- Razor supports C# - It uses the @ symbol to transition from HTML to C#. - When an @ symbol is followed by a Razor reserved keyword, it transitions into Razor-specific markup. Otherwise, it transitions into plain HTML. - To escape an @ symbol in Razor markup, use a second @ symbol:


     < p>@@Username< /p>

-Implicit Razor expressions Implicit Razor expressions start with @ followed by C# code:


    < p>@DateTime.Now< /p>
    < p>@DateTime.IsLeapYear(2016)< /p>

- Implicit expressions cannot contain C# generics, as the characters inside the brackets (< >) are interpreted as an HTML tag. -Explicit Razor expressions Explicit Razor expressions consist of an @ symbol with balanced parenthesis. - Example 1:


    < p>Last week this time: @(DateTime.Now - TimeSpan.FromDays(7))< /p>

- Exaample 2:


    @{
      var joe = new Person("Joe", 33);
    }

    < p>Age@(joe.Age)< /p>

-Explicit expressions can be used to render output from generic methods in .cshtml files.


      < p >@(GenericMethod< int >())< /p >

-Expression encoding

@("< span >Hello World< /span >")   // Encodes to : <span>Hello World</span>

- HtmlHelper.Raw output isn't encoded but rendered as HTML markup.


@Html.Raw("< span >Hello World< /span >")  //< span >Hello World< /span >

-Razor code blocks Razor code blocks start with @ and are enclosed by {}.


  @{
    var quote = "The future depends on what you do today. - Mahatma Gandhi";
}
< p>@quote< /p>
// renders: < p>The future depends on what you do today. - Mahatma Gandhi< /p>

- In code blocks, declare local functions with markup to serve as templating methods:


  @{
    void RenderName(string name)
    {
        Name: @name
    }

    RenderName("Mahatma Gandhi");
    RenderName("Martin Luther King, Jr.");
}

// Renders: 
< p>Name: < strong>Mahatma Gandhi< /strong>< /p>
< p>Name: < strong>Martin Luther King, Jr.< /strong>< /p>

-Implicit transitions The default language in a code block is C#, but the Razor Page can transition back to HTML:


  @{
    var inCSharp = true;
    Now in HTML, was in C# @inCSharp
}

-Explicit delimited transition To define a subsection of a code block that should render HTML, surround the characters for rendering with the Razor < text> tag:


@for (var i = 0; i < people.Length; i++)
{
    var person = people[i];
    Name: @person.Name
}

-Explicit line transition To render the rest of an entire line as HTML inside a code block, use @: syntax:


@for (var i = 0; i < people.Length; i++)
{
    var person = people[i];
    @:Name: @person.Name
}

Conditionals @if, else if, else, and @switch


    @if (value % 2 == 0)
    {
        The value was even.
    }
    else if (value >= 1337)
    {
        The value is large.
    }
    else
    {
        The value is odd and small.
    }

    @switch (value)
    {
        case 1:
            The value is 1!
            break;
        case 1337:
            Your number is 1337!
            break;
        default:
            Your number wasn't 1 or 1337.
            break;
    }

Looping @for, @foreach, @while, and @do while


    @{
        var people = new Person[]
        {
              new Person("Weston", 33),
              new Person("Johnathon", 41),
              ...
        };

        @for (var i = 0; i < people.Length; i++)
        {
            var person = people[i];
            Name: @person.Name
            Age: @person.Age
        }

        @foreach (var person in people)
        {
            Name: @person.Name
            Age: @person.Age
        }

        @{ var i = 0; }
        @while (i < people.Length)
        {
            var person = people[i];
            Name: @person.Name
            Age: @person.Age

            i++;
        }

        @{ var i = 0; }
        @do
        {
            var person = people[i];
            Name: @person.Name
            Age: @person.Age

            i++;
        } while (i < people.Length);
    }

@using In Razor,like C#, a using statement is used to ensure an object is disposed.


  @using (Html.BeginForm())
{
    < div>
        Email: < input type="email" id="Email" value="">
        < button>Register< /button>
    < /div>
}

@try, catch, finally


  @try
  {
      throw new InvalidOperationException("You did something invalid.");
  }
  catch (Exception ex)
  {
      The exception message: @ex.Message
  }
  finally
  {
      The finally statement.
  }

@inherits @inherits TypeNameOfClassToInheritFrom @inject The @inject directive enables the Razor Page to inject a service from the service container into a view.

References

tips

razor