Here are my Product and ProductItem classes/models:
public class Product
{
public int ProductId { get; set; }
[Required(ErrorMessage="Enter Name")]
public string Name { get; set; }
public List<ProductItem> productitems { get; set; }
[Required(ErrorMessage="Enter Price")]
public decimal Price { get; set; }
}
public class ProductItem
{
[Required(ErrorMessage="Select Raw Material")]
public int RawMaterial { get; set; }
[Required(ErrorMessage="Enter Quantity")]
public decimal Qty { get; set; }
}
For ProductItem I am adding its fields dynamically with jQuery, as you can see here:
$("#btnAddProductItem").click(function () {
$.getJSON("/rawmaterial/GetRawMaterials", null, function (data) {
var productItem = $("<tr class='productItem' id='productItem-0'><td><select id='rmlist-0' name='productitems[0].RawMaterial'></select><span class='field-validation-valid' data-valmsg-for='productitems[0].RawMaterial' data-valmsg-replace='true'></span></td><td><input type='text' id='rmqty-0' name='productitems[0].Qty'/><span class='field-validation-valid' data-valmsg-for='productitems[0].Qty' data-valmsg-replace='true'></span></td></tr>");
$("#productItem").append(productItem);
$("#rmlist-0").addItems(data);
});
});
Now the validation attributes applied on Name and Price are working fine but not on the fields added dynamically (i.e. "RawMaterial" and "Qty").
Please give me the suggestions how this validation will work ?
Note: For testing purpose I have just added the first object of the List indexed with 0.
There are several ways to accomplish this -
PARTIAL VIEW: Since you are using Server Side data annotation as I see from the class definitions, then it is not a good idea to load dynamically with js. Because you will miss out all the validation that MVC 4 could have created automatically. So, the best solution I would suggest is taking the code that you are adding dynamically to a partial view file and then get the html with ajax call and then populating the HTML.
JS VALIDATION: But, if it is a must that you should use JS, then you have to add all the validation items yourself. To do that you have to do some extra works -
First, inspect the HTML with any developer tools, you will notice that there is a <span> attribute appended after each item to show the error which has a target mentioned. You have to append similar attributes to your elements
With MVC 4 unobtrusive validation, all the validation attributes and rules are added with the target element with data attributes. Each one is based one the validation they stands for. You have you create attributes similar to that.
Finally, after adding all the validation items in JS, reset the form so that it parses the new validations added and work accordingly. The code to parse the validations are here -
var form = $("form") //use more specific selector if you like
form.removeData("validator").removeData("unobtrusiveValidation");
$.validator.unobtrusive.parse(form);
But I would prefer the partial view solution, since it will require least amount of re-work and also gives you option to keep all your validation in one place. You don't have to worry about new validations to be ported to js in future.
Related
Let's say I have the following input tag which utilizes the built-in tag helper:
#model ProductViewModel
<label asp-for="Product.Id"></label>
In my case, this expands into the following:
<label for="Product_Id">Id</label>
I see that asp-for is expecting a ModelExpression:
In tag helper implementations, I often see a property like the following:
public ModelExpression For { get; set; }
It appears that this is automatically populated when the tag helper is used.
Is there a way to instantiate a ModelExpression directly in C#?
I.e. something like this:
var exp = new ModelExpression("Product.Id",...)
I'd like to be able to generate "Product_Id" and "Id" from Product.Id as the input tag helper did.
As far as I know, you can specify that your property is to be set to the name of some property on the View's Model object by declaring your property with the ModelExpression type. This will enable any developer using your property to get IntelliSense support for entering a property name from the Model object. More importantly, your code will be passed the value of that property through the ModelExpression's Model property.
Sample code as below:
[HtmlTargetElement("employee-details")]
public class EmployeeDetailTagHelper : TagHelper
{
[HtmlAttributeName("for-name")]
public ModelExpression EmployeeName { get; set; }
[HtmlAttributeName("for-designation")]
public ModelExpression Designation { get; set; }
public override void Process(TagHelperContext context, TagHelperOutput output)
{
output.TagName = "EmployeeDetails";
output.TagMode = TagMode.StartTagAndEndTag;
var sb = new StringBuilder();
sb.AppendFormat("<span>Name: {0}</span> <br/>", this.EmployeeName.Model);
sb.AppendFormat("<span>Designation: {0}</span>", this.Designation.Model);
output.PreContent.SetHtmlContent(sb.ToString());
}
}
Code in the View page:
#model WebApplication7.Models.EmployeeViewModel
<div class="row">
<employee-details for-name="Name" for-designation="Designation"></employee-details>
</div>
Code in the Model
public class EmployeeViewModel
{
public string Name { get; set; }
public string Designation { get; set; }
}
From above code, you can see that we could custom the attribute name. More detail information about using the ModelExpression, check the following links:
Creating Custom Tag Helpers With ASP.NET Core MVC
Expression names
I'd like to be able to generate "Product_Id" and "Id" from Product.Id
as the input tag helper did.
Besides, do you mean you want to change the Product. Id to Product_Id, in my opinion, I'm not suggesting you change it, because generally we can use "_" as a separator in the property name. So, if we are using Product.Id, it means the Product's Id property, and the Product_Id means there have a Product_Id property.
To answer the question:
Is there a way to instantiate a ModelExpression directly in C#"
Yes you can, through IModelExpressionProvider and its CreateModelExpression method. You can get an instance of this interface through DI.
Now, if you're already in your view and working with tag helpers, Zhi Lv's answer is all you need, as the functionality is built-in and much easier to use. You only need IModelExpressionProvider for when you're in your Razor Page, Controller, or perhaps some custom middleware. Personally, I find this functionality useful for my Ajax handlers that need to return one of my ViewComponents that has a ModelExpression argument (so that I can easily call it from my Pages/Views too.)
To call CreateModelExpression, you'll need a strongly-typed instance of ViewData. In Razor Pages, this is as easy as casting the ViewData property to the strongly-typed instance of your PageModel's type (presuming you don't have a page model hierarchy):
var viewData = (ViewDataDictionary<IndexModel>)ViewData;
If you're using MVC and you're in the controller, that won't exist yet. Best you can do is make your own instance.
var viewData = new ViewDataDictionary<ErrorViewModel>(new EmptyModelMetadataProvider(),
new ModelStateDictionary());
Once you get your strongly-typed ViewData instance, you can obtain your desired ModelExpression like this, just like using a lambda expression in your views:
var myPropertyEx = _modelExpressionProvider.CreateModelExpression(viewData,
m => m.MyProperty);
I'm unable to bind a collection of child-complext objects created dynamically using a partial-view to view-model IEnumerable property.
I have successfully bound objects created dynamically using partial-views to a view-model using a technique I found on this blog https://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx/. I have followed the same technique but I'm unable to bind a collection to a IEnumerable property in a view-model.
[BindRequired]
public class EmployeeViewModel
{
other properties....
public IEnumerable<ContactDetailViewModel> EmployeeContact { get; set; }
}
[BindRequired]
public class ContactDetailViewModel
{
// I use this as my indexer for dynamic elements
public string RecordId { get; set; } = Guid.NewGuid().ToString();
public string Telephone { get; set; }
public string EmailAddress { get; set; }
public string ContactDescription { get; set; }
}
I call into this action-method via ajax to add dynamic contact detail elements and it returns the partial-view as html and it works fine.
[Route("[action]", Name = "BlankEmployeeContactDetail"), HttpGet("AddBlankContactDetail")]
public PartialViewResult AddBlankContactDetail()
{
return PartialView("_ContactInformation", new ContactDetailViewModel());
}
The initial contact detail is added to the main-view using the following, kindly follow this link https://1drv.ms/u/s!AkRSHVUtFlKhuHaxH96Ik4ineATE to download the main view and partial-view cshtml files. It is also noteworthy to mention that model binding fails for all other properties when I include this partial-view but works when I comment it out. I'm baffled and would greatly appreciate any help you can afford me.
<section id="widget-grid" class="">
<div class="row contactContainer">
#{ await Html.RenderPartialAsync("_ContactInformation", new ContactDetailViewModel()); }
</div>
</section>
This is the controller action method I'm trying to bind posted data to:
[Route("[action]"), HttpPost, AllowAnonymous, ValidateAntiForgeryToken]
public IActionResult Register([FromForm] EmployeeViewModel model, [FromQuery] string returnUrl = null)
{
if (ModelState.IsValid)
{
}
return View(model);
}
In order to bind, the input names much follow a particular convention that maps to what you're binding to. While it's unclear from your question, my best guess is that you're trying to ultimately bind to an instance of EmployeeViewModel, which means that your contact information inputs would need names like: EmployeeContact[0].Telephone, but when you pass an instance of ContactDetailViewModel along as the "model" of the partial view, the names will be just Telephone, and worse, these same names will be repeated over and over, i.e. each contact information set of fields you create will all have an input named just Telephone.
Long and short, you need the context of the whole model to generate the correct input names. You have a couple of options.
Since you're retrieving the set of fields via an AJAX request, it would be possible to pass the "prefix" to use along with that request. In other words, you can keep track of an index value, counting how many of these sections you've added, and then send along with the request for a new section something like
prefix: 'EmployeeContact[' + (i + 1) + ']',
Then, in your partial view:
#{ await Html.RenderPartialAsync("_ContactInformation", new ContactDetailViewModel(), new ViewDataDictionary { TemplateInfo = new TemplateInfo { HtmlFieldPrefix = ViewBag.Prefix } } ); }
That's a little hacky, and honestly probably rather prone to error, though. The better option would be to take an entirely different approach. Instead of calling back to get the partial view, define it just once as a template:
<script type="text/html" id="ContactInformationTemplate">
<!-- HTML for contact information inputs -->
</script>
Then, using a library like Vue, React, Angular, etc., you can set up a "foreach" construction tied to a particular JavaScript array which uses this template to render items in that array. Then, adding a new set of inputs is as simple as adding a new item to the array. You will have to do some works to customize the input names based on the index of the item in the array, but all of these client-side frameworks have ways to do that. That would also have the side benefit of not having to make an AJAX request every time you want to add a new section.
I know this is a weird one but bear with me. I need to set a default state/value for form inputs on a portion of my application.
In my "MainController" I pull up a portion (or 'wrapper' of sorts) page and then pull partial views from this main page. Here's a pseudo-code example:
User goes to Main ->
MainController/Index Called
-> User clicks Link A ->
AJAX .load() pulls html from PartialViewA into #partialContainer
-> User clicks Link B ->
AJAX .load pulls html from PartialViewB into #partialContainer
Here's the AJAX call:
$("#mainPanel").load('#Url.Action("GetModule","Settings")' + '?partialName=' + moduleName);
...and the corresponding server-side action that handles it:
public ActionResult GetModule(string partialName)
{
return PartialView(partialName);
}
It works great for me, each of the modules has plenty of form fields on them, all interacting well with one another and server so that isn't my problem. The issue is setting default values from the dbase for the form fields contained in the partial views.
For instance the "General" partial has many checkboxes which will determine how portions of the application display. I want to pull from the database the pre-exisiting boolean value and when the partial gets pulled from GetModule(), have these values defaulted.
I've taken a look around and I'm afraid the way that I am pulling the partial's into the main page may be the issue. I thought I could build the defaults into the constructor like so:
public class GeneralViewModel
{
public GeneralViewModel()
{
var Data = from m in dataContext.Table
where m.UserID == _id
select new
{
m.Data1,
m.Data2,
};
foreach(var setting in Data)
{
Checkbox1 = Convert.ToBoolean(setting.Data1); // Conversion from bool? to bool
Checkbox2 = Convert.ToBoolean(setting.Data2); // Conversion from bool? to bool
}
}
public bool Checkbox1 { get; set; }
public bool Checkbox2 { get; set; }
}
But it would appear the constructor never gets called. That sort of makes sense, except when you consider the fact that my form fields are not only rendering properly, but communicating with the database just fine as well. So the question is, what am I doing wrong? Is it the way I call the Partial's or am I missing something with assigning values to my VM values?
As always, thanks SO!
I think it's better to have different action methods for rendering the partial views, but for your case, i think this solution would work.
Have a Model that contains the other view models
public class ViewModel
{
public ViewModel1 ViewModel1 { get;set;}
public GenereViewModel General {get;set;}
}
Then in your controller you could initialize the viewmodel based on the partial name.
public ActionResult GetModule(string partialName)
{
var model = new ViewModel();
switch (partialName)
{
case "General": model.General = InitializeGeneral();
break;
case "ViewModel1": model.ViewModel1 = InitializeViewModel1(); break;
}
return PartialView(partialName, model);
}
private GeneralViewModel InitializeGeneral()
{
// initalize then return model
}
Can we have a single razor view for both Create and Edit operations?
If yes, how do we achieve this?
I don't recommend it.
This should be a rather long answer, because there's a lot of things involved in the process, request and workflow of a normal MVC GET/POST workflow. I will try to answer your question with the minimum information required and why I do not recommend the use of the same view.
First, why?
You don't have control over the views, which may have over-posting;
No flexibility;
Not reusable views or parts;
Hard to maintain the views (one change in the view must be tested on both actions).
My suggested approach would be to have different actions/views but share common code:
Create both views as normal.
You will have duplicated code, but not all code is the same, for example, you may not want to send an ID on the create action, this is not directly related to your question, but using the same view implies you are also sending the same data, and this is not recommended, especially for over-posting or mass assignment. More info about mass assignment here (an Architectural Approach is what I'm using here).
So let's start from what are you going to receive in your controllers.
In this case I used inheritance but it's not the only strategy.
Binding models
public class UpdateBindingModel : CreateBindingModel {
// since we are not using the same binding model,
// we can have a "real" validation rules on our update binding and view.
[Required]
public int? Id {get;set;}
}
public class CreateBindingModel {
// no id here prevent overposting.
[Required]
public string Name {get;set;}
[Required]
public int? CountryId {get;set;}
}
That will make sure the data you send to your Create and Edit is the minimum needed and nothing else.
Let's then see the View Models that will be sent to the View, for this example I will include a List that will be used to select some value but should not be posted (the list) to the controller, only the selected value.
View models
public class CreateViewModel : CreateBindingModel {
public IEnumerable<SelectListItem> CountryList {get;set;}
}
public class UpdateViewModel : UpdateBindingModel {
public IEnumerable<SelectListItem> CountryList {get;set;}
}
As you can see, this gives you lot of flexibility but still have some duplicated code (the extra information needed on view model for both views) which can be mitigated in several ways (depending the needs/context):
Have an action to retrieve the common data and using #Html.Action("GetCountryList");
Use the same View Model aka CreateUpdateViewModel and discarding extra UpdateBindingModel properties in the view but still posting the corresponding model on POST.
Having your binding models as properties and select one or the other in the specific view. (better use #Html.EditorFor instead of partials so Model Binder will work with no additional change on code)
The controller actions will look like:
Controller
[HttpGet]
public ActionResult Create(){
ViewData.Model = new CreateViewModel();
return View();
}
[HttpPost]
public RedirectToRouteResult Create(CreateBindingModel binding) {
// check valid model state and create data
return RedirectToAction("Index");
}
[HttpGet]
public ActionResult Update(int id) {
var objectToEdit = service.GetObjectToEdit(id);
ViewData.Model = new UpdateViewModel(objectToEdit);
return View();
}
[HttpPost]
public RedirectToRouteResult Update(UpdateBindingModel binding) {
// check valid model state and update data
return RedirectToAction("Index");
}
And your views:
Views
Update.cshtml
<form action="Update">
#Html.HiddenFor(Model.Id);
#Html.Partial("EditFieldsPartial")
<button>delete</button> // no delete button on create.
<button>create new</button> // you can have a create new instead of update.
</form>
Create.cshtml
<form action="Create">
#Html.Partial("EditFieldsPartial")
</form>
Note: code is incomplete and didn't use helpers in most cases for brevity and clarity. Do NOT copy paste :D
Sure you can.
On post, check in your controller whether the primary key has value 0 then Insert, otherwise Update.
View should be the same for Create and Edit.
Just remember to include:
#Html.HiddenFor(model=>model.ID)
In your view
For example:
Model:
public class DescriptionModel
{
[Key]
public int ID { get; set; }
public string Description { get; set; }
}
CreateEdit.cshtml:
#model DescriptionModel
#using (Html.BeginForm("CreateEdit"))
{
#Html.HiddenFor(model=> model.ID)
#Html.EditorFor(model=> model.Description)
<input type="submit" value='Submit' />
}
DescriptionModel controller:
public ActionResult Create()
{
return View("CreateEdit", new DescriptionModel());
}
public ActionResult Edit(int id)
{
return View("CreateEdit", db.DescriptionModels.Find(id));
}
// Submit and add or update database
[HttpPost]
public ActionResult CreateEdit(DescriptionModel model)
{
if (ModelState.IsValid)
{
// No id so we add it to database
if (model.ID <= 0)
{
db.DescriptionModels.Add(model);
}
// Has Id, therefore it's in database so we update
else
{
db.Entry(model).State = EntityState.Modified;
}
db.SaveChanges();
return RedirectToAction("Index");
}
return View(model);
}
A View can definitely be shared for create and edit operations, using the same model. However, i would strongly recommend to think about it twice. In many cases, you will want to have a different view for edit operations(eg. hide some inputs that should not be editible) as well as the model could be slightly different, altought it might share some (or most) values. These difference will lead to some conditions in the view, checking whether you are creating or editing - which could make the code chaotic.
Conclusion: before deciding whether to have a shared view, try to think of how much is the edit screen gonna differ from create screen, then you may decide.
You certainly can, but usually that's something I will try to avoid. If the create and edit actions are virtually the same then you end up duplicating a lot of code in the controller. Usually in this situation I will have only a few fields on my 'Add' controller, and then once the item has been added I redirect the user to the edit page where they can fill in the rest of the information.
I wouldn't recommend that approach but you could have the main form be loaded into both views from a partial
[HttpGet]
public ActionResult myFun(int id = 0)
{
MyClass cls = new MyClass();
if (id == 0)
{
//Insert mode ... no data will be shown to textboxes , when primary key ie. id=0
//Display whole data
}
else
{
//Update mode... if id is not 0 ,data will be shown to textboxes
}
return View(cls);
}
I am using Asp.Net Mvc Web api RC.
I wanted to hide the fields/properties of my model class using custom attribute. Below is my class:
public class Employee
{
public int EmpId { get; set; }
public string Name{ get; set; }
//Wanted to hide this attribute based on custom logic. Like for a certain role, i want to hide the designation
public string Designation{ get; set; }
public string Department{ get; set; }
}
How can we achieve using Data Annotations. I mean i wanted to create a separate attribute to use in this manner:
[HideForRoles(Roles="Admin,Writer")]
public string Designation{ get; set; }
UPDATE :
As i am developing web api. The response is serialized to either XML or Json format depend upon the formatter. So better question would be how not to allow the fields to be serialize while writing to the response.
However one option could be using IgnoreDataMember attribute. Like
[IgnoreDataMember]
public string Designation{ get; set; }
But the above is a compile time declaration where i cannot impose any condition.
Question: How to ignore the field/property while serializing based on some condition at runtime?
Totally missed on the first go-round that you were using Web Api, my apologies.
What you want to do is to create a custom formatter.
There's a good article here on the flow/differences between MVC and Web Api (which I'm getting that you already understand, still some valid points here):
http://lostechies.com/jimmybogard/2012/04/10/asp-net-web-api-mvc-viewmodels-and-formatters/
And here's a sample implementation of a custom formatter:
http://www.tugberkugurlu.com/archive/creating-custom-csvmediatypeformatter-in-asp-net-web-api-for-comma-separated-values-csv-format
Building from that, you would use reflection to read from the attributes, building on the custom ActionFilterAttribute you would have to write, where you evaluate the user's roles and determine which fields should be omitted/included. Here's a sample of an action filter:
https://github.com/MisterJames/MovieFu/blob/master/MovieFu/ActionFilters/UserNameFilter.cs
Hope this helps more.
Cheers.
Your best bet is to return a dynamic object. In this case you can say:
dynamic viewModel = new ExpandoObject();
viewModel.Id = 12;
if(role == "Admin")
{
viewModel.SecureStuff = "Others should not see it";
}
It won't be as straightforward as that, as you'll need to have the fields conditionally rendering in the view. But you can get most of the way there through the attribute.
You will need to make your custom attribute meta-data aware, then check the attribute in your view. A solution is posted here: Can't get Custom Attribute Value in MVC3 HTML Helper.
Cheers.
I have done the authorization checking in the model repository itself. Rather ideal way was to create custom formatters for hiding the certain fields based on some condition.
After getting the list of Employees from db and have them in list, i iterated again and place a NULL to the fields i don't want to display.
The code i have written as:
foreach (var employee in listEmployees)
{
//get all props. of Employees object using reflection
var props = employee .GetType().GetProperties();
//loop through each field to match with the field name to remove/place null
foreach (var propertyInfo in props)
{
var fieldName = propertyInfo.Name;
if (fieldsNamesToRemove .Contains(fieldName))
{
propertyInfo.SetValue(employee , null, null);
}
}
}
here fieldsNamesToRemove is a list that i created dynamically based on roles of current user.
This solution actually placing a NULL for the fields we do not want display. As a result in JSon format the fields are not displaying but in the XML the fields are displaying with syntax like lt; Designation i:nil="true"/ gt;, but manageable as we need to deal mostly with json response.
Thanks Ali and MisterJames for your valuable suggestions