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Adds an "active" class to the given element when the route parameters match. An Active Page Tag Helper for use with Razor Pages.
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| [HtmlTargetElement(Attributes = "is-active-route")] | |
| public class ActiveRouteTagHelper : TagHelper | |
| { | |
| private IDictionary<string, string> _routeValues; | |
| /// <summary>The name of the action method.</summary> | |
| /// <remarks>Must be <c>null</c> if <see cref="P:Microsoft.AspNetCore.Mvc.TagHelpers.AnchorTagHelper.Route" /> is non-<c>null</c>.</remarks> | |
| [HtmlAttributeName("asp-action")] | |
| public string Action { get; set; } | |
| /// <summary>The name of the controller.</summary> | |
| /// <remarks>Must be <c>null</c> if <see cref="P:Microsoft.AspNetCore.Mvc.TagHelpers.AnchorTagHelper.Route" /> is non-<c>null</c>.</remarks> | |
| [HtmlAttributeName("asp-controller")] | |
| public string Controller { get; set; } | |
| /// <summary>Additional parameters for the route.</summary> | |
| [HtmlAttributeName("asp-all-route-data", DictionaryAttributePrefix = "asp-route-")] | |
| public IDictionary<string, string> RouteValues | |
| { | |
| get | |
| { | |
| if (this._routeValues == null) | |
| this._routeValues = (IDictionary<string, string>)new Dictionary<string, string>((IEqualityComparer<string>)StringComparer.OrdinalIgnoreCase); | |
| return this._routeValues; | |
| } | |
| set | |
| { | |
| this._routeValues = value; | |
| } | |
| } | |
| /// <summary> | |
| /// Gets or sets the <see cref="T:Microsoft.AspNetCore.Mvc.Rendering.ViewContext" /> for the current request. | |
| /// </summary> | |
| [HtmlAttributeNotBound] | |
| [ViewContext] | |
| public ViewContext ViewContext { get; set; } | |
| public override void Process(TagHelperContext context, TagHelperOutput output) | |
| { | |
| base.Process(context, output); | |
| if (ShouldBeActive()) | |
| { | |
| MakeActive(output); | |
| } | |
| } | |
| private bool ShouldBeActive() | |
| { | |
| string currentController = ViewContext.RouteData.Values["Controller"].ToString(); | |
| string currentAction = ViewContext.RouteData.Values["Action"].ToString(); | |
| if (!string.IsNullOrWhiteSpace(Controller) && Controller.ToLower() != currentController.ToLower()) | |
| { | |
| return false; | |
| } | |
| if (!string.IsNullOrWhiteSpace(Action) && Action.ToLower() != currentAction.ToLower()) | |
| { | |
| return false; | |
| } | |
| foreach (KeyValuePair<string, string> routeValue in RouteValues) | |
| { | |
| if (!ViewContext.RouteData.Values.ContainsKey(routeValue.Key) || | |
| ViewContext.RouteData.Values[routeValue.Key].ToString() != routeValue.Value) | |
| { | |
| return false; | |
| } | |
| } | |
| return true; | |
| } | |
| private void MakeActive(TagHelperOutput output) | |
| { | |
| var classAttr = output.Attributes.FirstOrDefault(a => a.Name == "class"); | |
| if (classAttr == null) | |
| { | |
| classAttr = new TagHelperAttribute("class", "active"); | |
| output.Attributes.Add(classAttr); | |
| } | |
| else if (classAttr.Value == null || classAttr.Value.ToString().IndexOf("active") < 0) | |
| { | |
| output.Attributes.SetAttribute("class", classAttr.Value == null | |
| ? "active" | |
| : classAttr.Value.ToString() + " active"); | |
| } | |
| } | |
| } |
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