The document discusses tools and techniques for developing Grails applications. It describes using Grails, IntelliJ IDEA, MySQL, JUnit and other tools for specification, design, construction, testing and deployment. It also discusses implementing common domain classes with status enumerations and default filters to control data visibility based on status in the backend vs frontend.

1. Grails
Code
from
the
Trenches
Collec3ons.shuffle(dayToDayWork)

2. Edwin
van
Nes
1989
dBase
/
Clipper
/
FoxPro
1995
Borland
Delphi
2000
Java
2,
Enterprise
Edi3on
2005
PHP,
Typo3,
Joomla!,
…
2011
Groovy
&
Grails

3. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API

4. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
PlantUML,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
Kiln,
…
Deployment
Jenkins,
Gradle,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

5. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
Kiln,
…
Deployment
Jenkins,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

6. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
…
Deployment
Jenkins,
Gradle,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

7. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
Kiln,
…
Deployment
Jenkins,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

8. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
…
Deployment
Jenkins,
Gradle,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

9. Weapons
of
Choice
Specifica3on
Google
Docs,
FogBugz,
Balsamiq
Mockups,
yEd,
…
Design
similar
stuff
Construc3on
Grails
(dûh!),
IntelliJ
IDEA,
mySQL,
SVN
-­‐>
GIT,
…
Tes3ng
JUnit,
Spock,
…
Deployment
Jenkins,
OSX,
Ubuntu,
MS
Windows,
…
Project
Skype,
Google
Hangout,
IRIS,
…

10. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API
• Error
Abstrac3on
in
a
Plugin

11. WhatWeDoMost*
Services
Frontend
Portal
Backend
Portal
Database
Our
Clients
Consumers
(their
clients)
*
overly
simplified
for
educa3onal
purposes

12. GR8Tunes
Used
here
as
an
example
for
a
typical
Backend
portal

13. GR8Tunes
Used
here
as
an
example
for
a
typical
Backend
portal

14. AbstractDomain
• Not
too
Groovy
probably
• Add
some
standard
akributes
– Some
useful
3mestamps
– ‘recentlyUpdated’
boolean
for
easy
highligh3ng
– Each
record
gets
a
‘remarks’
akribute

15. AbstractDomain.Status

16. AbstractDomain.Status
Hibernate
filters
Plugin
• defaultFilter
in
Backend
– Status
in
[Status.ACTIVE,
Status.INACTIVE]
• defaultFilter
in
Frontend
– Status
==
Status.ACTIVE

17. AbstractDomain.Status
Hibernate
filters
• defaultFilter
in
Backend
– Status
in
[Status.ACTIVE,
Status.INACTIVE]
• defaultFilter
in
Frontend
– Status
==
Status.ACTIVE

18. AbstractDomain.Status
class
DefaultFilters
{
def
sessionFactory
def
filters
=
{
all(controller:'*',
action:'*')
{
before
=
{
def
session
=
sessionFactory.currentSession
if
(params.filter_status)
{
session.enableFilter('statusFilter').setParameter('status',params.filter_status)
}
else
{
session.enableFilter('defaultFilter')
}
}
}
}
}

19. AbstractDomain.Status
class
DefaultFilters
{
def
sessionFactory
def
filters
=
{
all(controller:'*',
action:'*')
{
before
=
{
def
session
=
sessionFactory.currentSession
if
(params.filter_status)
{
session.enableFilter('statusFilter').setParameter('status',params.filter_status)
}
else
{
session.enableFilter('defaultFilter')
}
}
}
}
}

20. AbstractDomain.Status
class
DefaultFilters
{
def
sessionFactory
def
filters
=
{
all(controller:'*',
action:'*')
{
before
=
{
def
session
=
sessionFactory.currentSession
if
(params.filter_status)
{
session.enableFilter('statusFilter').setParameter('status',params.filter_status)
}
else
{
session.enableFilter('defaultFilter')
}
}
}
}
}

21. AbstractDomain.change
• Holds
a
record
of
type
AbstractDomain
• Like
a
“muta3on-­‐record”
• i.e.
future
change
to
the
object
• example:
division
of
responsibility
(amongst
users)

22. AbstractDomain.change
id
version
change
.tle
year
1
5
7
The
Bright
Side
of
the
Moon
1973
id
version
change
.tle
year
7
5
null
The
Dark
Side
of
the
Moon
1973
Should
verify
(op3mis3c)
Hibernate
filter:
exclude
records
that
are
“change
records”

23. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API
• Error
Abstrac3on
in
a
Plugin

24. Heavy-­‐Duty
Scaffolding
• Substan3al
3me
spent
on
tailor-­‐made
scaffolding
• Controllers
are
always
scaffolded
– Only
specific
code
for
a
specific
domain
is
coded
• Views
are
scaffolded
as
a
start
– Much
more
likely
to
manually
adjust
– But
certainly
not
for
each
and
every
Domain
Class
• Domain
Classes
can
contain
seungs
to
influence
rendering
during
scaffolding

25. Scaffolded
Controllers
• All
Controllers
exists
as
files
but
are
100%
scaffolded
unless
…
class
AlbumController
{
static
scaffold
=
true
}

26. Scaffolded
Controllers
• All
Controllers
exists
as
files
but
are
100%
scaffolded
unless
…
class
AlbumController
{
static
scaffold
=
true
def
list
(Integer
max)
{
//
different
implementation
of
Album.list
}
}

27. SimpleFlow
=
true
• Simple
states
– List
– Edit
• Mul3ple
ac3ons
– Create
– Cancel
– Save
– SaveAndClose
– SaveAndCreate

28. SimpleFlow
=
false
• More
states
– List
– Create
– Edit
– Show
• Same
set
of
ac3ons
– Create
– Cancel
– Save
– SaveAndClose
– SaveAndCreate

29. Scaffolded
Views
• Views
are
most
likely
to
be
changed
– Order
of
fields
from
Domain
Class
constraints
static
constraints
=
{
title
(blank:false)
artist
(blank:false)
year
(display:true)
change
(display:false)
}

30. Scaffolded
Views
• Views
are
most
likely
to
be
changed
– Order
of
fields
from
Domain
Class
constraints
static
constraints
=
{
title
(blank:false)
artist
(blank:false)
year
(display:true)
change
(display:false)
}

31. Scaffolded
Views
• Render
more
artefacts
_form.gsp
=
fields
used
in
create
/
edit
_table.gsp
=
<table>
used
in
list
for
reuse
_panel.gsp
=
simple
<div>
for
reuse
list.csv.gsp
=
used
for
formatting
exports

32. Scaffolded
Views
• Render
more
artefacts
_form.gsp
=
fields
used
in
create
/
edit
_table.gsp
=
<table>
used
in
list
for
reuse
_panel.gsp
=
simple
<div>
for
reuse
list.csv.gsp
=
used
for
formatting
exports
<%@
page
import="gr8tunes.Album"
%>
<g:if
test="${albumInstance
instanceof
Album}">
<div
class="domain-­‐panel
domain-­‐album">
<h4><small><g:message
code="album.title.label"
/>:</small></h4>
<p>
<g:if
test="${!controllerName.equals('album')}">
<g:link
controller=”album"
action="show"
id="${albumInstance.id}">
<g:fieldValue
bean="${albumInstance}"
field="year"/>
<g:fieldValue
bean="${albumInstance}"
field="title"/>
</g:link>
</g:if>
<g:else>
<g:fieldValue
bean="${albumInstance}"
field="year"/>
<g:fieldValue
bean="${albumInstance}"
field="title"/>
</g:else>
</p>
</div>
</g:if>
_panel.gsp

33. Scaffolded
Views
• Render
more
artefacts
_form.gsp
=
fields
used
in
create
/
edit
_table.gsp
=
<table>
used
in
list
for
reuse
_panel.gsp
=
simple
<div>
for
reuse
list.csv.gsp
=
used
for
formatting
exports

34. Scaffolded
Views
• Render
more
artefacts
_form.gsp
=
fields
used
in
create
/
edit
_table.gsp
=
<table>
used
in
list
for
reuse
_panel.gsp
=
simple
<div>
for
reuse
list.csv.gsp
=
used
for
formatting
exports

35. Scaffolded
Views
• Render
more
artefacts
_form.gsp
=
fields
used
in
create
/
edit
_table.gsp
=
<table>
used
in
list
for
reuse
_panel.gsp
=
simple
<div>
for
reuse
list.csv.gsp
=
used
for
formatting
exports

36. Scaffolding
seungs
in
Domain
Classes
class
Item
extends
AbstractDomain
{
...
static
scaffolding
=
[
simpleFlow:
true,
inFilter:
['status',
'itemType',
'itemCategory'],
inSearch:
['title',
'description'],
inSort:
['title',
'itemType',
'artist']
]
...
}

37. Scaffolding
seungs
in
Domain
Classes
class
Item
extends
AbstractDomain
{
...
static
scaffolding
=
[
simpleFlow:
true,
inFilter:
['status',
'itemType',
'itemCategory'],
inSearch:
['title',
'description'],
inSort:
['title',
'itemType',
'artist']
]
...
}

38. Scaffolding
seungs
in
Domain
Classes
class
Item
extends
AbstractDomain
{
...
static
scaffolding
=
[
simpleFlow:
true,
inFilter:
['status',
'itemType',
'itemCategory'],
inSearch:
['title',
'description'],
inSort:
['title',
'itemType',
'artist']
]
...
}

39. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API
• Error
Abstrac3on
in
a
Plugin

40. Mul3-­‐lingualiza3on
• Transla3on
of
program
code
– aka
i18n;
that’s
in
Grails
right?
– .proper3es
file
per
‘group
of
(Domain)
classes’
• album.proper3es
• messages.proper3es
• abstractDomain.proper3es
• enums.proper3es
• Transla3on
of
data
(records)
– That’s
what
we
refer
to
as
“m17n”

41. Mul3-­‐lingualiza3on
• Transla3on
of
program
code
– aka
i18n;
that’s
in
Grails
– .proper3es
file
per
“group
of
Domain
classes”
• album.proper3es
• messages.proper3es
• abstractDomain.proper3es
• enums.proper3es
• Transla3on
of
objects
(records)
– That’s
what
we
refer
to
as
“m17n”

42. Mul3-­‐lingualiza3on
• System
default
Language
reflects
the
language
of
all
record
in
the
database
• Data
is
op3onally
“overlayed”
with
an
M17n
record
• By
conven3on
– i.e.
if
the
domain-­‐name
ends
in
“M17n”
– Scaffolding
renders
a
different
controller
– Scaffolding
renders
a
different
view

43. AbstractDomain.change
id
.tle
year
image
ar.st_id
descrip.on
3
Licensed
to
Ill
1986
/img/4529ad62}.png
5
The
first
rap
rock
LP
to
top
the
Billboard
album
chart
id
album_id
language_id
.tle
descrip.on
1
3
7
Licensed
to
Ill
Es
ist
das
erste
reine
Hip-­‐Hop-­‐Album,
das
Platz
1
in
den
US-­‐amerikanischen
Billboard-­‐Charts
erreichte.
2
3
4
Licensed
to
Ill
La
canzone
raggiunse
la
seuma
posizione
nella
speciale
classifica
del
”Billboard
Hot
100"
Album
AlbumM17n
Language.isSystem
==
false
Rela3ons
are
not
overlay
/
translated
(could
be
a
limita3on)
Not
overlayed
Not
overlayed

44. m17n
service
Class
Album
extends
AbstractDomain
{
def
m17nService
private
String
title
...
public
String
getTitle()
{
m17nService.getProperty(this,
‘title’)
}
}

45. m17n
service
Class
Album
extends
AbstractDomain
{
def
m17nService
private
String
title
...
public
String
getTitle()
{
m17nService.getProperty(this,
‘title’)
}
}
The
m17nService
can
figure
out:
• If
an
overlay
Class
exists
(by
conven3on)
• What
the
system
language
is
…
Language.findByIsSystem(true)
• What
the
requested
Language
is
(from
Session)
• …
or
return
the
un-­‐translated
…
this[title]
NB.
Session
does
not
necessarily
contain
browser
locale,
users
can
override
this

46. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API

47. Types
&
Categories
• Types
– Hardcoded
– Used
by
program-­‐code(business-­‐logic,
rendering
etc.)
• Categories
– Added
wherever
they
could
be
somewhat
useful
to
a
par3cular
user
– Used
in
the
UI
for
quick
filters
– Used
in
the
UI
for
color-­‐coding

48. Types
&
Categories
• Types
– Hardcoded
– Use
by
program-­‐code
(business-­‐logic,
rendering
etc.)
• Categories
– Added
wherever
they
could
be
somewhat
useful
to
a
par3cular
user
– Used
in
the
UI
for
quick
filters
– Used
in
the
UI
for
color-­‐coding

49. Types
&
Categories
• Types
– Hardcoded
– Use
by
program-­‐code
(business-­‐logic,
rendering
etc.)
• Categories
– Added
wherever
they
could
be
somewhat
useful
to
a
par3cular
user
– Used
in
the
UI
for
quick
filters
– Used
in
the
UI
for
color-­‐coding

50. An
overview
…
just
for
the
fun
of
it

51. Direc3ons
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API

52. Now
something
completely
different

53. Connector
for
API
-­‐>
Grails
• Example
of
calling
the
Flickr
REST
API
• Explain
my
approach
to
API
wrapping

54. Abstrac3on
of
an
API
call
1. Validate
the
parameters
needed
for
the
par3cular
call
2. Well
eh,
do
the
actual
API
call
3. Process
the
response
or
handle
any
errors

55. Abstrac3on
of
an
API
call
1. Validate
the
parameters
needed
for
the
par3cular
call
2. Well
eh,
do
the
actual
API
call
3. Process
the
response
or
handle
any
errors
void
apiCall(method,
params)
{
if
(validator(params))
{
try
{
def
rsp
=
doApiCall(method,params)
return
process(rsp)
}
catch
(Exception
ex)
{
...
}
}
else
{
//
todo:
raise
validation
exception
}
}
Params
Validator
Processor
API

56. Abstrac3on
of
an
API
call
//
abstracting
the
whole
call
handling
with
closures
implemented
in
individual
classes
private
def
apiCall(FlickrApiMethod
apiImplementation,
def
apiModel
=
{}
)
{
def
params
=
apiImplementation.paramsClosure
def
validator
=
apiImplementation.validatorClosure
def
processor
=
apiImplementation.processorClosure
if
(validator(apiModel()))
{
try
{
def
rsp
=
doApiCall(apiImplementation.apiMethod,
params(apiModel()))
return
processor(rsp,apiModel())
}
catch
(FlickrException
ex)
{
FlickrExceptionHandler.handleApiCallException(ex)
}
}
//
TODO:
raise
validation
exception
return
apiModel()
}

57. Implementa3on
class
photosGetInfo
implements
FlickrApiMethod{
//
API
METHOD
static
final
String
apiMethod
=
'flickr.photos.getInfo'
//
VALIDATOR
Closure
validatorClosure
=
{
FlickrPhoto
photo
-­‐>
if
(!photo
||
!photo?.id)
{
return
[validated:false,
message:"Required
value
FlickrPhoto.id
missing”]
}
return
[validated:true]
}
//
PARAMS
Closure
paramsClosure
=
{
FlickrPhoto
photo
-­‐>
[photo_id:photo?.id,
secret:(photo?.secret
?:'')]
}
...

58. Implementa3on
class
photosGetInfo
implements
FlickrApiMethod{
...
//
PROCESSOR
Closure
processorClosure
=
{
GPathResult
response,
FlickrPhoto
photo
-­‐>
photo.isPublic
=
(response.photo.visibility.@ispublic?.toString()
==
'1')
photo.secret
=
response.photo.@secret.toString()
photo.serverId
=
response.photo.@server.toInteger()
photo.title
=
response.photo.title.toString()
...
return
photo
}
...

59. Implementa3on
class
photosGetInfo
implements
FlickrApiMethod{
...
//
ERROR
CODES
Closure
errorsClosure
=
{
GPathResult
response
-­‐>
if
(response.err.@code.toInteger()
==
1)
{
return
null
}
//
photo
not
found
//
recoverable
errors
if
([100,105,116].contains(response.err.@code.toInteger()))
{
return
new
FlickrServiceApiException(response)
}
else
{
return
new
FlickrServiceSyntaxException(response)
}
}
}

60. We
we’re
at
• We’ve
got
a
generic
implementa3on
of
calls
• A
Class
that
implements
a
par3cular
call
• The
params
back-­‐and-­‐forth
are
Groovy
• Now
3e
it
all
together
in
a
Grails-­‐like
way

61. Service.getPhotoById(..)
class
flickrService
{
…
//
abstracting
call
handling
implemented
in
individual
classes
private
def
apiCall(def
apiImplementation,
def
apiModel
=
{})
{
…
}
//
public
service
methods
public
FlickrPhoto
getPhotoById(Long
id)
{
return
apiCall(
new
photosGetInfo(),
{new
FlickrPhoto(id:id)}
)
as
FlickrPhoto
}

62. Well,
that’s
a
Wrap
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API

63. Well,
that’s
a
Wrap
• Weapons
of
Choice
• AbstractDomain
• Heavy-­‐Duty
Scaffolding
• Mul3-­‐lingualiza3on
• Types
&
Categories
• Connec3ng
an
API

64.
edwin@ihomer.nl
linkedin.com/in/edwinvannes
twiker.com/edwinvannes