Question

我正在尝试根据VS 2010的教程构建博客，并使用VS 2013我收到错误。任何帮助，将不胜感激。我的Foreach语句将不会执行..我收到一条错误，指出Foreach语句无法对类型为＆＃39; blog.Models.Tag＆＃39;的变量进行操作。因为blog.Models.Tag不包含Get Enumerator的公共定义...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using blog.Models;
using System.Text;

namespace blog.Controllers
{
    public class PostsController : Controller
    {
        private BlogModel model = new BlogModel();
        private const int PostsPerPage = 4;

        public ActionResult Index(int? id)
        {
            int pageNumber = id ?? 0;
            IEnumerable<Post> posts =
                (from post in model.Posts
                where post.DateTime < DateTime.Now
                orderby post.DateTime descending
                select post).Skip(pageNumber * PostsPerPage).Take(PostsPerPage + 1);
            ViewBag.IsPreviousLinkVisible = pageNumber > 0;
            ViewBag.IsNextLinkVisible = posts.Count() > PostsPerPage;
            ViewBag.PageNumber = pageNumber;
            ViewBag.IsAdmin = IsAdmin;
            return View(posts.Take(PostsPerPage));
        }

        public ActionResult Details(int id)
        {
            Post post = GetPost(id);
            ViewBag.IsAdmin = IsAdmin;
            return View(post);
        }

        [ValidateInput(false)]
        public ActionResult Comment(int id, string name, string email, string body)
        {
            Post post = GetPost(id);
            Comment comment = new Comment();
            comment.Post = post;
            comment.Time = DateTime.Now;
            comment.Name = name;
            comment.Email = email;
            comment.Body = body;
            model.Comments.Add(comment);
            model.SaveChanges();
            return RedirectToAction("Details", new { id = id });
        }

        public ActionResult Tags(string id)
        {
            Tag Tag = (dynamic)GetTag(id);
            ViewBag.IsAdmin = IsAdmin;
            return View("Index", Tag.Posts);
        }

        [ValidateInput(false)]
        public ActionResult Update(int? id, string title, string body, DateTime dateTime, string tags)
        {
            if(!IsAdmin)
            {
                return RedirectToAction("Index");
            }

            Post post = GetPost(id);
            post.Title = title;
            post.Body = body;
            post.DateTime = dateTime;
            post.Tags.Clear();

            tags = tags ?? string.Empty;
            string[] tagNames = tags.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            foreach(string tagName in tagNames)
            {
                post.Tags.Add(GetTag(tagName));
            }

            if(!id.HasValue)
            {
                model.Posts.Add(post);
            }
            model.SaveChanges();
            return RedirectToAction("Details", new { id = post.Id });
        }

        public ActionResult Edit(int? id)
        {
            Post post = GetPost(id);
            StringBuilder tagList = new StringBuilder();

            foreach(Tag tag in post.Tags)
            {
                tagList.AppendFormat("{0} ", tag.Name);
            }

            ViewBag.Tags = tagList.ToString();
            return View(post);
        }

         private object GetTag(string tagName)
         {
            return model.Tags.Where(x => x.Name == tagName).FirstOrDefault() ?? new Tag() {Name = tagName};
         }

        private Post GetPost(int? id)
        {
            return id.HasValue ? model.Posts.Where(x => x.Id == id).First() : new Post() { Id = -1 };
        }

        //TODO: Fix this later
        public bool IsAdmin { get { return true; } }
    }
}

这是我的 Tag.cs

namespace blog.Models
{
    using System;
    using System.Collections.Generic;


    public partial class Tag
    {
        public Tag()
        {
            this.Posts = new HashSet<Post>();
        }

        public int Id { get; set; }
        public string Name { get; set; }

        public virtual ICollection<Post> Posts { get; set; }

        internal void Clear()
        {
            //throw new NotImplementedException();
        }

        internal void Add(object p)
        {
            //throw new NotImplementedException();
        }
    }
}

这是我的Posts.cs

namespace blog.Models
{
    using System;
    using System.Collections.Generic;

    public partial class Post
    {
        public Post()
        {
            this.Comments = new HashSet<Comment>();
        }

        public int Id { get; set; }
        public string Title { get; set; }
        public System.DateTime DateTime { get; set; }
        public string Body { get; set; }

        public virtual ICollection<Comment> Comments { get; set; }
        public virtual Tag Tags { get; set; }
    }
}

Answer 1

Foreach只能在实现GetEnumerator的集合上完成，因为它使用此函数来获取＆＃34; next＆＃34;项目到foreach上。显然这个功能不存在。

foreach语句错误GetEnumerator

1 个答案: