我正在使用内置的 z80 导航控件,这里是演示链接: Z80 Navigation Menu
如果有人看到这个控件,它有一个对象来创建菜单,比如父菜单和在它下面的子菜单。类似于以下内容:
public List<NavBarItem> sampleDynamicNav; //List of navbar objects
public DemoItems()
{
//Create object instance here and assign the parent as well child menus here
sampleDynamicNav = new List<NavBarItem> {
new NavBarItem {ID = 1, Text = "UserInfo", Icon = new ItemIcon {Default = SampleProject.Properties.Resources.nav_new_home, Hover = SampleProject.Properties.Resources.nav_new_home, Selected = SampleProject.Properties.Resources.nav_new_home}, ToolTip = "tooltip Main Menu", Height = 40,
Icon = new ItemIcon {Default = SampleProject.Properties.Resources.nav_new_home, Hover = SampleProject.Properties.Resources.nav_new_home, Selected = SampleProject.Properties.Resources.nav_new_home }, ToolTip = "tooltip Desktop"},
Childs = new List<NavBarItem> {
new NavBarItem {ID = 41, Text = "Add/Edit Users", Height = 30 },
new NavBarItem {ID = 42, ParentID = 1, Text = "Inactive User", Height = 30}
};
}
如果我们静态分配菜单,这就非常简单了。但我坚持了下来,当尝试动态添加它们时,我的意思是从数据库创建菜单,如下所示:
public DemoItems()
{
foreach (var parent in GetParent("USER-0001"))
{
foreach (var child in GetChild(parent.MenuNo))
{
sampleDynamicNav = new List<NavBarItem> {
new NavBarItem {
ID = parent.MenuNo, Text = parent.MenuName, Icon = new ItemIcon {Default = SampleProject.Properties.Resources.nav_new_home, Hover = SampleProject.Properties.Resources.nav_new_home, Selected = SampleProject.Properties.Resources.nav_new_home}, ToolTip = "tooltip Main Menu", Height = 40,
Childs = new List<NavBarItem> {
new NavBarItem {ID = child.MenuNo, ParentID = parent.MenuNo, Text = child.MenuName, Height = 30 },
}
}
};
}
}
}
通过上面的代码,它应该至少在导航栏中获取父菜单。现在,将子菜单放在一边,它在导航栏中显示一个父菜单,如下所示:
但它应该像下面这样,因为有两个父菜单并使用 foreach
循环迭代列表(GetParents() 返回对象列表):
我不知道我是否需要为此做任何其他事情,想知道我是否可以循环浏览导航栏的子属性,如下所示:
foreach (var child in GetChild(parent.MenuNo))
{
Childs = new List<NavBarItem> {
new NavBarItem {ID = child.MenuNo, ParentID = parent.MenuNo, Text = child.MenuName, Height = 30 },
}
注意:当尝试使用循环迭代子属性时,它会立即抛出错误。第二个内部循环工作并取出子菜单但是说,父菜单有两个子菜单,它当时返回 1。我调试了列表,它像往常一样返回两个父菜单,但没有显示在导航栏中。
GetParents 方法:
/**Get Menu Details - Starts**/
public IEnumerable<UserViewModel> GetParent(string empNo)
{
List<UserViewModel> lstUser = new List<UserViewModel>();
string query = "SELECT DISTINCT M.PARENT, M.MENUNO, M.MENUNAME FROM (SELECT DISTINCT M.MENUNO, M.MENUNAME, M.PARENT " +
"FROM USER_DETAILS U INNER JOIN USER_GROUP_DETAILS UG ON UG.EMPNO = U.EMPNO " +
"INNER JOIN ASSIGN_MENU_DETAILS AM ON AM.GROUPNO = UG.GROUPNO INNER JOIN MENU_DETAILS M " +
"ON M.MENUNO = AM.MENUNO WHERE U.EMPNO = '" + empNo + "' " +
"UNION ALL " +
"SELECT DISTINCT M.MENUNO, M.MENUNAME, " +
"M.PARENT FROM MENU_DETAILS M " +
"INNER JOIN MENU_DETAILS C " +
"ON C.PARENT = M.MENUNO) m WHERE M.PARENT = '0' ORDER BY M.PARENT";
DataTable dt = SelectData(query);
if (dt != null && dt.Rows.Count > 0)
{
foreach (DataRow dr in dt.Rows)
{
UserViewModel bo = new UserViewModel();
bo.Parent = Convert.ToInt32(dr["PARENT"].ToString());
bo.MenuNo = Convert.ToInt32(dr["MENUNO"].ToString());
bo.MenuName = dr["MENUNAME"].ToString();
lstUser.Add(bo);
}
}
return lstUser;
}
/**Get Menu Details - Ends**/
最佳答案
您可以创建以下辅助方法并使用它们创建 List<NavBarItem
接受任何类型的数据源作为输入,包括 DataTable
, List<YourEntity>
或任何其他 IEnumerable<T>
.
因此,无论您拥有何种数据存储,都可以使用以下方法。
它依赖于递归算法来创建树。要从任何类型的数据源创建树,您需要了解以下信息:
- 数据来源
- 如何检测数据源中的项目是否为根项目
- 如何在数据源中查找项目的子项目
- 如何从数据源项创建树项。
以下方法创建 NavBarItem
的列表通过询问以上信息的层次结构:
private IEnumerable<NavBarItem> GetNavBarItems<T>(
IEnumerable<T> source,
Func<T, Boolean> isRoot,
Func<T, IEnumerable<T>, IEnumerable<T>> getChilds,
Func<T, NavBarItem> getItem)
{
IEnumerable<T> roots = source.Where(x => isRoot(x));
foreach (T root in roots)
yield return ConvertEntityToNavBarItem(root, source, getChilds, getItem); ;
}
private NavBarItem ConvertEntityToNavBarItem<T>(
T entity,
IEnumerable<T> source,
Func<T, IEnumerable<T>, IEnumerable<T>> getChilds,
Func<T, NavBarItem> getItem)
{
NavBarItem node = getItem(entity);
var childs = getChilds(entity, source);
foreach (T child in childs)
node.Childs.Add(ConvertEntityToNavBarItem(child, source, getChilds, getItem));
return node;
}
示例
我假设您已将数据加载到以下结构中:
var dt = new DataTable();
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("ParentId", typeof(int));
dt.Rows.Add(1, "Menu 1", DBNull.Value);
dt.Rows.Add(11, "Menu 1-1", 1);
dt.Rows.Add(111, "Menu 1-1-1", 11);
dt.Rows.Add(112, "Menu 1-1-2", 11);
dt.Rows.Add(12, "Menu 1-2", 1);
dt.Rows.Add(121, "Menu 1-2-1", 12);
dt.Rows.Add(122, "Menu 1-2-2", 12);
dt.Rows.Add(123, "Menu 1-2-3", 12);
dt.Rows.Add(124, "Menu 1-2-4", 12);
dt.Rows.Add(2, "Menu 2", DBNull.Value);
dt.Rows.Add(21, "Menu 2-1", 2);
dt.Rows.Add(211, "Menu 2-1-1", 21);
然后将其转换为 List<NavBarItem>
,您可以使用以下代码:
var source = dt.AsEnumerable();
var list = GetNavBarItems(
source,
(r) => r.Field<int?>("ParentId") == null,
(r, s) => s.Where(x => x.Field<int?>("ParentId") == r.Field<int?>("Id")),
(r) => new NavBarItem()
{
ID = r.Field<int>("Id"),
Text = r.Field<string>("Name"),
ParentID = r.Field<int?>("ParentId")
}).ToList();
因此,您将具有以下结构:
Menu 1
Menu 1-1
Menu 1-1-1
Menu 1-1-2
Menu 1-2
Menu 1-2-1
Menu 1-2-2
Menu 1-2-3
Menu 1-2-4
Menu 2
Menu 2-1
Menu 2-1-1
注意
对于那些不想安装包,但想测试结构的人,可以使用下面的NavBarItem
类:
public class NavBarItem
{
public NavBarItem()
{
Childs = new List<NavBarItem>();
}
public int ID { get; set; }
public int? ParentID { get; set; }
public string Text { get; set; }
public List<NavBarItem> Childs { get; set; }
public override string ToString()
{
return Text;
}
}
关于c# - 在每个循环迭代中创建对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53911780/