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C# net core 6 How to convert a partial view to json / html string

I want to refresh a partial view (main) with a single call to reduce the traffic on the network. That one partial view have multiple more partial view (child) inside it. However, I cannot use standard mainpartialview.html(response) approach because one of the child partial view have conflict with the script file. I want to proceed with using JSON however the value inside the model for languageForm and translationForm is empty.The suggestion that I found is require me to use microsoft.aspnetcore.mvc.viewfeatures however it not for Net 6.
Old approach
retun PartialView("~/Views/Facility/Translation/_PanelMain.cshtml", result);
New approach
return Json(new
{
languageForm = PartialView("~/Views/Facility/Translation/_Form_Language.cshtml", result.record),
translationForm = PartialView("~/Views/Facility/Translation/_PanelSub.cshtml", result.subRecord),
translationViewModel = result.subRecord
});
From the accepted answer, below is the full solution
C# Controller
[HttpGet]
public async Task<ActionResult> GetLanguageRecord(long? languageID)
{
LoadViewBag();
var loadOptions = GetDefaultDataSourceLoadOptions();
var languageList = _languageService.GetGridViewList(GetMembershipID(), null, loadOptions);
var translationList = _translationService.GetGridViewList(GetMembershipID(), languageID, loadOptions);
var result = PopulateViewModel(languageID ?? 0, 0, languageList, translationList, loadOptions);
result.record.TransactionTypeID = SubmissionType.Edit;
var services = HttpContext.RequestServices;
var options = services.GetRequiredService<IOptions<MvcViewOptions>>().Value;
var executor = (PartialViewResultExecutor)services.GetRequiredService<IActionResultExecutor<PartialViewResult>>();
return Json(new
{
languageForm = await Render(
options,
ControllerContext,
PartialView("~/Views/Facility/Translation/_Form_Language.cshtml", result.record),
executor),
translationForm = await Render(
options,
ControllerContext,
PartialView("~/Views/Facility/Translation/_PanelSub.cshtml", result.subRecord),
executor),
translationViewModel = result.subRecord
});
}
Javascript
function grdMain_Language_selection_changed(selectedItems) {
var data = selectedItems.selectedRowsData[0];
if (data) {
$.ajax({
type: "GET",
url: "Translation/GetLanguageRecord",
data: { languageID: data.ID },
cache: false,
success: function (response) {
document.getElementById("_EntryForm_Language").innerHTML = response.languageForm;
document.getElementById("_SubPanel").innerHTML = response.translationForm;
$('#_subPanel_body').collapse('hide');
$('#_mainPanel_body').collapse('show');
myData_Translation = response.translationViewModel.recordList;
myTotalCount_Translation = response.translationViewModel.recordTotal;
let gvElement_Translation = document.getElementById("grdSub_Translation");
let gvInstance_Translation = DevExpress.ui.dxDataGrid.getInstance(gvElement_Translation);
gvInstance_Translation.refresh();
}
});
$(window).scrollTop(0);
}
}

After a quick look through the internal implementation for return PartialView("viewname");. I think this is the minimum you need to render a partial view into a string;
public async Task<string> Render(MvcViewOptions options, ActionContext context, PartialViewResult result, PartialViewResultExecutor executor)
{
var viewEngineResult = executor.FindView(context, result);
viewEngineResult.EnsureSuccessful(originalLocations: null);
var view = viewEngineResult.View;
using (view as IDisposable)
{
using var writer = new StringWriter();
var viewContext = new ViewContext(
context,
view,
result.ViewData,
result.TempData,
writer,
options.HtmlHelperOptions);
await view.RenderAsync(viewContext);
await writer.FlushAsync();
return writer.ToString();
}
}
Which you would use like;
var services = HttpContext.RequestServices;
var options = services.GetRequiredService<IOptions<MvcViewOptions>>().Value;
var executor = (PartialViewResultExecutor)services.GetRequiredService<IActionResultExecutor<PartialViewResult>>();
return Json(new {
languageForm = await Render(
options,
ControllerContext,
PartialView("~/Views/Facility/Translation/_Form_Language.cshtml", result.record),
executor),
...
});
With a bit more effort, you could probably use a Utf8JsonWriter to render each view html directly to the response body without any caching.

C# MVC 5 - How to create email templates using .cshtml?

In C# MVC 5, is there any built in way to create email templates from .cshtml files?
I'd like to compile the .cshtml based on the model we pass in, thus creating a raw .html string.
It appears the compilation is not callable in C# MVC. We need the raw HTML output because we're trying to send emails.
If possible, avoid 3rd party libraries in the answers - trying to stick within vanilla C#.
What I've tried
Here-strings could be a possible solution, but they could get messy and hard to read. They also wouldn't show the same IDE linting as having a .cshtml file.

Absolutely you can do this yourself.
Options 1: use _partialViews with a dynamic model and renderpartial to or the option to render to HTMLstring #Html.Partial(_PartialView,(ModelClass)View.Data)
Option 2: build your template based on the user/tenant/selection on the server side.
This example is getting ready to send out a confirmation on registration, and inside the comments you can see where you can switch/load different HTML temaplates
// POST: /Account/Register
[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Register(RegisterViewModel model, string returnUrl = null)
{
ViewData["ReturnUrl"] = returnUrl;
if (ModelState.IsValid)
{
var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
var result = await _userManager.CreateAsync(user, model.Password);
// var user = await _userManager.FindByEmailAsync(model.Email);
if (result.Succeeded)
{
// Send an email with this link
var code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
var callbackUrl = Url.Action(nameof(ConfirmEmail), "Account", new { userId = user.Id, code = code }, protocol: HttpContext.Request.Scheme);
//Email from Email Template
string Message = "Please confirm your account by clicking here";
// string body;
var webRoot = _env.WebRootPath; //get wwwroot Folder
//Get TemplateFile located at wwwroot/Templates/EmailTemplate/Register_EmailTemplate.html
var pathToFile = _env.WebRootPath
+ Path.DirectorySeparatorChar.ToString()
+ "Templates"
+ Path.DirectorySeparatorChar.ToString()
+ "EmailTemplate"
+ Path.DirectorySeparatorChar.ToString()
+ "Confirm_Account_Registration.html";
var subject = "Confirm Account Registration";
var builder = new BodyBuilder();
using (StreamReader SourceReader = System.IO.File.OpenText(pathToFile))
{
builder.HtmlBody = SourceReader.ReadToEnd();
}
//{0} : Subject
//{1} : DateTime
//{2} : Email
//{3} : Username
//{4} : Password
//{5} : Message
//{6} : callbackURL
string messageBody = string.Format(builder.HtmlBody,
subject,
String.Format("{0:dddd, d MMMM yyyy}", DateTime.Now),
model.Email,
model.Email,
model.Password,
Message,
callbackUrl
);
await _emailSender.SendEmailAsync(model.Email, subject, messageBody);
ViewData["Message"] = $"Please confirm your account by clicking this link: <a href='{callbackUrl}' class='btn btn-primary'>Confirmation Link</a>";
ViewData["MessageValue"] = "1";
_logger.LogInformation(3, "User created a new account with password.");
return RedirectToLocal(returnUrl);
}
ViewData["Message"] = $"Error creating user. Please try again later";
ViewData["MessageValue"] = "0";
AddErrors(result);
}
// If we got this far, something failed, redisplay form
return View(model);
}

This is a method I use to strongly type a model to a .cshtml and get Razor to render html as a variable I can use with email bodies.
public string ProcessView<TModel>(string viewName, object model, ControllerContext controllerContext, ViewDataDictionary viewData, TempDataDictionary tempData)
{
Check.NullOrEmpty(viewName, "viewName", "View name is required.");
Check.Null(viewData, "viewData", "It might be nothing, but view data was null and the original .net code has a special case for it.");
var dictionary = new ViewDataDictionary(viewData)
{
Model = model,
};
using (var writer = new System.IO.StringWriter())
{
var hostView = new RazorView(controllerContext, "nothing", String.Empty, false, Enumerable.Empty<string>());
var tempContext = new ViewContext(controllerContext, hostView, viewData, tempData, writer);
var view = FindPartialView(tempContext, viewName);
var viewContext = new ViewContext(controllerContext, view, dictionary, tempData, writer);
view.Render(viewContext, writer);
return writer.ToString();
}
}
private static IView FindPartialView(ViewContext viewContext, string partialViewName)
{
var viewEngineCollection = ViewEngines.Engines;
ViewEngineResult result = viewEngineCollection.FindPartialView(viewContext, partialViewName);
if (result.View != null)
{
return result.View;
}
StringBuilder builder = new StringBuilder();
foreach (string str in result.SearchedLocations)
{
builder.AppendLine();
builder.Append(str);
}
throw new InvalidOperationException("Could not find view named:" + partialViewName + " The following locations where checked: " + builder);
}

My email template seems to be null. - Gives errors on RenderToStringAsync

Each time, like trying to send an email, I will not be sent, but it says:
An unhandled exception occurred while processing the request.
ArgumentNullException: Value cannot be null. Parameter name:
Templates/NewPassword does not match any available view
This is what it looks like when I refer to the file.
That's how I've tried to look here.Github - Paris Plyzos
Also code here:
var resultMail = await _viewRenderService.RenderToStringAsync("Templates/NewPassword", viewModel); //ERROR HERE!
var client = new SendGridClient(m.azureName());
var from = new EmailAddress(m.mailFrom(), m.nameFrom());
var to = new EmailAddress(mail, UserValue.Navn);
var plainTextContent = Regex.Replace(resultMail, "<[^>]*>", "");
var msg = MailHelper.CreateSingleEmail(from, to, title, plainTextContent: plainTextContent,
htmlContent: null);
var resulta = client.SendEmailAsync(msg);
return RedirectToAction("UserPassword");
RenderToStringAsync code here - I've written an error where the error goes wrong here.
public async Task<string> RenderToStringAsync(string viewName, object model)
{
var httpContext = new DefaultHttpContext { RequestServices = _serviceProvider };
var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
using (var sw = new StringWriter())
{
var viewResult = _razorViewEngine.FindView(actionContext, viewName, false);//ERROR HERE
if (viewResult.View == null)
{
throw new ArgumentNullException($"{viewName} does not match any available view");
}
var viewDictionary = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary())
{
Model = model
};
var viewContext = new ViewContext(actionContext, viewResult.View, viewDictionary, new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
sw,
new HtmlHelperOptions()
);
await viewResult.View.RenderAsync(viewContext);
return sw.ToString();
}
}

How is your IViewRenderService.RenderToStringAsync() implementation finding views? If you are using IRazorViewEngine, the ViewName has to be fully qualified including file extension ex "~/Views/Home/Index.cshtml"

html.hiddenfor error when rendering view outside controller as string

I need server side page render (without request) outside controller(I want to render view outside controller).
To do that, i need a fake HttpRequest to create ControllerContext so i can render view with razor.Render() and return
stringWriter.ToString() to client using signalr hub.
So i used this code to render partialview as string;
public class FakeController : Controller { }
HttpRequest httpRequest = new HttpRequest("", new UriBuilder("http", "localhost", 10654, "/" + "SomeController/SomeAction").Uri.ToString(), "");
var routeData = new RouteData();
routeData.Values.Add("Controller", "SomeController");
routeData.Values.Add("Action", "SomeAction");
StringWriter stringWriter = new StringWriter();
HttpResponse httpResponse = new HttpResponse(stringWriter);
HttpContext httpContextMock = new HttpContext(httpRequest, httpResponse);
var _contextWrapper = new HttpContextWrapper(httpContextMock);
var controllerContext = new ControllerContext(new RequestContext(_contextWrapper , routeData), new FakeController());
string filePath = "~/Areas/Site/Views/Shared/SomePartialView.cshtml";
var razor = new RazorView(controllerContext, filePath, null, false, null);
razor.Render(new ViewContext(controllerContext, razor, new ViewDataDictionary(model), new TempDataDictionary(), stringWriter), stringWriter);
return stringWriter.ToString();
Here when code tries to render #Html.HiddenFor(m => m.property)
I get error;
source : System.Web.WebPages
error : Object reference not set to an instance of an object
But the weird thing is that i can get #Model.property value(i mean it is not null) and also the other model properties(And it seems that only #Html.HiddenFor or #Html.Hidden is the problem).

How to convert html string to jpg image in asp.net mvc 4

I am trying to convert html string from my view to image. I am able to get my view as string but not able to convert it in image(base64string or byte array) to return it back. This is my code
/* Getting label design info */
LabelDesigner ObjModel = GetLabelDesignObject("Drug_Label");
/* Taking view's HTML */
string HTML = RenderRazorViewToString("~/Views/Folder/DrugLabel.cshtml", ObjModel);
.............
.............
.............
.............
public string RenderRazorViewToString(string ViewName, object Model)
{
string ReturnVal = string.Empty;
try
{
ViewData.Model = Model;
using (var sw = new System.IO.StringWriter())
{
var viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, ViewName);
var viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
viewResult.View.Render(viewContext, sw);
viewResult.ViewEngine.ReleaseView(ControllerContext, viewResult.View);
return sw.GetStringBuilder().ToString();
}
}
catch (Exception ex)
{
/* Catch Exception Here */
log.Error("Error in Controller.cs, RenderRazorViewToString function: " + ex.Message);
}
return ReturnVal;
}
Here I am able to get HTML of view but how to convert that HTML string to jpg image?