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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2007, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id:Relation.scala 6853 2006-03-20 16:58:47 +0100 (Mon, 20 Mar 2006) dubochet $
package scala.dbc.result
/** An ISO-9075:2003 (SQL) table. This is equivalent to a relation in the
* relational model. */
abstract class Relation extends AnyRef with Iterable[Tuple] {
/** The statement that generated this relation. */
def statement: scala.dbc.statement.Relation
/** A JDBC result containing this relation. */
protected def sqlResult: java.sql.ResultSet
/** A JDBC metadata object attached to the relation. */
protected def sqlMetadata: java.sql.ResultSetMetaData = sqlResult.getMetaData()
/** Metadata about all fields in a tuple of the relation. */
def metadata: List[FieldMetadata] =
for (count <- List.range(1, sqlMetadata.getColumnCount()+1)) yield
new FieldMetadata {
val name: String = sqlMetadata.getColumnName(count)
val index: Int = count
val datatype: DataType = dbc.datatype.Factory.create(sqlMetadata,count)
val catalog: String = sqlMetadata.getCatalogName(count)
val schema: String = sqlMetadata.getSchemaName(count)
val table: String = sqlMetadata.getTableName(count)
}
/** Metadata about the field at the given index. If there is no such
* field <code>None</code> is returned instead. */
def metadataFor (index:Int): Option[FieldMetadata] =
try {Some(metadata(index))} catch {case e => None}
/** Metadata about the field with the given column name. If there is no
* such field, <code>None</code> is returned instead. */
def metadataFor (name:String): Option[FieldMetadata] =
metadata.find(f=>(f.name==name));
/** An iterator on the tuples of the relation.
* <h3>Caution</h3> A Relation only has one single iterator, due to limitations
* in DBMS. This means that if this method is called multiple times, all returned
* iterators will share the same state. */
def elements: Iterator[Tuple] = new Iterator[Tuple] {
protected val result: java.sql.ResultSet = Relation.this.sqlResult
def hasNext: Boolean = !(result.isLast())
def next: Tuple = {
if (result.next()) {
new Tuple {
val me = this
val originatingRelation = Relation.this
val fields: List[Field] = for (fieldMetadata <- metadata) yield
new Field {
val metadata = fieldMetadata
val content = dbc.value.Factory.create(result,metadata.index,metadata.datatype)
val originatingTuple = me
}
}
} else error("next on empty iterator")
}
}
}
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