Changes for page WebObjects and Squeryl

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1		-= Squeryl ~= //SQL-like// DSL in Scala =
	1	+= Squeryl ~= //SQL-like// DSL for Scala =
2	2
3		-Advantages of [[Squeryl>>url:http://squeryl.org/||shape="rect"]] over EOF:
	3	+Advantages of Squeryl 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		-** 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
15		-
16		-= Migrating EOF -> Squeryl =
17		-
18		-In contrast to EOF Squeryl maintains its ORM information programmatically - in the classes itself and collectively in a [[schema>>url:http://squeryl.org/schema-definition.html||shape="rect"]]. In keeping with the strongly-typed philosophy of Scala, Squeryl has no dynamic component like EOF (i.e an EO model file).
19		-
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.
21		-
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 {{code language="none"}}EOGenericRecord{{/code}}.
25		-* Mark the abstract many-To-Many join entities as {{code language="none"}}Abstract{{/code}}.
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 {{code language="none"}}File Names{{/code}} extension to "scala".
31		-1. Use the Squeryl EO Templates:
32		-1*. _Entity.eotemplate [[template>>doc:WOL.Squeryl _Entity\.eotemplate]]
33		-1*. Entity.eotemplate [[template>>doc:WOL.Squeryl Entity\.eotemplate]]
34		-
35		-{{note title="Note"}}
36		-Any custom business "logic" will have to be manually re-written in Scala
37		-{{/note}}
38		-
39		-== Differences Between a Squeryl Schema and EO Model/Classes ==
40		-
41		-* Optional attributes (i.e those that {{code language="none"}}allowsNull{{/code}}) are typed as {{code language="none"}}Option[WO:T]{{/code}}
42		-* To one relationships that are not mandatory (i.e optional relationships) are also typed as {{code language="none"}}Option[WO:T]{{/code}}
43		-* To many relationships are represented as a Squeryl iterable (collection class) as opposed to a {{code language="none"}}NSArray{{/code}}.
44		-
45		-=== Use of Scala Collections ===
46		-
47		-===== 1. Filtering =====
48		-
49		-Instead of using EOQualifiers to filter EOs dynamically, you can apply the type safe filter in Scala:
50		-
51		-{{code}}
52		-
53		-def activeFiles = files.filter(_.active == true)
54		-
55		-{{/code}}
56		-
57		-===== 2. Iteration =====
58		-
59		-Functional language iteration that's become increasingly popular can be used:
60		-
61		-{{code}}
62		-
63		-activeFiles.foreach(f => {
64		- ...
65		-})
66		-
67		-{{/code}}
68		-
69		-===== 3. For-Comprehensions =====
70		-
71		-Here's just an example use of sequence comprehension:
72		-
73		-{{code}}
74		-
75		-def activeFiles = for (file <- files if file.active == true) yield file
76		-
77		-{{/code}}
	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