/// <summary>
/// Gets a list of keys to group by.
/// </summary>
/// <remarks>
/// When converting an unnormalized set of data from a database view,
/// a new entity is only created when the grouping keys have changed.
/// </remarks>
/// <returns></returns>
private GroupingKeyCollection GetGroupingKeyColumns()
{
// Get primary keys for this parent entity
GroupingKeyCollection groupingKeyColumns = new GroupingKeyCollection();
groupingKeyColumns.PrimaryKeys.AddRange(Columns.PrimaryKeys);
// The following conditions should fail with an exception:
// 1) Any parent entity (entity with children) must have at least one PK specified or an exception will be thrown
// 2) All 1-M relationship entities must have at least one PK specified
// * Only 1-1 entities with no children are allowed to have 0 PKs specified.
if ((groupingKeyColumns.PrimaryKeys.Count == 0 && _children.Count > 0) ||
(groupingKeyColumns.PrimaryKeys.Count == 0 && IsChild && _relationship.RelationshipInfo.RelationType == RelationshipTypes.Many) ||
groupingKeyColumns.PrimaryKeys.Count == 0 && !IsChild)
{
throw new MissingPrimaryKeyException(string.Format("There are no primary key mappings defined for the following entity: '{0}'.", this.EntityType.Name));
}
// Add parent's keys
if (IsChild)
{
groupingKeyColumns.ParentPrimaryKeys.AddRange(Parent.GroupingKeyColumns);
}
return(groupingKeyColumns);
}
/// <summary>
/// Concatenates the values of the GroupingKeys property and compares them
/// against the LastKeyGroup property. Returns true if the values are different,
/// or false if the values are the same.
/// The currently concatenated keys are saved in the LastKeyGroup property.
/// </summary>
/// <param name="reader"></param>
/// <returns></returns>
public bool IsNewGroup(DbDataReader reader, bool useAltName)
{
bool isNewGroup = false;
// Get primary keys from parent entity and any one-to-one child entites
GroupingKeyCollection groupingKeyColumns = this.GroupingKeyColumns;
// Concatenate column values
KeyGroupInfo keyGroupInfo = groupingKeyColumns.CreateGroupingKey(reader, useAltName);
if (!keyGroupInfo.HasNullKey && !_entityReferences.ContainsKey(keyGroupInfo.GroupingKey))
{
isNewGroup = true;
}
return(isNewGroup);
}