3rd lecture for Binary Studio Academy PRO course about .NET Core by Max Goncharuk (.NET developer at Binary Studio) binary-studio.com

1. ASP.NET Core MVC
binary-studio.com

2. Contents
1. Model
2. View
3. Controller

3. Model

4. Model Binding
1. Form values: These are form values that go in the HTTP request
using the POST method. (including jQuery POST requests).
1. Route values: The set of route values provided by routing.
1. Query strings: The query string part of the URI. Model.IsValid

5. Additional types
IFormFile, IEnumerable<IFormFile>: One or more uploaded files that are part of the HTTP request.
CancelationToken: Used to cancel activity in asynchronous controllers.

6. Model Binding Attributes
[BindRequired]: This attribute adds a model state error if binding cannot occur.
[BindNever]: Tells the model binder to never bind to this parameter.
[FromHeader], [FromQuery], [FromRoute], [FromForm]: Use these to specify the exact binding
source you want to apply.
[FromServices]: This attribute uses dependency injection to bind parameters from services.
[FromBody]: Use the configured formatters to bind data from the request body. The formatter is
selected based on content type of the request.
[ModelBinder]: Used to override the default model binder, binding source and name.

7. Input/Output Formatters
Three input formatters:
– JsonInputFormatter – based on JSON.NET
– XmlSerializerInputFormatter – based on XmlSerializer (in the box, but not registered by default)
– XmlDataContractSerializerInputFormatter – based on DataContractSerializer
services.AddMvc()
.AddXmlSerializerFormatters();
services.AddMvc().Configure<MvcOptions>(options =>
{
options.InputFormatters.RemoveAll(formatter =>
formatter.Instance.GetType() == typeof(XmlDataContractSerializerInputFormatter));
});

8. Input/Output Formatters
Six output formatters:
– JsonOutputFormatter – based on JSON.NET
– XmlSerializerOutputFormatter – based on XmlSerializer (in the box, but not registered by default)
– XmlDataContractSerializerOutputFormatter – based on DataContractSerializer
– TextPlainFormatter – used to force a string into a text/plain content type
– HttpNoContentOutputFormatter – used to force 204 status code for null action return
– HttpNotAcceptableOutputFormatter – used to force 406 status code if no appropriate formatter can
be selected to handle the request (in the box, but not registered by default)

9. Model Validation
[CreditCard]: Validates the property has a credit card format.
[Compare]: Validates two properties in a model match.
[EmailAddress]: Validates the property has an email format.
[Phone]: Validates the property has a telephone format.
[Range]: Validates the property value falls within the given range.
[RegularExpression]: Validates that the data matches the specified regular expression.
[Required]: Makes a property required.
[StringLength]: Validates that a string property has at most the given maximum length.
[Url]: Validates the property has a URL format.

10. Model Validation
services.AddMvc(options => options.MaxModelValidationErrors = 50);
TryValidateModel(model);

11. Client Model Validation
<script src="https://ajax.aspnetcdn.com/ajax/jquery.validate/1.14.0/jquery.validate.min.js"></script>
<script src="https://ajax.aspnetcdn.com/ajax/jquery.validation.unobtrusive/3.2.6/jquery.validate.unobtrusive.min.js"></script>
<div class="col-md-10">
<input asp-for="ReleaseDate" class="form-control" />
<span asp-validation-for="ReleaseDate" class="text-danger"></span>
</div>
<input class="form-control" type="datetime"
data-val="true" data-val-required="The ReleaseDate field is required."
id="ReleaseDate" name="ReleaseDate" value="" />
<span class="text-danger field-validation-valid"
data-valmsg-for="ReleaseDate" data-valmsg-replace="true"></span>

12. Remote Client Validation
public class User
{
[Remote(action: "VerifyEmail", controller: "Users")]
public string Email { get; set; }
} [AcceptVerbs("Get", "Post")]
public IActionResult VerifyEmail(string email)
{
if (!_userRepository.VerifyEmail(email))
{
return Json(data: $"Email {email} is already in use.");
}
return Json(data: true);
}

13. Response Data
IActionResult
return View(_myModel);
Json()
return Json(_authorRepository.List());
Content()
return Content("Some content.");
POCOs
[HttpGet("{alias}")]
public Author Get(string alias)
{
return _authorRepository.GetByAlias(alias);
}
Other (Ok(), NotFound(), …)

14. View

15. Tag Helpers
@Html.Label("FirstName", "First Name:", new {@class="caption"})
<label class="caption" asp-for="FirstName">First Name</label>
<label class="caption" for="FirstName">Name First</label>

16. Using Tag Helpers
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers // Add all tag helpers
@removeTabHelper *, Microsoft.AspNetCore.Mvc.TagHelpers // Remove all tag helpers
@tagHelperPrefix th:
<!span asp-validation-for="Email" class="text-danger"></!span> // Disable tag helper
<th:label asp-validation-for="Email" class="text-danger"></th:label> // Use prefix

17. Tag Helpers In Forms
<form asp-controller="Demo" asp-action="Register" method="post">
<!-- Input and Submit elements -->
</form>
<form method="post" action="/Demo/Register">
<!-- Input and Submit elements -->
<input name="__RequestVerificationToken" type="hidden" value="<removed for
brevity>" />
</form>

18. Custom Tag Helper
public class EmailTagHelper : TagHelper
{
private const string EmailDomain = "contoso.com";
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
output.TagName = "a"; // Replaces <email> with <a> tag
var content = await output.GetChildContentAsync();
var target = content.GetContent() + "@" + EmailDomain;
output.Attributes.SetAttribute("href", "mailto:" + target);
output.Content.SetContent(target);
}
}
<email>Support</email> <a href="mailto:Support@contoso.com">Support@contoso.com</a>

19. Dependency Injection
services.AddTransient<StatisticsService>();
@inject StatisticsService StatsService
<h1>Total Items: @await StatsService.GetCount()</h1>

20. View Component
<div>
@await Component.InvokeAsync("NameOfComponent", <anonymous type containing parameters>)
</div>
public IActionResult IndexVC()
{
return ViewComponent("MyList", new { count = 2 });
}

21. View Component
public class MyListViewComponent : ViewComponent
{
public async Task<IViewComponentResult> InvokeAsync(int count)
{
var items = await GetItemsAsync();
return View(items.Take(count));
}
private Task<List<string>> GetItemsAsync()
{
return Task.FromResult(new List<string>{“string1”, “string2”, “string3”});
}
}
Views/Shared/Components/MyList
@model IEnumerable<string>
<h3>Priority Items</h3>
<ul>
@foreach (var item in Model)
{
<li>@item</li>
}
</ul>

22. Controller

23. Routing
Areas
Filters
Error handling
Dependency Injection