/// <summary>
/// Show a partial view for a part of the view's model.
/// </summary>
/// <typeparam name="TModel">The type of the main model.</typeparam>
/// <typeparam name="TField">The type of the part in the model.</typeparam>
/// <param name="htmlHelper">The HTML helper.</param>
/// <param name="partialViewName">The name of the partial view template.</param>
/// <param name="modelPropertyExpression">An expression that defines the part inside the main model.</param>
/// <returns>Returns the rendered partial view.</returns>
/// <remarks>
/// This method takes care of the model prefix which the partial view must include
/// in its input field expressions.
/// </remarks>
public static Task <IHtmlContent> PartialForAsync <TModel, TField>(
this IHtmlHelper <TModel> htmlHelper,
string partialViewName,
Expression <Func <TModel, TField> > modelPropertyExpression)
{
if (htmlHelper == null)
{
throw new ArgumentNullException(nameof(htmlHelper));
}
if (partialViewName == null)
{
throw new ArgumentNullException(nameof(partialViewName));
}
if (modelPropertyExpression == null)
{
throw new ArgumentNullException(nameof(modelPropertyExpression));
}
var viewData = htmlHelper.ViewData;
string propertyName = GenericExpressionHelper.GetExpressionText(modelPropertyExpression);
string fullPropertyName = viewData.TemplateInfo.GetFullHtmlFieldName(propertyName);
TField propertyValue = modelPropertyExpression.Compile().Invoke(viewData.Model);
var partialViewData = new ViewDataDictionary(viewData);
partialViewData.TemplateInfo.HtmlFieldPrefix = fullPropertyName;
return(htmlHelper.PartialAsync(partialViewName, propertyValue, partialViewData));
}
private static ModelMetadata GetPropertyMetadata <TModel, TField>(IHtmlHelper <TModel> htmlHelper, Expression <Func <TModel, TField> > modelPropertyExpression)
{
var modelExpression = GenericExpressionHelper.CreateModelExpression(htmlHelper.ViewData, modelPropertyExpression);
return(modelExpression.Metadata);
}
