bootstrapblazor数据库生成动态菜单的实现

通过数据库中的表实现动态菜单，可以分为以下几种

1、通过数据库菜单表直接生成菜单

2、通过数据库菜单表和用户权限表，按权限生成不同的菜单

为了简化，实体类直接用于查询数据，不作数据写入，MID是权限ID，菜单表如下

public class MyMenu
{
    [Key]
    public int ID { get; set; }
    public string? 菜单ID { get; set; }
    public string? 名称 { get; set; }
    public string? 图标 { get; set; }
    public string? url { get; set; }
    public string? 父菜单ID { get; set; }
}

CREATE TABLE [dbo].[系统菜单](
	[ID] [int] IDENTITY(1,1) NOT NULL,
	[菜单ID] [nvarchar](50) NULL,
	[名称] [nvarchar](50) NULL,
	[图标] [nvarchar](50) NULL,
	[URL] [nvarchar](50) NULL,
	[父菜单ID] [nvarchar](50) NULL,
	[MID] [nvarchar](50) NULL,
 CONSTRAINT [PK_系统菜单] PRIMARY KEY CLUSTERED 
(
	[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

查询菜单表如下，是一个视图，通过关联用户权限来实现不同权限生成不同的菜单

public class QMenu
{
    [Key]
    public int ID { get; set; }
    public string? 菜单ID { get; set; }
    public string? 名称 { get; set; }
    public string? 图标 { get; set; }
    public string? url { get; set; }
    public string? 父菜单ID { get; set; }

    public string? 用户名 { get; set; }
}

CREATE VIEW [dbo].[查询_菜单]
AS
SELECT   dbo.系统菜单.*, dbo.用户_权限.用户名
FROM      dbo.系统菜单 RIGHT OUTER JOIN
                dbo.用户_权限 ON dbo.系统菜单.MID = dbo.用户_权限.权限id
GO

在登录后加载菜单的地方，先读取顶级菜单，再遍历子菜单，isAdmin用来判断是否具有管理员权限，如果是管理员权限，则加载所有的菜单，否则只加载用户权限所具有的菜单。

 public List<MenuItem> GetTopMenu() 
 {
     var menus = new List<MenuItem>();
     List<MyMenu> M1;

     using (var context = new MyContext())
     {
         M1 = context.MyMenus
             .Where(i=>i.父菜单ID==null)
             .ToList();
     }
     //获取所有的顶级菜单
     foreach (var m in M1) 
     {
         var m_1 = new MenuItem();
         m_1.Text = m.名称;
         m_1.Icon = m.图标;
         m_1.Url = m.url;
         m_1.Id = m.菜单ID;
         menus.Add(m_1);
     }

     //遍历子菜单
     
     if (isAdmin == true) 
     {
         foreach (var menuItem in menus)
         {
             menuItem.Items = GetSubMenu(menuItem.Id,true);
         }
     }
     if (isAdmin == false)
     {
         foreach (var menuItem in menus)
         {
             menuItem.Items = GetSubMenu(menuItem.Id);
         }
     }
     //清理掉没有子菜单的顶级菜单
     for (var i = menus.Count - 1; i >= 1; i--) 
     {
         var num=menus[i].Items.Count();
         if (num <= 0) 
         {
             menus.RemoveAt(i);
         }
     }
     //增加退出菜单，因为退出菜单是顶级菜单，上边被清理掉了
     menus.Add(new() { Text = "退出登录", Icon = "fas fa-display", Url = "/api/Account/Logout" });
     return menus;
 }

遍历子菜单

 private List<MenuItem> GetSubMenu(string parentID) 
 {
     var menu = new List<MenuItem>();
     List<QMenu> M1;
     using (var context = new MyContext())
     {
         M1 = context.QMenus
        .Where(p => p.父菜单ID == parentID)
        .Where(p => p.用户名 == UserName)
        .ToList();
     }

     foreach (var m in M1) 
     {
         var p = new MenuItem();
         p.Text=m.名称;
         p.Icon = m.图标;
         p.Url = m.url;
         p.Id = m.菜单ID;
         p.Items = GetSubMenu(m.菜单ID);
         menu.Add(p);
     }
     return menu;
 }

 private List<MenuItem> GetSubMenu(string parentID,bool admin)
 {
     var menu = new List<MenuItem>();
     List<MyMenu> M1;
     using (var context = new MyContext())
     {
         M1 = context.MyMenus
        .Where(p => p.父菜单ID == parentID)
        .ToList();
     }

     foreach (var m in M1)
     {
         var p = new MenuItem();
         p.Text = m.名称;
         p.Icon = m.图标;
         p.Url = m.url;
         p.Id = m.菜单ID;
         p.Items = GetSubMenu(m.菜单ID,admin);
         menu.Add(p);
     }
     return menu;
 }

好了，把返回值赋给菜单就可以使用了。

private List<MenuItem>? Menus { get; set; }
protected override async void OnInitialized()
{
    base.OnInitialized();
    var user = (await Auth.GetAuthenticationStateAsync()).User;
    UserName = user.Identity.Name;
    
    string qx ="有";
    if (qx == "有")
    {
        isAdmin = true;
    }
      Menus = GetTopMenu();
 }

最后的效果如下，还是挺好用的