Tutorial

[Sebastian Sastre]

Hey Robert,
 
    Is not Magma directly related case. I think that is from the package
with addons for Seaside that Keith Hodges made. I'm sure you can ask him on
the Seaside list,
 
    cheers,
 
Sebastian Sastre




  _____  

De: magma-bounces at lists.squeakfoundation.org
[mailto:magma-bounces at lists.squeakfoundation.org] En nombre de Robert
Schwarz
Enviado el: Lunes, 19 de Noviembre de 2007 19:15
Para: magma at lists.squeakfoundation.org
Asunto: Tutorial


Error: Magma helper not selected in application configuration.
When I add the WAMagmaConfiguration I see the Magma configuration group but
I didn't found any drop down menu where I can select WAMagma. 

How can I configure my application for the Magma helper?

Robert

Am 28.10.2007 um 06:57 schrieb Keith Hodges:


There have been calls for a Magma tutorial to go into the Seaside tutorial
in the persistency chapter. This chapter already includes Glorp and GOODS.

Just in case someone is already, or thinking of doing this, I have already
written such a mini tutorial.

In order to make Magma even easier to use, I have begun rewriting "Magma
seaside" to take advantage of my new Seaside Session Helpers interface,
which I released yesterday.

The idea being that you can now use Magma, without a specialized Seaside
Session class. This should make it easier for users to adopt Magma for their
existing applications.

I am a little unsure as to how you are supposed to obtain an exact match of
a unique item from the database. 
This is how I would do it (althought I know MagmaCollections dont actually
implement #firstOrNil)

^ (self users where: [ :each | each email = anEmail ]) firstOrNil

Is there a better way to obtain a unique value?

cheers

Keith

p.s. the wiki page that I refer to on MagmaCollections is a bit out of date.
----

so far... 

Saving all data in an object-oriented database: Magma

Another option to make your data persistent is to use an object-oriented
database like Magma.

Installing the Magma Database

Magma is written entirely in Squeak, so there is no need to install a
separate server application. Both Magma and Seaside can run in the same
image. To install (into a 3.10 based image) just execute the following.
(This may take a while)

Installer universes install: 'Magma seasideHelper'.

Configuring your application to use Magma

In the configuration for the 'todo' application you will need to add
WAMagmaConfiguration to the configuration "ancestry". Select it from the
drop down menu and click "Add". As soon as you do this, a new group of
configuration options will appear. You will need to select the "WAMagma",
helper class from the drop down menu.

The WAMagma class provides the basic interface between Magma Sessions and
Seaside Sessions. Subclasses provide specialised session management such as
shared or pooled sessions. 

Using Magma

Magma is very easy to use with seaside. To obtain and use a database session
helper, simply send #magma to the current session. For example the code
"self session magma" will work within all seaside components.

To use Magma in this application in a similar manner to the way we have
connected to databases in other examples we need to create an interfacing
class, to which we can add our specialized querying methods.

Dictionary subclass: #StMagmaDatabase
    instanceVariableNames: ''
    classVariableNames: ''
    poolDictionaries: ''
    category: 'STTutTodoApp'

StSession-#initialize
    super initialize.
    self db: (self magma rootAs: StMagmaDatabase)

The tutorial application accesses the database via the #db accessor. Here we
define this using the #rootAs: helper method, which does everything we need,
both to initialize the database, and to provide us the interface that we
want to it.

To initialize our users collection we define the initialization on our root
object, and we need a method to return the users from the database, to add a
new user, and to find a user.

StMagmaDatabase-#initialize
    | users |
    users := OrderedCollection new.
    self at: #users put: users.

StMagmaDatabase-#users
        ^ self at: #users  

StMagmaDatabase-#addUser: newUser
        ^ self users add: newUser

StMagmaDatabase-#findUserByEmail: anEmail
    ^ self users 
        detect: [:each | each email = anEmail] 
        ifNone:[]

Notice how for basic usage we have not needed any database specific code! If
our userbase is going to grow to a significant size it makes sense to re
implement the above using some database features, so we introduce a
MagmaCollection which you can read about in detail here:
http://wiki.squeak.org/squeak/2639

initialize
    | users |
    users := MagmaCollection new.
    users addIndex: (MaSearchStringIndex attribute: #userName) beAscii.
    users addIndex: (MaSearchStringIndex attribute: #email) beAscii.
    self at: #users put: users

StMagmaDatabase-#users
        ^ self at: #users  

StMagmaDatabase-#addUser: newUser
        ^ self users add: newUser

StMagmaDatabase-#findUserByEmail: anEmail
    ^ (self users where: [ :each | each email = anEmail ]) firstOrNil

... need to explain how committing works... etc




 

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