/// <summary>
/// Create a LearningStoreItemIdentifier from some data within a row of a
/// LogableSqlCommand
/// </summary>
/// <param name="command">The LogableSqlCommand. The current position is
/// not modified.</param>
/// <param name="startingColumn">The index of the first column to be
/// examined. On exit, this index contains the last column examined
/// plus one.</param>
/// <param name="itemType">Information about the identifier type to be
/// created.</param>
/// <returns>The<Typ>LearningStoreItemIdentifier</Typ>, or null if
/// a value is not found.</returns>
/// <remarks>Only examines one column. Assumes that the column contains
/// an int64 value, containing the key of the Id. If the column is
/// non-null, a LearningStoreItemIdentifier is returned. If the
/// column is null, null is returned.
/// </remarks>
private static LearningStoreItemIdentifier ReadItemIdentifierColumns(LogableSqlCommand command,
ref int startingColumn, LearningStoreItemType itemType)
{
if (command.IsDBNull(startingColumn))
{
startingColumn++;
return(null);
}
else
{
long idkey = command.GetInt64(startingColumn);
startingColumn++;
return(new LearningStoreItemIdentifier(itemType.Name, idkey));
}
}
/// <summary>
/// Create a LearningStoreItemIdentifier from a result within a LogableSqlCommand
/// </summary>
/// <param name="command">The LogableSqlCommand. On exit, the entire
/// current result has been read.</param>
/// <param name="itemType">Information about the item type that should be read.</param>
/// <returns>The<Typ>LearningStoreItemIdentifier</Typ></returns>
/// <remarks>Assumes that the result has one rows. Assumes that the
/// columns within the row contain exactly the correct data
/// for the <Mth>ReadItemIdentifierColumns</Mth> method.</remarks>
public static LearningStoreItemIdentifier ReadItemIdentifierResult(LogableSqlCommand command, LearningStoreItemType itemType)
{
// Check input parameters
if (command == null)
{
throw new LearningComponentsInternalException("LSTR1000");
}
if (itemType == null)
{
throw new LearningComponentsInternalException("LSTR1010");
}
if (!command.Read())
{
throw new LearningComponentsInternalException("LSTR1020");
}
// Start at the first column
int startingColumn = 0;
// Read the item
LearningStoreItemIdentifier id = ReadItemIdentifierColumns(command,
ref startingColumn, itemType);
// Verify that the correct number of values are in the row
if (command.GetFieldCount() != startingColumn)
{
throw new LearningComponentsInternalException("LSTR1030");
}
if (command.Read())
{
throw new LearningComponentsInternalException("LSTR1040");
}
return(id);
}
