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copied!<p>One solution is to implement your own extension method on HtmlHelper that does something different to the default ValidationMessageFor behavior. The sample @Html.ValidationMessagesFor method below will concatenate multiple error messages that have been added to the ModelState during <em>server-side</em> validation (only).</p> <pre><code>public static MvcHtmlString ValidationMessagesFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object htmlAttributes = null) { var propertyName = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData).PropertyName; var modelState = htmlHelper.ViewData.ModelState; // If we have multiple (server-side) validation errors, collect and present them. if (modelState.ContainsKey(propertyName) && modelState[propertyName].Errors.Count > 1) { var msgs = new StringBuilder(); foreach (ModelError error in modelState[propertyName].Errors) { msgs.AppendLine(error.ErrorMessage); } // Return standard ValidationMessageFor, overriding the message with our concatenated list of messages. return htmlHelper.ValidationMessageFor(expression, msgs.ToString(), htmlAttributes as IDictionary<string, object> ?? htmlAttributes); } // Revert to default behaviour. return htmlHelper.ValidationMessageFor(expression, null, htmlAttributes as IDictionary<string, object> ?? htmlAttributes); } </code></pre> <p>This is useful if you have custom business validation you're applying across a collection belonging to your model (for example, cross-checking totals), or checking the model as a whole.</p> <p>An example using this, where a collection of Order.LineItems are validated server-side:</p> <pre><code>@using MyHtmlHelperExtensions // namespace containing ValidationMessagesFor @using (Html.BeginForm()) { @Html.LabelFor(m => m.LineItems) <ul> @Html.EditorFor(m => m.LineItems) </ul> @Html.ValidationMessagesFor(m => m.LineItems) } </code></pre>

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