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>>http://squeryl.org/]] 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>>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).
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 ##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		-*
34		-** Entity.eotemplate [[template>>WOL:Squeryl _Entity.eotemplate]]
35		-** 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}}
	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