问题
I want to write a Edit.cshtml file for an entity with many properties to edit, so I have to write the following codes many times:
<div class="form-group">
<label asp-for="Email" class="col-md-2 control-label"></label>
<div class="col-md-10">
<input asp-for="Email" class="form-control" />
<span asp-validation-for="Email" class="text-danger"></span>
</div>
</div>
Actually, there are many entities so that I have to write many Edit.cshtml files. I want to make some simplifications
I want to select some properties of the entity in the controller and use loop to show the properties in the view. For example: In the controller file:
public IActionResult Edit(string id)
{
var model = GetModel(id);
var propertyNames= new List<string>()
{
"Name",
"Email"
// add some other property names of the entity
};
ViewData["PropertyList"] = propertyNames;
return View(model);
}
In the view file:
@{
var propertyNames = (List<string>)ViewData["PropertyList"];
foreach (string item in propertyNames)
{
<div class="form-group">
<label asp-for="@(item)" class="col-md-2 control-label"></label>
<div class="col-md-3">
<input asp-for="@(item)" class="form-control" />
<span asp-validation-for="@(item)" class="text-danger"></span>
</div>
</div>
}
}
but it cannot work, since it generates wrong codes. It seems that I cannot pass a string value for "asp-for" tag helper.
For example, if I change the code of top to this:
@{
string e = "Email";
<div class="form-group">
<label asp-for="@e" class="col-md-2 control-label"></label>
<div class="col-md-10">
<input asp-for="@e" class="form-control" />
<span asp-validation-for="@e" class="text-danger"></span>
</div>
</div>
}
The code above will generate this:
<div class="form-group">
<label class="col-md-2 control-label" for="e">e</label>
<div class="col-md-10">
<input class="form-control" type="text" id="e" name="e" value="Email" />
<span class="text-danger field-validation-valid" data-valmsg-for="e" data-valmsg-replace="true"></span>
</div>
</div>
The expected code is:
<div class="form-group">
<label class="col-md-2 control-label" for="Email">Email</label>
<div class="col-md-10">
<input class="form-control" type="email" data-val="true" data-val-email="Email 字段不是有效的电子邮件地址。" data-val-required="Email 字段是必需的。" id="Email" name="Email" value="" />
<span class="text-danger field-validation-valid" data-valmsg-for="Email" data-valmsg-replace="true"></span>
</div>
</div>
How should I do?
Is it possible in razor?
回答1:
Ok, I managed to get this working. DISCLAIMER: It is super hacky and I have no idea if I've done it in the best way possible. All I know is that it does what you want and it might point you in the right direction.
Firstly, I created a model:
using System.ComponentModel.DataAnnotations;
namespace WebApplication1.Models
{
public class TestModel
{
[Required]
public string Name { get; set; }
[Required]
[EmailAddress]
[Display(Name = "Email Address")]
public string Email { get; set; }
}
}
Then, I made a custom tag helper. This is the horrible bit where the "magic" happens. Specifically the first section of the Process method...
using Microsoft.AspNet.Mvc.Rendering;
using Microsoft.AspNet.Mvc.ViewFeatures;
using Microsoft.AspNet.Razor.TagHelpers;
using System.Linq;
namespace WebApplication1.TagHelpers
{
[HtmlTargetElement("edit")]
public class EditTagHelper : TagHelper
{
[HtmlAttributeName("asp-for")]
public ModelExpression aspFor { get; set; }
[ViewContext]
[HtmlAttributeNotBound]
public ViewContext ViewContext { get; set; }
protected IHtmlGenerator _generator { get; set; }
public EditTagHelper(IHtmlGenerator generator)
{
_generator = generator;
}
public override void Process(TagHelperContext context, TagHelperOutput output)
{
var propName = aspFor.ModelExplorer.Model.ToString();
var modelExProp = aspFor.ModelExplorer.Container.Properties.Single(x => x.Metadata.PropertyName.Equals(propName));
var propValue = modelExProp.Model;
var propEditFormatString = modelExProp.Metadata.EditFormatString;
var label = _generator.GenerateLabel(ViewContext, aspFor.ModelExplorer,
propName, propName, new { @class = "col-md-2 control-label", @type = "email" });
var input = _generator.GenerateTextBox(ViewContext, aspFor.ModelExplorer,
propName, propValue, propEditFormatString, new { @class = "form-control" });
var validation = _generator.GenerateValidationMessage(ViewContext, aspFor.ModelExplorer,
propName, string.Empty, string.Empty, new { @class = "text-danger" });
var inputParent = new TagBuilder("div");
inputParent.AddCssClass("col-md-10");
inputParent.InnerHtml.Append(input);
inputParent.InnerHtml.Append(validation);
var parent = new TagBuilder("div");
parent.AddCssClass("form-group");
parent.InnerHtml.Append(label);
parent.InnerHtml.Append(inputParent);
output.Content.SetContent(parent);
base.Process(context, output);
}
}
}
NB: To make the custom TagHelper work, you need to add a line into the _ViewImports.cshtml file, like this (replace WebApplication1 with your namespace):
@addTagHelper "*, WebApplication1"
I changed my action to this, to sort of match yours (maybe you can use reflection to get your model property names here?):
public IActionResult Index()
{
var propertyNames = new List<string>()
{
"Name",
"Email"
};
ViewData["PropertyList"] = propertyNames;
var m = new TestModel()
{
Name = "huoshan12345",
Email = "test@test.net"
};
return View(m);
}
Then finally, in the view, you can do something like this:
<div class="row">
@using (Html.BeginForm())
{
var propertyNames = (List<string>)ViewData["PropertyList"];
foreach (string item in propertyNames)
{
<edit asp-for="@item"></edit>
}
<input type="submit" value="Submit" />
}
</div>
回答2:
Yes, it is possible to write it with razor.
think this will help you. If you don't put the "type" attribute it will generate it with type='text'. You can also hard code your data-val attributes, but it is not recommended just replace the '-' with '_' Ex: @data_val_email
<div class="form-group">
@Html.LabelFor(x=>x.Email)
<div class="col-md-10">
@Html.TextBoxFor(x => x.Email, new { @class = "form-control", @type = "email" })
@Html.ValidateFor(x=>x.Email)
</div>
</div>
回答3:
Here's a related technique. I extended the tag helper to inject the required HTML into the page. This works a bit like the ASP.NET MVC EditorTemplate.
Here's the custom tag helper that injects a special partial view
public class MyFormGroupTagHelper : PartialTagHelper
{
public MyFormGroupTagHelper(ICompositeViewEngine viewEngine, IViewBufferScope viewBufferScope) : base(viewEngine, viewBufferScope)
{ }
public ModelExpression Property { get; set; }
public string LabelText { get; set; } = null;
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
this.For = Property;
this.Name = "_FormGroup";
// Have to use Viewdata to pass information to the partial view, because the model is the single property of the entity that will be posted back to the controller
this.ViewData["TH_LabelText"] = LabelText;
this.ViewData["TH_DataTypeName"] = Property.Metadata.DataTypeName;
await base.ProcessAsync(context, output);
}
}
Here's the partial view _FormGroup.cshtml. This generates the markup for a single field on a form with the Bootstrap styles. It also attaches the "datepicker" class to the input tag if the field is a date. Notice how asp-for is populated with @Model so this same view can be bound to any property on any entity model
@model object
@{
string LabelText = (string)@ViewData["TH_LabelText"];
string DataTypeName = (string) ViewData["TH_DataTypeName"];
bool IsDate = (DataTypeName == "Date");
}
<div class="form-group row">
@if (LabelText != null)
{
<label asp-for="@Model" class="control-label col-md-4">@LabelText</label>
}
<div class="col-md-8">
<input asp-for="@Model" class="form-control @( IsDate ? "datepicker" : "")" />
<span asp-validation-for="@Model" class="text-danger"></span>
</div>
</div>
Now in the Create or Edit view, where the model is the business entity, you can create the code to edit a single property on the entity like this.
<my-form-group label-text="Result date" property="ResultDate" view-data="ViewData" ></my-form-group>
In this case the model is a class with a field called ResultDate defined like this:
[DataType(DataType.Date)]
public DateTime? ResultDate { get; set; }
Note that you must set the view-data attribute to pass the ViewData object into tag helper. It uses ViewData to pass information on to the partial view. This isn't ideal but I couldn't think of any other way to pass information through to the partial view. I prefixed the keys with "TH_" to prevent the tag helper overwriting any other values in Viewdata.
来源：https://stackoverflow.com/questions/34282640/how-can-i-pass-string-value-for-asp-for-in-asp-net-5