I like how the "Html.ValidationMessageFor" and "Html.ValidationSummary" helpers work for validating textboxes, such as for required fields. Is there some way I can accomplish the same thing for a file input control? From the examples I've seen so far you
cannot directly bind a file upload to your model, so I can't use the [Required] attribute that I am using for the textboxes. Any suggestions/examples on how you'd accomplish this.
(I am using MVC 2 & .Net 3.5 in Visual Studio 2010)
And of course, the HtmlHelper Extensions for a "file box"
/// <summary>
/// Returns a file input element by using the specified HTML helper and the name of the form field.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param>
/// <returns>An input element that has its type attribute set to "file".</returns>
public static string FileBox(this HtmlHelper htmlHelper, string name)
{
return htmlHelper.FileBox(name, (object) null);
}
/// <summary>
/// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>An input element that has its type attribute set to "file".</returns>
public static string FileBox(this HtmlHelper htmlHelper, string name, object htmlAttributes)
{
return htmlHelper.FileBox(name, new RouteValueDictionary(htmlAttributes));
}
/// <summary>
/// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>An input element that has its type attribute set to "file".</returns>
public static string FileBox(this HtmlHelper htmlHelper, string name, IDictionary<String, Object> htmlAttributes)
{
var tagBuilder = new TagBuilder("input");
tagBuilder.MergeAttributes(htmlAttributes);
tagBuilder.MergeAttribute("type", "file", true);
tagBuilder.MergeAttribute("name", name, true);
tagBuilder.GenerateId(name);
ModelState modelState;
if (htmlHelper.ViewData.ModelState.TryGetValue(name, out modelState))
{
if (modelState.Errors.Count > 0)
{
tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName);
}
}
return tagBuilder.ToString(TagRenderMode.SelfClosing);
}
I know I should figure it out myself, but would it be possible to overload that "FileBox" helper of mine to be able to call it with say <%: html.FilBox(model=>model.FileName) %> ?
Thanks for this great example of an htlmhelper extension
I can see how you obtain the path to a file to upload but I don't see how the file is uploaded. The standard upload file control returns an HttpPostedFileBase object and uploads the file but your control returns just the path to the file. There seems
to be something missing in your action method. Can you fill me in?
I am not sitting in front of the code where I used this right now, but I the only reason for this helper was to validate that a file existed (i.e. has a filename) and report any error back to the view. I think I still had to get the actual file as you normally
would without this helper method.
Thanks the reply. I agree, the FileBox helper works well to validate that the file exists, particularly with your refinement.
However the only approach I have used previously to upload files is to include a file upload control and work with the HttpPostedFileBase object.SaveAs to actually upload and save the file to a web server directory. There are tons of documentation and
examples on this approach on msdn, asp.net, etc. However this approach no longer works once you replace the upload control with the FileBox control.
I have found nothing that demonstrates how to upload a file from a client machine to a web server starting the the fully qualified path on the client machine. If there is a "normal" approach that I am ignorant of, I'd appeciate being pointed in the right
direction.
Thanks Krokonoster you really helped me there so I would like to return the favour with my slightly modified version that will work with the new MVC2
<%: %> syntax. I have added the expression version with a modification to the name
FileBoxFor rather than FileBox for consistency and also the
MvcHtmlString return value:
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Web.Mvc;
using System.Web.Routing;
namespace Ewdev.Web
{
/// <summary>
/// Html helper extension for an Input file upload element
/// </summary>
public static class FileBoxHtmlHelperExtension
{
/// <summary>
/// Returns a file input element by using the specified HTML helper and the name of the form field.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name)
{
return htmlHelper.FileBox(name, (object)null);
}
/// <summary>
/// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name, object htmlAttributes)
{
return htmlHelper.FileBox(name, new RouteValueDictionary(htmlAttributes));
}
/// <summary>
/// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes.
/// </summary>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name, IDictionary<String, Object> htmlAttributes)
{
var tagBuilder = new TagBuilder("input");
tagBuilder.MergeAttributes(htmlAttributes);
tagBuilder.MergeAttribute("type", "file", true);
tagBuilder.MergeAttribute("name", name, true);
tagBuilder.GenerateId(name);
ModelState modelState;
if (htmlHelper.ViewData.ModelState.TryGetValue(name, out modelState))
{
if (modelState.Errors.Count > 0)
{
tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName);
}
}
return MvcHtmlString.Create(tagBuilder.ToString(TagRenderMode.SelfClosing));
}
/// <summary>
/// Returns a file input element by using the specified HTML helper and the name of the form field as an expression.
/// </summary>
/// <typeparam name="TModel">The type of the model.</typeparam>
/// <typeparam name="TValue">The type of the value.</typeparam>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression)
{
return htmlHelper.FileBoxFor<TModel, TValue>(expression, (object)null);
}
/// <summary>
/// Returns a file input element by using the specified HTML helper and the name of the form field as an expression.
/// </summary>
/// <typeparam name="TModel">The type of the model.</typeparam>
/// <typeparam name="TValue">The type of the value.</typeparam>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object htmlAttributes)
{
return htmlHelper.FileBoxFor<TModel, TValue>(expression, new RouteValueDictionary(htmlAttributes));
}
/// <summary>
/// Returns a file input element by using the specified HTML helper and the name of the form field as an expression.
/// </summary>
/// <typeparam name="TModel">The type of the model.</typeparam>
/// <typeparam name="TValue">The type of the value.</typeparam>
/// <param name="htmlHelper">The HTML helper instance that this method extends.</param>
/// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param>
/// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param>
/// <returns>
/// An input element that has its type attribute set to "file".
/// </returns>
public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, IDictionary<String, Object> htmlAttributes)
{
var name = ExpressionHelper.GetExpressionText(expression);
return htmlHelper.FileBox(name, htmlAttributes);
}
}
}
jedijohn82
Member
2 Points
19 Posts
MVC File Upload Validation
Jun 08, 2010 03:16 PM|LINK
I like how the "Html.ValidationMessageFor" and "Html.ValidationSummary" helpers work for validating textboxes, such as for required fields. Is there some way I can accomplish the same thing for a file input control? From the examples I've seen so far you cannot directly bind a file upload to your model, so I can't use the [Required] attribute that I am using for the textboxes. Any suggestions/examples on how you'd accomplish this.
(I am using MVC 2 & .Net 3.5 in Visual Studio 2010)
file upload asp.net mvc upload file
krokonoster
Contributor
3985 Points
1102 Posts
Re: MVC File Upload Validation
Jun 08, 2010 03:44 PM|LINK
I'm about to post a long piece of code (HtmlHelper), but it works for me.
First I do have a HtmlHelper extension method to render a file box (code at the bottom of the post)
Model
public class FileModel { [Required] public string FileName { get; set; } [Required] public string Description { get; set; } }Action Methods:
public ActionResult FileTest() { return View(); } [HttpPost] public ActionResult FileTest(FileModel model) { if(ModelState.IsValid) { return RedirectToAction("Index"); } return View(model); }View (the part that matter):
<div class="editor-label"> <%: Html.LabelFor(model => model.FileName) %> </div> <div class="editor-field"> <%= Html.FileBox("FileName") %> <%: Html.ValidationMessageFor(model => model.FileName) %> </div>And of course, the HtmlHelper Extensions for a "file box"
/// <summary> /// Returns a file input element by using the specified HTML helper and the name of the form field. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param> /// <returns>An input element that has its type attribute set to "file".</returns> public static string FileBox(this HtmlHelper htmlHelper, string name) { return htmlHelper.FileBox(name, (object) null); } /// <summary> /// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns>An input element that has its type attribute set to "file".</returns> public static string FileBox(this HtmlHelper htmlHelper, string name, object htmlAttributes) { return htmlHelper.FileBox(name, new RouteValueDictionary(htmlAttributes)); } /// <summary> /// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="member">System.Web.Mvc.ViewDataDictionary</see> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns>An input element that has its type attribute set to "file".</returns> public static string FileBox(this HtmlHelper htmlHelper, string name, IDictionary<String, Object> htmlAttributes) { var tagBuilder = new TagBuilder("input"); tagBuilder.MergeAttributes(htmlAttributes); tagBuilder.MergeAttribute("type", "file", true); tagBuilder.MergeAttribute("name", name, true); tagBuilder.GenerateId(name); ModelState modelState; if (htmlHelper.ViewData.ModelState.TryGetValue(name, out modelState)) { if (modelState.Errors.Count > 0) { tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName); } } return tagBuilder.ToString(TagRenderMode.SelfClosing); }That works for me (tested just now)
If it ain't simple, it ain't good.
Best Host I had ever (seriously!)
krokonoster
Contributor
3985 Points
1102 Posts
Re: MVC File Upload Validation
Jun 08, 2010 04:16 PM|LINK
I know I should figure it out myself, but would it be possible to overload that "FileBox" helper of mine to be able to call it with say <%: html.FilBox(model=>model.FileName) %> ?
Just asking for incase other's read it.
If it ain't simple, it ain't good.
Best Host I had ever (seriously!)
jedijohn82
Member
2 Points
19 Posts
Re: MVC File Upload Validation
Jun 08, 2010 04:28 PM|LINK
Thanks for the help...The expression version would be like this:
public static String FileBox<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression) { String htmlFieldName = ExpressionHelper.GetExpressionText(expression); return FileBox(html, htmlFieldName); }I had to figure that out for another extension method I created.
krokonoster
Contributor
3985 Points
1102 Posts
Re: MVC File Upload Validation
Jun 08, 2010 04:39 PM|LINK
Thanks for that!
So that solution would work for you?
If it ain't simple, it ain't good.
Best Host I had ever (seriously!)
jedijohn82
Member
2 Points
19 Posts
Re: MVC File Upload Validation
Jun 08, 2010 04:50 PM|LINK
Yes, works like a charm
dcoutts
Member
5 Points
5 Posts
Re: MVC File Upload Validation
Aug 18, 2010 03:50 AM|LINK
Thanks for this great example of an htlmhelper extension
I can see how you obtain the path to a file to upload but I don't see how the file is uploaded. The standard upload file control returns an HttpPostedFileBase object and uploads the file but your control returns just the path to the file. There seems to be something missing in your action method. Can you fill me in?
Thanks
Doug
jedijohn82
Member
2 Points
19 Posts
Re: MVC File Upload Validation
Aug 18, 2010 12:54 PM|LINK
I am not sitting in front of the code where I used this right now, but I the only reason for this helper was to validate that a file existed (i.e. has a filename) and report any error back to the view. I think I still had to get the actual file as you normally would without this helper method.
dcoutts
Member
5 Points
5 Posts
Re: MVC File Upload Validation
Aug 18, 2010 01:53 PM|LINK
Thanks the reply. I agree, the FileBox helper works well to validate that the file exists, particularly with your refinement.
However the only approach I have used previously to upload files is to include a file upload control and work with the HttpPostedFileBase object.SaveAs to actually upload and save the file to a web server directory. There are tons of documentation and examples on this approach on msdn, asp.net, etc. However this approach no longer works once you replace the upload control with the FileBox control.
I have found nothing that demonstrates how to upload a file from a client machine to a web server starting the the fully qualified path on the client machine. If there is a "normal" approach that I am ignorant of, I'd appeciate being pointed in the right direction.
Thanks!
ewdev
Member
4 Points
2 Posts
Re: MVC File Upload Validation
Oct 17, 2010 06:28 PM|LINK
Thanks Krokonoster you really helped me there so I would like to return the favour with my slightly modified version that will work with the new MVC2 <%: %> syntax. I have added the expression version with a modification to the name FileBoxFor rather than FileBox for consistency and also the MvcHtmlString return value:
using System; using System.Collections.Generic; using System.Linq.Expressions; using System.Web.Mvc; using System.Web.Routing; namespace Ewdev.Web { /// <summary> /// Html helper extension for an Input file upload element /// </summary> public static class FileBoxHtmlHelperExtension { /// <summary> /// Returns a file input element by using the specified HTML helper and the name of the form field. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name) { return htmlHelper.FileBox(name, (object)null); } /// <summary> /// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name, object htmlAttributes) { return htmlHelper.FileBox(name, new RouteValueDictionary(htmlAttributes)); } /// <summary> /// Returns a file input element by using the specified HTML helper, the name of the form field, and the HTML attributes. /// </summary> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="name">The name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBox(this HtmlHelper htmlHelper, string name, IDictionary<String, Object> htmlAttributes) { var tagBuilder = new TagBuilder("input"); tagBuilder.MergeAttributes(htmlAttributes); tagBuilder.MergeAttribute("type", "file", true); tagBuilder.MergeAttribute("name", name, true); tagBuilder.GenerateId(name); ModelState modelState; if (htmlHelper.ViewData.ModelState.TryGetValue(name, out modelState)) { if (modelState.Errors.Count > 0) { tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName); } } return MvcHtmlString.Create(tagBuilder.ToString(TagRenderMode.SelfClosing)); } /// <summary> /// Returns a file input element by using the specified HTML helper and the name of the form field as an expression. /// </summary> /// <typeparam name="TModel">The type of the model.</typeparam> /// <typeparam name="TValue">The type of the value.</typeparam> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression) { return htmlHelper.FileBoxFor<TModel, TValue>(expression, (object)null); } /// <summary> /// Returns a file input element by using the specified HTML helper and the name of the form field as an expression. /// </summary> /// <typeparam name="TModel">The type of the model.</typeparam> /// <typeparam name="TValue">The type of the value.</typeparam> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, object htmlAttributes) { return htmlHelper.FileBoxFor<TModel, TValue>(expression, new RouteValueDictionary(htmlAttributes)); } /// <summary> /// Returns a file input element by using the specified HTML helper and the name of the form field as an expression. /// </summary> /// <typeparam name="TModel">The type of the model.</typeparam> /// <typeparam name="TValue">The type of the value.</typeparam> /// <param name="htmlHelper">The HTML helper instance that this method extends.</param> /// <param name="expression">The expression that resolves to the name of the form field and the <see cref="System.Web.Mvc.ViewDataDictionary" /> key that is used to look up the validation errors.</param> /// <param name="htmlAttributes">An object that contains the HTML attributes for the element. The attributes are retrieved through reflection by examining the properties of the object. The object is typically created by using object initializer syntax.</param> /// <returns> /// An input element that has its type attribute set to "file". /// </returns> public static MvcHtmlString FileBoxFor<TModel, TValue>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TValue>> expression, IDictionary<String, Object> htmlAttributes) { var name = ExpressionHelper.GetExpressionText(expression); return htmlHelper.FileBox(name, htmlAttributes); } } }Cheers... Ewdev
asp.net mvc 2.0 Html Helper Extension