正文
tree状数据叶子节点与根节点等的递归转换
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做项目时经常遇到树状层级数据。从各个层级数据的转换查询等。场景如行业类别的多层级，行政区层级，检查项类别层级等等。
数据结构如 Id Name ParentId
#region area树状节点的转化
public List<Area> ConvertToLeafChildAreas(List<int> areaIds)
{
var allAreas = GetNewAreas().ToList();
List<Area> leafChildren = new List<Area>();
foreach (var areaId in areaIds)
{
leafChildren.AddRange(GetLeafChildAreas(areaId, allAreas));
}
return leafChildren;
}
/// <summary>
/// 根据父ID获取所有的最小地区
/// </summary>
/// <param name="parentId"></param>
/// <param name="allAreas"></param>
/// <returns></returns>
public List<Area> GetLeafChildAreas(int parentId,List<Area> allAreas)
{
List<Area> leafChildren = new List<Area>();
var sons = allAreas.Where(o => o.ParentId == parentId).ToList();
if (sons.Any())
{
foreach (var item in sons)
{
leafChildren.AddRange(GetLeafChildAreas(item.Id, allAreas));
}
}
else
{
var currentArea = allAreas.FirstOrDefault(m=>m.Id== parentId);
leafChildren.Add(currentArea);
}
return leafChildren;
}
public List<Area> ConvertToRootAreas(List<int> childAreaIds)
{
var allAreas = GetNewAreas().ToList();
var childAreas = allAreas.Where(m => childAreaIds.Contains(m.Id)).ToList();
List<Area> root = new List<Area>();
foreach (var childArea in childAreas)
{
root.Add(GetRootArea(childArea, allAreas));
}
return root.Distinct().ToList();
}
/// <summary>
/// 根据子ID获取所有的最顶级地区
/// </summary>
/// <param name="childArea"></param>
/// <param name="allAreas"></param>
/// <returns></returns>
public Area GetRootArea(Area childArea, List<Area> allAreas)
{
var parentArea = allAreas.FirstOrDefault(o => o.Id == childArea.ParentId);
if (parentArea==null) return childArea;
return GetRootArea(parentArea,allAreas);
}
#endregion
