feat: provide an API to make router ignore an anchor (#17745)

Anchors in Vaadin are simply broken if the url happens to be relative. With this API that can be fixed.

Fixes #17617

---------

Co-authored-by: Mikael Grankvist <mgrankvi@vaadin.com>
Co-authored-by: caalador <mikael.grankvist@vaadin.com>

Author: mstahv

flow-html-components/src/main/java/com/vaadin/flow/component/html/Anchor.java

@@ -170,10 +170,32 @@ public void removeHref() {
      */
     public void setHref(AbstractStreamResource href) {
         this.href = href;
-        getElement().setAttribute(ROUTER_IGNORE_ATTRIBUTE, true);
+        setRouterIgnore(true);
         assignHrefAttribute();
     }
 
+    /**
+     * The routing mechanism in Vaadin by default intercepts all anchor elements
+     * with relative URL. This method can be used make the router ignore this
+     * anchor and this way make this anchor behave normally and cause a full
+     * page load.
+     *
+     * @param ignore
+     *            true if this link should not be intercepted by the single-page
+     *            web application routing mechanism in Vaadin.
+     */
+    public void setRouterIgnore(boolean ignore) {
+        getElement().setAttribute(ROUTER_IGNORE_ATTRIBUTE, ignore);
+    }
+
+    /**
+     * @return true if this anchor should be ignored by the Vaadin router and
+     *         behave normally.
+     */
+    public boolean isRouterIgnore() {
+        return getElement().hasAttribute(ROUTER_IGNORE_ATTRIBUTE);
+    }
+
     /**
      * Gets the URL that this anchor links to.
      *

flow-html-components/src/test/java/com/vaadin/flow/component/html/AnchorTest.java

@@ -138,6 +138,8 @@ public void getTargetValue_useSomeStringValue_targetIsReturned() {
     protected void addProperties() {
         addStringProperty("href", "", false);
         addOptionalStringProperty("target");
+        addProperty("routerIgnore", boolean.class, false, true, false, true,
+                "router-ignore");
     }
 
     @Test

flow-html-components/src/test/java/com/vaadin/flow/component/html/ComponentProperty.java

@@ -23,6 +23,7 @@
 
 public class ComponentProperty {
     public String name;
+    public String propertyOrAttributeTag;
     public Object defaultValue, otherValue;
     public boolean optional;
     public boolean removeDefault;
@@ -34,13 +35,18 @@ public <T> ComponentProperty(Class<? extends Component> componentType,
             boolean optional, boolean removeDefault) {
         this.componentType = componentType;
         this.name = name;
+        this.propertyOrAttributeTag = name;
         this.type = type;
         this.defaultValue = defaultValue;
         this.optional = optional;
         this.removeDefault = removeDefault;
         this.otherValue = otherValue == null ? name + name : otherValue;
     }
 
+    public void setPropertyOrAttributeTag(String propertyOrAttributeTag) {
+        this.propertyOrAttributeTag = propertyOrAttributeTag;
+    }
+
     public boolean isOptional() {
         return optional;
     }

flow-html-components/src/test/java/com/vaadin/flow/component/html/ComponentTest.java

@@ -109,6 +109,16 @@ protected <U> void addProperty(String propertyName, Class<U> propertyType,
                 isOptional, removeDefault));
     }
 
+    protected <U> void addProperty(String propertyName, Class<U> propertyType,
+            U defaultValue, U otherValue, boolean isOptional,
+            boolean removeDefault, String propertyOrAttributeTag) {
+        ComponentProperty property = new ComponentProperty(
+                getComponent().getClass(), propertyName, propertyType,
+                defaultValue, otherValue, isOptional, removeDefault);
+        property.setPropertyOrAttributeTag(propertyOrAttributeTag);
+        properties.add(property);
+    }
+
     protected Component createComponent() throws InstantiationException,
             IllegalAccessException, ClassNotFoundException {
         String componentClass = getClass().getName().replace("Test", "");
@@ -370,7 +380,8 @@ private void assertNonDefaultValues() throws Exception {
                 Assert.assertEquals(property.otherValue,
                         property.getUsingGetter(component));
             }
-            assertPropertyOrAttribute(component, property.name);
+            assertPropertyOrAttribute(component,
+                    property.propertyOrAttributeTag);
         }
     }