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Adds an "active" class to the given element when the route parameters match. An Active Route Tag Helper.
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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); | |
} | |
output.Attributes.RemoveAll("is-active-route"); | |
} | |
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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