8

I am trying to truncate a long string for display only on my index page. It is shown like so:

<td>
    @Html.DisplayFor(modelItem => item.Description)
</td>

The Description can be 500 characters long but I can't show that much on that grid layout. I'd like to show just the first 25 as they can see all of it on the Details page but I cannot seem to get it to work with out truncating it at the model level.

Something like this would be nice:

@Html.DisplayFor(modelItem => item.Description.Take(25))
@Html.DisplayFor(modelItem => item.Description.Substring(0,25)

EDIT

I'm getting the following exception at Runtime when I try either method.

Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.
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4
  • Have you considered creating an additional model property that performs the substring and using that? Commented May 9, 2014 at 19:48
  • Yeah, that was how I was going to do it if there wasn't a way to work with the Templates and single property. Commented May 9, 2014 at 19:52
  • Your specific problem here is that the expression passed into Html.DisplayFor must reference an actual property, not a specific value. In other words, you can only do @Html.DisplayFor(m => item.Description), not @Html.DisplayFor(m => item.Description.Substring(0, 25)). You don't need to use Html.DisplayFor for this, though, so you can just write @item.Description.Substring(0, 25). However, bear in mind @48klocs's comment to Nathan A's answer. Commented May 9, 2014 at 20:03
  • 1
    Note that Take() returns a IEnumerable<char>, not a string. Substring() is more suited for this. Commented May 9, 2014 at 20:05

7 Answers 7

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29

Don't use the html helper. Just do this:

@item.Description.Substring(0, Math.Min(item.Description.Length, 25));

I'm assuming you are in some loop where item is the current element.

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3 Comments

That will throw an ArgumentOutOfRangeException if the string isn't longer than 25 characters.
@NathanA , this works great, but can you provide option 2 to show dots at the end like this mydescription ..... , i tried this and gives error when parsed, do you have any idea?
@NathanA thank you so much. I was struggling with this since 2 hours finally got the solution
7

You could do this with an extension method.

public static string Truncate(this string source, int length)
{
    if (source.Length > length)
    {
        source = source.Substring(0, length);
    }

    return source;
}

Then in your view:

@item.Description.Truncate(25)
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3 Comments

That still won't work. DisplayFor only accepts expressions that result in a value (specifically what's listed in the error), not method calls. That's what is generating the Templates error.
@NathanA you're probably right. I didn't check what the call for DisplayFor vs. Display was. I think a named Display element should work, but I'm just guessing there.
That looks better. Good general application.
4

you could either truncate the data before it gets to the View, or use this Razor:

@{
    var shortDescript = String.Concat(modelItem.Take(25));
}
@Html.DisplayFor(modelItem => shortDescript)
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2 Comments

While that may work, why would you use DisplayFor at all then? Any benefit you would get using it on a member of your data model is lost doing it this way.
Assuming the type did not change (string to string), you can still make use of the same display template. See stackoverflow.com/a/6365658/1445356
1

You might consider creating a special model property for such instances where you need this: 

public class MyModel
{
    public string MyDescription {get; set;}
    public string MyShortDescription {
        get 
        {
              return Truncate(MyDescription, 25);
        }
}

private string Truncate(string, howMany)
{
   // Code to perform the substring here
}

@Html.DisplayFor(modelItem => item.MyShortDescription);
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1

Try this if you want to use the HTML helpers. Say you want to get part of a string before the first space .IndexOf(' ') (or you can just use a predefined index 25 like u said):

@Html.DisplayFor(modelItem => item.Description).ToString().Substring(0,item.Description.IndexOf(' '))
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1

The HTML helper for ASP Net Core 3 MVC.

public static HtmlString Truncate(this IHtmlHelper helper, string text, int maxLength = 100)
{
    if (text == null) return new HtmlString("");

    if (text.Length > maxLength)
    {
        text = text.Substring(0, maxLength) + "...";
    }
    return new HtmlString($"{text}");
}

Use in cshtml file

@Html.Truncate(item.Description)

Or you can use param

@Html.Truncate(item.MusicUrl, 50)
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0

Try an extension

public static string TruncateMiddle(this string value, int lengthExpected, string separator = "...")
    {
        if (value.Length <= lengthExpected) return value;

        decimal sepLen = separator.Length;
        decimal charsToShow = lengthExpected - sepLen;
        decimal frontChars = Math.Ceiling(charsToShow / 2);
        decimal backChars = Math.Floor(charsToShow / 2);

        return value.Substring(0, (int)frontChars) + separator + value.Substring(value.Length - (int)backChars);            
    }

Use

MyLongString.TruncateMiddle(50)

Return something like this: Lorem ipsum dolor sit ame...onsectetur cras amet.

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