Many to many mapping

> Hello.
>
> I am trying to map a many-to-many relationship in glorp.
>
> I have a class named 'User' and a class named 'Group'. These class have two
> relationships, the first one is one-to-may and expresses the 'owner'
> feature, and the other is many-to-many and expresses which user belong to
> which group, in other words, an user belongs to many groups and a groups
> contains many users.
>
> My problem is when I try to map the many-to-many relationship, reading some
> tutorials I figure out that I need to specify the association table, but I
> tried many ways to do that without success...
>
> The code generate the database successfully, also the one-to-many
> relationship, but when I try to add a member to a group, does not throw any
> exception, only a log error in Posgres Admin "Se encontro fin de archivo
> inesperado en la conexion del cliente", something like it found an
> unexpected end of file was found in the client connection.
>
> Sorry for the bad english.
>
> My code is the following.
>
> classModelForGroup: aClassModel
>
> aClassModel newAttributeNamed: #id.
> aClassModel newAttributeNamed: #name
>
> classModelForUser: aClassModel
>
> aClassModel newAttributeNamed: #id.
> aClassModel newAttributeNamed: #username.
> aClassModel newAttributeNamed: #password.
> aClassModel newAttributeNamed: #tweets collectionOf: TwittAR.Tweet.
> aClassModel newAttributeNamed: #groups collectionOf: TwittAR.Group.
> aClassModel newAttributeNamed: #groupsIbelong collectionOf: TwittAR.Group
>
> descriptorForGroup: aDescriptor
>
> | table linkTable |
> self tableNamed: 'GROUP_HAS_USER'.
> linkTable := self tableNamed: 'GROUP_HAS_USER'.
> table := self tableNamed: 'GROUPS'.
> aDescriptor table: table.
> (aDescriptor newMapping: Glorp.DirectMapping) from: #id to: (table
> fieldNamed: 'id').
> (aDescriptor newMapping: Glorp.DirectMapping) from: #name to: (table
> fieldNamed: 'name').
> (aDescriptor newMapping: Glorp.ManyToManyMapping)
> attributeName: #members;
> referenceClass: TwittAR.User;
> mappingCriteria: (Glorp.Join
>     from: (table fieldNamed: 'id')
>     to: (linkTable fieldNamed: 'group_id')).
> (aDescriptor newMapping: Glorp.ManyToManyMapping)
> attributeName: #tweets;
> referenceClass: TwittAR.Tweet
>
> descriptorForUser: aDescriptor
>
> | table linkTable |
> table := self tableNamed: 'USERS'.
> linkTable:= self tableNamed: 'GROUP_HAS_USER'.
> aDescriptor table: table.
> (aDescriptor newMapping: Glorp.DirectMapping) from: #id to: (table
> fieldNamed: 'id').
> (aDescriptor newMapping: Glorp.DirectMapping) from: #username to: (table
> fieldNamed: 'username').
> (aDescriptor newMapping: Glorp.DirectMapping) from: #password to: (table
> fieldNamed: 'password').
> (aDescriptor newMapping: Glorp.OneToManyMapping) attributeName: #tweets.
> (aDescriptor newMapping: Glorp.OneToManyMapping) attributeName: #groups.
>
> (aDescriptor newMapping: Glorp.ManyToManyMapping)
> attributeName: #groupsIbelong;
> referenceClass: TwittAR.Group;
> mappingCriteria: (Glorp.Join
>     from: (table fieldNamed: 'id')
>     to: (linkTable fieldNamed: 'user_id')).
>
> tableForGROUPS: aTable
>
> | owner |
> (aTable createFieldNamed: 'id' type: platform sequence) bePrimaryKey.
> aTable createFieldNamed: 'name' type: platform text.
> owner := aTable createFieldNamed: 'user_id' type: platform int4.
> aTable addForeignKeyFrom: owner to: ((self tableNamed: 'USERS') fieldNamed:
> 'id').
>
> tableForUSERS: aTable
>
> (aTable createFieldNamed: 'id' type: platform sequence) bePrimaryKey.
> aTable createFieldNamed: 'username' type: platform text.
> aTable createFieldNamed: 'password' type: platform text
>
> tableForGROUP_HAS_USER: aTable
>
> | groupKey userKey |
> "(aTable createFieldNamed: 'id' type: platform sequence) bePrimaryKey."
> userKey := aTable createFieldNamed: 'user_id' type: platform int4.
> aTable addForeignKeyFrom: userKey to: ((self tableNamed: 'USERS')
> fieldNamed: 'id').
> groupKey := aTable createFieldNamed: 'group_id' type: platform int4.
> aTable addForeignKeyFrom: groupKey to: ((self tableNamed: 'GROUPS')
> fieldNamed: 'id'
>
>
> Thank you very much!
>
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>
> Thank you for your answer Alan!
>
> I will consider your suggestions!
>
> What is the best way to map many to many relationship? I can not figure out
> how to specify the association table...
>
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>
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