squeryl Schema ===
	29	+
	30	+1. Create a .eogen file for your EO model as normal. Only set the ##File Names## extension to "scala".
	31	+1. Use the Squeryl EO Templates:
	32	+
	33	+*
22	22	** Entity.eotemplate [[template>>WOL:Squeryl _Entity.eotemplate]]
23	23	** Entity.eotemplate [[template>>WOL:Squeryl Entity.eotemplate]]
	36	+
	37	+{{note title="Note"}}
	38	+
	39	+Any custom business "logic" will have to be manually re-written in Scala
	40	+
	41	+{{/note}}
	42	+
	43	+== Differences Between a Squeryl Schema and EO Model/Classes ==
	44	+
	45	+* Optional attributes (i.e those that ##allowsNull##) are typed as ##OptionWO:T##
	46	+* To one relationships that are not mandatory (i.e optional relationships) are also typed as ##OptionWO:T##
	47	+* To many relationships are represented as a Squeryl iterable (collection class) as opposed to a ##NSArray##.
	48	+
	49	+=== Use of Scala Collections ===
	50	+
	51	+===== 1. Filtering =====
	52	+
	53	+Instead of using EOQualifiers to filter EOs dynamically, you can apply the type safe filter in Scala:
	54	+
	55	+{{code}}
	56	+
	57	+def activeFiles = files.filter(_.active == true)
	58	+
	59	+{{/code}}
	60	+
	61	+===== 2. Iteration =====
	62	+
	63	+Functional language iteration that's become increasingly popular can be used:
	64	+
	65	+{{code}}
	66	+
	67	+activeFiles.foreach(f => {
	68	+ ...
	69	+})
	70	+
	71	+{{/code}}
	72	+
	73	+===== 3. For-Comprehensions =====
	74	+
	75	+Here's just an example use of sequence comprehension:
	76	+
	77	+{{code}}
	78	+
	79	+def activeFiles = for (file <- files if file.active == true) yield file
	80	+
	81	+{{/code}}