Razor Syntax

A Razor content page acts as a template for generating HTML. The typical content page includes static HTML, tag helpers that emit HTML dynamically, and C# code. The C# code is embedded within the static content and tag helpers according to a set of rules, or syntax.

All code blocks must appear within @{ ... } brackets. As soon as you type @, you are assumed to have started writing C'#code. Everything that follows is assumed to be code, unless you tell Razor otherwise:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        ...
   }
}

The value of variables are rendered into HTML by prefixing them with the @ sign:

The time is @DateTime.Now

If you want to render the variable number within the loop from the above example, you have to prefix it with an @ sign:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
           @number
    }
}

If you want to render the result of a single line expression, you use the @( ... ) syntax:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        @(number * 10)
    }
}

If you want to include static content that includes a @ sign (e.g. an email address), you need to tell Razor that this instance of the @ sign doesn't indicate code. You do that by doubling or escaping the @ sign:

For support, contact support@@domain.com

If you want to mix inline variables with items to be rendered literally (verbatim strings) within a code block, there are three ways to tell Razor where the code pauses and the literal text or markup begins. The first, if the additional item is text only, is to prefix the text with @: before the first instance of text in the line:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        @(number * 10)@: 
    }
}

You only need to use the @: operator once per line:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        @(number * 10)@: * 10 = @(number * 10)
    }
}

Razor also looks for html tags. If it sees one, it jumps out of code and will only jump back into code when it sees a matching closing tag:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        <span>@(number * 10)&nbsp;</span>
    }
}

Razor can recognise self-closing tags:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        @(number * 10)<br />
    }
}

If you do not want to render html tags, you can use the <text> tag to tell Razor where code ends and begins again. The <text> tag is not rendered to the browser:

@{
    var numbers = Enumerable.Range(1, 10); //Get numbers from 1 - 10
    foreach(var number in numbers){
        <text>@(number * 10) * 10 = @(number * 10)&nbsp;</text>
    }
}

Comments within a code block can denoted by two forward slashes //, as can be seen in all the preceding examples. Alternatively, you can use /*...*/ or @*...*@. If you want to put a server side comment outside of a code block, precede the line @*

@{
    /*Get numbers from 1 - 10*/
    //Get numbers  between 1 - 10
    @*Get numbers between 1 - 10*@
    var numbers = Enumerable.Range(1, 10); 
    foreach(var number in numbers){
        @number
    }
}

The following example illustrates two things - the first is commenting outside of code blocks using the @*...*@ syntax. The second is that iteration and selection statement keywords (if, for, foreach, switch, while etc) do not need curly braces before them. A simple @ sign will do. The same is true for try... catch, if you want to use that particular construct inline.

@* Get numbers between 1 - 10 *@

@{ var numbers = Enumerable.Range(1, 10); }

@foreach(var number in numbers){
    @number
}

@for(var i = 0; i < numbers.Count(); i++){
    @numbers.ElementAt(i)
}

@if(numbers.Count() == 10){
    @:10 Numbers - Good!   
}

@{var condition = 1; var message = "";}

@switch(condition){
    case 1:
        message = "Case 1";
        break;
    case 2:
        message = "Case 2";
        break;
    case 3:
        message = "Case 3";
        break;
    default:
        message = "Default Case";
        break;
}

@message
Last updated: 20/03/2018 09:39:16

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