如何构建保存在数据库

时间:2015-11-09 06:21:58

标签: c# asp.net-mvc sql-server-2008 knockout.js linq-to-entities

我遇到了问题。我正确配置了数据库,图像正确保存在数据库中,但不知道如何构建保存在数据库中的图像的URL,因为我必须将其提供给用于绑定的挖空视图模型。

  public JsonResult GetPosts()
    {
        var ret = (from post in db.Posts.ToList()
                   orderby post.PostedDate descending
                   select new
                   {
                       Message = post.Message,
                       PostedBy = post.PostedBy,
                       PostedByName = post.ApplicationUser.UserName,
 // having problem at this line dont know how to construct url at this line as i have to supply url
 // (String type to the PostedByAvatar)
                       PostedByAvatar = db.Files.SingleOrDefault(s => s.ApplicationUserId == post.PostedBy),
                       PostedDate = post.PostedDate,
                       PostId = post.PostId,
                   }).AsEnumerable();
        return Json(ret, JsonRequestBehavior.AllowGet);
    }

这是淘汰赛的功能--------

    function Post(data) {
var self = this;
data = data || {};
self.PostId = data.PostId;
self.Message = ko.observable(data.Message || "");
self.PostedBy = data.PostedBy || "";
self.PostedByName = data.PostedByName || "";

self.PostedDate = getTimeAgo(data.PostedDate);
self.PostedByAvatar = data.PostedByAvatar || "";
self.error = ko.observable();
self.PostComments = ko.observableArray();

这是用数据库中的图像获取现有帖子,评论等的视图模型-----

    function viewModel() {
    var self = this;
    self.posts = ko.observableArray();
    self.newMessage = ko.observable();
    self.error = ko.observable();
    self.loadPosts = function () {
        // to load existing posts
        $.ajax({
            url: postApiUrl1,
            datatype: "json",
            contentType: "application/json",
            cache: false,
            type: 'Get'
        })

在我的视图页面上,这是一个用post------

加载图像的容器框
    <ul id="msgHolder" data-bind="foreach: posts">
    <li class="postHolder">
    <img data-bind="attr: { src: PostedByAvatar }">
    <p><a data-bind="text: PostedByName"></a>: <span data-bind=" html: Message"></span></p>

现在,将数据保存在数据库中的模型类是这样的。它有ApplicationUserId作为指向ApplicationUserClass的外键---

   public class File
   {
    [Key]
    public int FileId { get; set; }
    [StringLength(255)]
    public string FileName { get; set; }
    [StringLength(100)]
    public string ContentType { get; set; }
    public byte[] Content { get; set; }
    public FileType FileType { get; set; }
    public int ApplicationUserId { get; set; }
    public virtual ApplicationUser ApplicationUser { get; set; }
   }

和ApplicationUserClass是这样的---

  public class ApplicationUser : IdentityUser<int, CustomUserLogin, CustomUserRole, CustomUserClaim>
   {
    public ApplicationUser()
    {
        this.Posts = new HashSet<Post>();
        this.Files = new HashSet<File>();
    }
    public virtual ICollection<File> Files { get; set; }
    public virtual ICollection<Post> Posts { get; set; }

enter image description here

这是保存在database.Iow中的图像。现在,我想知道如何为保存在数据库中的图像构建url,因为我必须以字符串形式将其提供给视图模型。或者有任何方法比这更好。

这是我的Post类,它与ApplicationUser类有多对一关系,外键是PostedBy指向ApplicationUser类----

   public class Post
   {
    public Post()
    {
        this.PostComments = new HashSet<PostComment>();
    }
    [Key]
    public int PostId { get; set; }
    public string Message { get; set; }
    public int? PostedBy { get; set; }
    public System.DateTime PostedDate { get; set; }
    public virtual ICollection<PostComment> PostComments { get; set; }
    public virtual ApplicationUser ApplicationUser { get; set; }
}

1 个答案:

答案 0 :(得分:1)

虽然可以将Base64字符串作为src的{​​{1}}传递,但我认为最合理的方法是不从Ajax调用返回实际字节,而是创建一个url这将从服务器请求图像字节。

首先,添加将为图像数据提供的所需操作:

<img>

现在,将[HttpGet] public FileResult GetFileData(int fileId) { var file = db.Files.Single(x => x.FileId == fileId); return File(file.Content, file.ContentType); } 操作更改为GetPosts属性中的返回网址:

PostedByAvatar