Question

Is there a smarter way to show/hide elements conditionally (with razor) than this below? The view is very large and I’m concerned about maintenance:

@if(@Model.Atendimento.PrazosEEntregas.Visivel)
{
    <div>
        <h4>Prazos e entrega do serviço</h4>

        @if (!string.IsNullOrWhiteSpace(@Model.Atendimento.PrazosEEntregas.PrazoFinalizacaoServico))
        {
            <p>@Model.Atendimento.PrazosEEntregas.PrazoFinalizacaoServico</p>
        }

        @if (!string.IsNullOrWhiteSpace(@Model.Atendimento.PrazosEEntregas.PrazoRetiradaDocumento))
        {
            <p><strong>Prazo de retirar o documento:</strong> @Model.Atendimento.PrazosEEntregas.PrazoRetiradaDocumento</p>
        }

        @if (!string.IsNullOrWhiteSpace(@Model.Atendimento.PrazosEEntregas.OndeRetirarServico))
        {
            <p><strong>Onde retirar/receber:</strong> @Model.Atendimento.PrazosEEntregas.OndeRetirarServico</p>
        }

        @if (!string.IsNullOrWhiteSpace(@Model.Atendimento.PrazosEEntregas.ObservacaoPrazoRetirada))
        {
            <p><strong>Observação:</strong> @Model.Atendimento.PrazosEEntregas.ObservacaoPrazoRetirada</p>
        }
    </div>
}

Thanks,
Hoisel

Answer 1

You could write a custom helper that will conditionally output the contents:

public static class HtmlExtensions
{
    public static IHtmlString FormatValue(
        this HtmlHelper htmlHelper, 
        string value, 
        string label
    )
    {
        if (string.IsNullOrWhiteSpace(value))
        {
            return MvcHtmlString.Empty;
        }

        var result = string.Format(
            "<p><strong>{0}</strong> {1}</p>",
            htmlHelper.Encode(label),
            htmlHelper.Encode(value)
        );
        return new HtmlString(value);
    }
}

and then:

@Html.FormatValue(
    Model.Atendimento.PrazosEEntregas.ObservacaoPrazoRetirada, 
    "Observação:"
)

Another possibility is to use a display template:

@Html.DisplayFor(x => x.Atendimento.PrazosEEntregas.ObservacaoPrazoRetirada)

Then you could define a display template for the string type (or a custom one):

@model string
@if (!string.IsNullOrWhiteSpace(Model))
{
    <p>
        <strong>@ViewData.ModelMetadata.DisplayName</strong>
        @ViewData.TemplateInfo.FormattedModelValue
    </p>
}

and on your view model:

[DisplayName("Observação:")]
[UIHint("MyTemplate")]
public string ObservacaoPrazoRetirada { get; set; }