Using Lift with Squeryl, how to I filter on a property of a parent class?

[Shafique Jamal]

Hello all,

I am using lift with Squeryl, and I'm having trouble formulating a query. 

I have two tables: pkg and item. item has a foreign key to the pkg table. One pkg can have many items. Items in a pkg have a unique lineNumber (though items of different packages can have the same lineNumber) 

My model classes (I am I using the right terminology?) look like the following:

class Pkg extends Record[...

val id = ...

val pkgNumber = some string field

...

lazy val items = DBSchema.pkgToItems.left(this)

class Item extends Record[...

val id = ...

val lineNumber = StringField(...)

val pkgid = ForeignKeyField(...)

lazy val pkgs = DBSchema.pkgToItems.right(this)

Object DBSchema extends Schema {

val pkgs = table[Pkg]

val items = table[Item]

val pkgToItems = oneToManyRelation(pkgs, items).via((pkg, item) => pkg.id === item.pkgid)

}

Here is what I would like to do: given (a) a pkgNumber, and (b) a lineItem number, find the Item. 

Here is where I am stuck:

  def byLineNumber(pkgNumber:String, lineNumber:String):Option[Item] = {

    DBSchema.items.where(_.lineNumber === lineNumber)

      .where(XXX)

      .headOption

  } 

what should XXX look like? perhaps: _.pkgs.where(_.pkgNumber == pkgNumber).isDefined?

This doesn't look right, but I'm not sure. Any suggestions on the proper way to do this?

Many thanks,

[David Whittaker]

Squeryl queries look very much like SQL. You can find more information and examples here: http://squeryl.org/selects.html. Similar to SQL, what you need is a where clause that contains two predicates concatenated with an and.

def byLineNumber(pkgNumber:String, lineNumber:String): Option[Item

] = {
    from(DBSchema.items)(i => where (i.pkgid === pkgNumber and i.lineNumber === lineNumber) select(i)).headOption

}

​

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[Shafique Jamal]

Hello David,

Ah, I see now. Many thanks for this response.

Cheers,

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