Need to truncate Razor HTML DisplayFor Helper

Question

I am trying to truncate a text field that is sometimes extremely large or at other times it is null from the database i.e

@Html.DisplayFor(modelItem => item.MainBiography)

and replace with three dots at the end.

I have tried the substring function but keep getting errors.

Any pointers, thanks!

Update:

The ... is not hugely important so I tried using

 @Html.DisplayFor(modelItem => item.MainBiography.Substring(0,10)) 

and get the following error codes:

System.InvalidOperationException was unhandled by user code HResult=-2146233079 Message=Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions. Source=System.Web.Mvc –

Answer 1

Try using Html.Display instead of DisplayFor like this:

 @Html.Display(item.MainBiography.Substring(0, 10), null, "MainBiography")

By the way your both lambda statements are invalid.Parameter names should be the same.

Not like this:

@Html.DisplayFor(modelItem => item.MainBiography)

It should be:

@Html.DisplayFor(modelItem => modelItem.MainBiography)

Or:

@Html.DisplayFor(item => item.MainBiography)

Answer 2

You may write a string extension method and call that on your model property (of string type). You can pass the limit for your substring operation.

public static class StringExtensions
{
    public static string SubStringTo(this string thatString, int limit)
    {
        if (!String.IsNullOrEmpty(thatString))
        {
            if (thatString.Length > limit)
            {
                return thatString.Substring(0, limit);
            }
            return thatString;
        }
        return string.empty;
    }
}

and in your view, import the namespace where you have your extension method and call the method on your string property.

@Html.DisplayFor(modelItem => item.MainBiography.SubStringTo(10)) 

Answer 3

DisplayFor requires an expression that represents a property.

You can add a property to the model:

public string MainBiographyTrimmed
{
    get
    {
        if (MainBiography.Length) > 10
            return MainBiography.Substring(0, 10) + "...";
    }
}

Then in your view just do:

@Html.DisplayFor(item => item.MainBiographyTrimmed)

Answer 4

You're better off creating a different property in the model, to pick up the MainBiography and eventually cut it short.

Like this:

// This is your property (sampled)
public string MainBiography { get; set; }

//How long do you want your property to be at most ?
//(Best practice advices against magic numbers)
private int MainBiographyLimit = 100;

//You probably need this if you want to use .LabelFor() 
//and let this property mimic the "full" one  
[Display(Name="Main Biography")]
public string MainBiographyTrimmed
{
    get
    {
        if (this.MainBiography.Length > this.MainBiographyLimit)
            return this.MainBiography.Substring(0, this.MainBiographyLimit) + "...";
        else 
            return this.MainBiography;
    }
}

Usage would be

@Html.DisplayFor(item => item.MainBiographyTrimmed)

Another approach would be to build a full-fledged view model, but I find it overkill more often than not.