/// <summary>
/// 通过左实体数据源和右实体数据源，来找到它们之间的第一个的引用属性，用以构造一个连接。
/// </summary>
/// <param name="left">拥有引用关系的左数据源。</param>
/// <param name="right">右实体数据源。</param>
/// <returns></returns>
public IJoin Join(
ITableSource left,
ITableSource right
)
{
//通过实体的对比，找到从左实体到右实体之间的第一个的引用属性。
var rightEntity = right.EntityRepository.EntityType;
var properties = left.EntityRepository.EntityMeta.ManagedProperties.GetCompiledProperties();
for (int i = 0, c = properties.Count; i < c; i++)
{
var refProperty = properties[i] as IRefEntityProperty;
if (refProperty != null && refProperty.RefEntityType == rightEntity)
{
var condition = this.Constraint(
left.Column(refProperty.RefIdProperty),
right.Column(Entity.IdProperty)
);
var joinType = refProperty.Nullable ? JoinType.LeftOuter : JoinType.Inner;
return(Join(left, right, condition, joinType));
}
}
throw new InvalidProgramException(string.Format(
"没有从 {0} 到 {1} 的引用关系，请指定具体的对比条件。", left.GetName(), right.GetName()
));
}