自定义数据绑定

自定义数据绑定
新建自定义数据模型
  public class FileCollectionModelBinder : IModelBinder {

        public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) {
            if (controllerContext == null) {
                throw new ArgumentNullException("controllerContext");
            }
            if (bindingContext == null) {
                throw new ArgumentNullException("bindingContext");
            }

            List<HttpPostedFileBase> files = GetFiles(controllerContext.HttpContext.Request.Files, bindingContext.ModelName);
            if (files.Count == 0) {
                return null;
            }

            switch (GetCollectionType(bindingContext.ModelType)) {
                case CollectionType.Array:
                    return files.ToArray();

                case CollectionType.Collection:
                    return new Collection<HttpPostedFileBase>(files);

                case CollectionType.List:
                    return files;

                default:
                    throw new InvalidOperationException(String.Format(
                        CultureInfo.CurrentUICulture, "This model binder does not support the model type '{0}'.", bindingContext.ModelType.FullName));
            }
        }

        private static HttpPostedFileBase ChooseFileContentOrNull(HttpPostedFileBase theFile) {
            bool fileContainsContent = (theFile.ContentLength != 0 || !String.IsNullOrEmpty(theFile.FileName));
            return (fileContainsContent) ? theFile : null;
        }

        private static CollectionType GetCollectionType(Type targetType) {
            if (targetType == typeof(IEnumerable<HttpPostedFileBase>) || targetType == typeof(HttpPostedFileBase[])) {
                return CollectionType.Array;
            }
            if (targetType == typeof(ICollection<HttpPostedFileBase>) || targetType == typeof(Collection<HttpPostedFileBase>)) {
                return CollectionType.Collection;
            }
            if (targetType == typeof(IList<HttpPostedFileBase>) || targetType == typeof(List<HttpPostedFileBase>)) {
                return CollectionType.List;
            }
            return CollectionType.Unknown;
        }

        private static List<HttpPostedFileBase> GetFiles(HttpFileCollectionBase fileCollection, string key) {
            // first, check for any files matching the key exactly
            List<HttpPostedFileBase> files = fileCollection.AllKeys
                .Select((thisKey, index) => (String.Equals(thisKey, key, StringComparison.OrdinalIgnoreCase)) ? index : -1)
                .Where(index => index >= 0)
                .Select(index => fileCollection[index])
                .ToList();

            if (files.Count == 0) {
                // then check for files matching key[0], key[1], etc.
                for (int i = 0; ; i++) {
                    string subKey = String.Format(CultureInfo.InvariantCulture, "{0}[{1}]", key, i);
                    HttpPostedFileBase thisFile = fileCollection[subKey];
                    if (thisFile == null) {
                        break;
                    }
                    files.Add(thisFile);
                }
            }

            // if an <input type="file" /> element was rendered on the page but the user did not select a file before posting
            // the form, null out that entry in the list.
            List<HttpPostedFileBase> filteredFiles = files.ConvertAll((Converter<HttpPostedFileBase, HttpPostedFileBase>)ChooseFileContentOrNull);
            return filteredFiles;
        }

        public static void RegisterBinder(ModelBinderDictionary binders) {
            FileCollectionModelBinder binder = new FileCollectionModelBinder();

            binders[typeof(HttpPostedFileBase[])] = binder;
            binders[typeof(IEnumerable<HttpPostedFileBase>)] = binder;
            binders[typeof(ICollection<HttpPostedFileBase>)] = binder;
            binders[typeof(IList<HttpPostedFileBase>)] = binder;
            binders[typeof(Collection<HttpPostedFileBase>)] = binder;
            binders[typeof(List<HttpPostedFileBase>)] = binder;
        }

        private enum CollectionType {
            Array,
            Collection,
            List,
            Unknown
        }

使用方式
 public ActionResult ProcessFiles([ModelBinder(typeof(FileCollectionModelBinder))] IList<HttpPostedFileBase> files)
   
        //public ActionResult ProcessFiles(   IList<HttpPostedFileBase> files)
        {
            foreach (HttpPostedFileBase file in files)
            {
                if (file.ContentLength != 0)
                {
                    string[] filesplit = file.FileName.Split( '//' );
                    string fileName = filesplit[filesplit.Length - 1];

                    file.SaveAs(Server.MapPath(@"/Images/") + fileName);               
                }
            }

            return RedirectToAction("ImageList");
        }

        public ActionResult ImageList()
        {
            var model = Directory.GetFiles(Server.MapPath(@"/Images/")).AsEnumerable ();
           
            return View(model);
        }


在index页面
<<p>
        可以批量上传照片到指定目录，然后显示照片列表。
    </p>
   
    <% using( var form = Html.BeginForm(
                                         "ProcessFiles",
                                         "Home",
                                         FormMethod.Post,
                                         new { enctype = "multipart/form-data"}))
 {%>
    <p>
    <input type="file" name="files" />
    <br/>
    <input type="file" name="files" />
    <br/>
    <input type="file" name="files" />
    </p>
 
    <input type="submit" value="批量上载照片" />

<% }%>


<% =Html.ActionLink ("照片列表","ImageList") %>

在ImageList页面
  <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<string>>" %>

    <% foreach (string fileName in Model.ToList ()) {   %>
       
        <img src ="<% =fileName %>"   alt ="image"  width="150"  height="100"/>
            
     <% } %>