Add transmission semantic for URI attribute values (#8826)

* Add transmission semantic for URI attribute values

Fixes #8813

* Add some comments, correct javadocs

* Fix GWT tests

* Use one magic method instead of another

* Check the type of JsonValue before read it

flow-client/src/main/java/com/vaadin/client/WidgetUtil.java

@@ -126,7 +126,7 @@ public static String toPrettyJson(JsonValue json) {
      * {@code value}.
      * <p>
      * If {@code value} is {@code null} then {@code attribute} is removed,
-     * otherwise {@code value.toString()} is set as its value.
+     * otherwise {@code value} is set as its value.
      *
      * @param element
      *            the DOM element owning attribute
@@ -136,11 +136,11 @@ public static String toPrettyJson(JsonValue json) {
      *            the value to update
      */
     public static void updateAttribute(Element element, String attribute,
-            Object value) {
+            String value) {
         if (value == null) {
             DomApi.wrap(element).removeAttribute(attribute);
         } else {
-            DomApi.wrap(element).setAttribute(attribute, value.toString());
+            DomApi.wrap(element).setAttribute(attribute, value);
         }
     }
 
@@ -227,7 +227,7 @@ public static native boolean hasJsProperty(Object object, String name)
     /**
      * Checks if the given value is explicitly undefined. <code>null</code>
      * values returns <code>false</code>.
-     * 
+     *
      * @param property
      *            the value to be verified
      * @return <code>true</code> is the value is explicitly undefined,

flow-client/src/main/java/com/vaadin/client/flow/binding/SimpleElementBindingStrategy.java

@@ -24,6 +24,7 @@
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.Scheduler;
 
+import com.vaadin.client.ApplicationConfiguration;
 import com.vaadin.client.Command;
 import com.vaadin.client.Console;
 import com.vaadin.client.ElementUtil;
@@ -290,9 +291,9 @@ private native void bindPolymerModelProperties(StateNode node,
     private native void hookUpPolymerElement(StateNode node, Element element)
     /*-{
         var self = this;
-    
+
         var originalPropertiesChanged = element._propertiesChanged;
-    
+
         if (originalPropertiesChanged) {
             element._propertiesChanged = function (currentProps, changedProps, oldProps) {
                 $entry(function () {
@@ -301,16 +302,16 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                 originalPropertiesChanged.apply(this, arguments);
             };
         }
-    
-    
+
+
         var tree = [email protected]::getTree()();
-    
+
         var originalReady = element.ready;
-    
+
         element.ready = function (){
             originalReady.apply(this, arguments);
             @com.vaadin.client.PolymerUtils::fireReadyEvent(*)(element);
-    
+
             // The  _propertiesChanged method which is replaced above for the element
             // doesn't do anything for items in dom-repeat.
             // Instead it's called with some meaningful info for the <code>dom-repeat</code> element.
@@ -319,7 +320,7 @@ private native void hookUpPolymerElement(StateNode node, Element element)
             // which changes this method for any dom-repeat instance.
             var replaceDomRepeatPropertyChange = function(){
                 var domRepeat = element.root.querySelector('dom-repeat');
-    
+
                 if ( domRepeat ){
                  // If the <code>dom-repeat</code> element is in the DOM then
                  // this method should not be executed anymore. The logic below will replace
@@ -333,12 +334,12 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                 // if dom-repeat is found => replace _propertiesChanged method in the prototype and mark it as replaced.
                 if ( !domRepeat.constructor.prototype.$propChangedModified){
                     domRepeat.constructor.prototype.$propChangedModified = true;
-    
+
                     var changed = domRepeat.constructor.prototype._propertiesChanged;
-    
+
                     domRepeat.constructor.prototype._propertiesChanged = function(currentProps, changedProps, oldProps){
                         changed.apply(this, arguments);
-    
+
                         var props = Object.getOwnPropertyNames(changedProps);
                         var items = "items.";
                         var i;
@@ -359,7 +360,7 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                                     if( currentPropsItem && currentPropsItem.nodeId ){
                                         var nodeId = currentPropsItem.nodeId;
                                         var value = currentPropsItem[propertyName];
-    
+
                                         // this is an attempt to find the template element
                                         // which is not available as a context in the protype method
                                         var host = this.__dataHost;
@@ -370,7 +371,7 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                                         while( !host.localName || host.__dataHost ){
                                             host = host.__dataHost;
                                         }
-    
+
                                         $entry(function () {
                                             @SimpleElementBindingStrategy::handleListItemPropertyChange(*)(nodeId, host, propertyName, value, tree);
                                         })();
@@ -381,7 +382,7 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                     };
                 }
             };
-    
+
             // dom-repeat doesn't have to be in DOM even if template has it
             //  such situation happens if there is dom-if e.g. which evaluates to <code>false</code> initially.
             // in this case dom-repeat is not yet in the DOM tree until dom-if becomes <code>true</code>
@@ -396,7 +397,7 @@ private native void hookUpPolymerElement(StateNode node, Element element)
                 element.addEventListener('dom-change',replaceDomRepeatPropertyChange);
             }
         }
-    
+
     }-*/;
 
     private static void handleListItemPropertyChange(double nodeId,
@@ -630,16 +631,21 @@ private void updateVisibility(JsArray<EventRemover> listeners,
     private void updateVisibility(Element element, NodeMap visibilityData,
             Boolean visibility) {
         storeInitialHiddenAttribute(element, visibilityData);
-        WidgetUtil.updateAttribute(element, HIDDEN_ATTRIBUTE, visibility);
+        updateAttributeValue(
+                visibilityData.getNode().getTree().getRegistry()
+                        .getApplicationConfiguration(),
+                element, HIDDEN_ATTRIBUTE, visibility);
     }
 
     private void restoreInitialHiddenAttribute(Element element,
             NodeMap visibilityData) {
         MapProperty initialVisibility = storeInitialHiddenAttribute(element,
                 visibilityData);
         if (initialVisibility.hasValue()) {
-            WidgetUtil.updateAttribute(element, HIDDEN_ATTRIBUTE,
-                    initialVisibility.getValue());
+            updateAttributeValue(
+                    visibilityData.getNode().getTree().getRegistry()
+                            .getApplicationConfiguration(),
+                    element, HIDDEN_ATTRIBUTE, initialVisibility.getValue());
         }
     }
 
@@ -734,7 +740,10 @@ private void updateStyleProperty(MapProperty mapProperty, Element element) {
 
     private void updateAttribute(MapProperty mapProperty, Element element) {
         String name = mapProperty.getName();
-        WidgetUtil.updateAttribute(element, name, mapProperty.getValue());
+        updateAttributeValue(
+                mapProperty.getMap().getNode().getTree().getRegistry()
+                        .getApplicationConfiguration(),
+                element, name, mapProperty.getValue());
     }
 
     private EventRemover bindChildren(BindingContext context) {
@@ -1366,6 +1375,35 @@ private EventRemover bindClientCallableMethods(BindingContext context) {
                 (Element) context.htmlNode, context.node);
     }
 
+    private static void updateAttributeValue(
+            ApplicationConfiguration configuration, Element element,
+            String attribute, Object value) {
+        if (value == null || value instanceof String) {
+            WidgetUtil.updateAttribute(element, attribute, (String) value);
+        } else {
+            JsonValue jsonValue = WidgetUtil.crazyJsoCast(value);
+            if (JsonType.OBJECT.equals(jsonValue.getType())) {
+                JsonObject object = (JsonObject) jsonValue;
+                assert object.hasKey(
+                        NodeProperties.URI_ATTRIBUTE) : "Implementation error: JsonObject is recieved as an attribute value for '"
+                                + attribute + "' but it has no "
+                                + NodeProperties.URI_ATTRIBUTE + " key";
+                String uri = object.getString(NodeProperties.URI_ATTRIBUTE);
+                if (configuration.isWebComponentMode()) {
+                    String baseUri = configuration.getServiceUrl();
+                    baseUri = baseUri.endsWith("/") ? baseUri : baseUri + "/";
+                    WidgetUtil.updateAttribute(element, attribute,
+                            baseUri + uri);
+                } else {
+                    WidgetUtil.updateAttribute(element, attribute, uri);
+                }
+            } else {
+                WidgetUtil.updateAttribute(element, attribute,
+                        value.toString());
+            }
+        }
+    }
+
     private static EventExpression getOrCreateExpression(
             String expressionString) {
         if (expressionCache == null) {

flow-client/src/test-gwt/java/com/vaadin/client/flow/GwtEventHandlerTest.java

@@ -21,6 +21,7 @@
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
+import com.vaadin.client.ApplicationConfiguration;
 import com.vaadin.client.ClientEngineTestBase;
 import com.vaadin.client.Registry;
 import com.vaadin.client.WidgetUtil;
@@ -66,6 +67,8 @@ protected void gwtSetUp() throws Exception {
         registry = new Registry() {
             {
                 set(ConstantPool.class, new ConstantPool());
+                set(ApplicationConfiguration.class,
+                        new ApplicationConfiguration());
             }
         };
 
@@ -138,7 +141,8 @@ public void testClientCallablePromises() {
         delayTestFinish(100);
     }
 
-    private static native void addThen(Object promise, Consumer<String> callback)
+    private static native void addThen(Object promise,
+            Consumer<String> callback)
     /*-{
         promise.then($entry(function(value) {
             callback.@Consumer::accept(*)(value);

flow-client/src/test-gwt/java/com/vaadin/client/flow/GwtMultipleBindingTest.java

@@ -15,6 +15,7 @@
  */
 package com.vaadin.client.flow;
 
+import com.vaadin.client.ApplicationConfiguration;
 import com.vaadin.client.ClientEngineTestBase;
 import com.vaadin.client.ExistingElementMap;
 import com.vaadin.client.Registry;
@@ -91,6 +92,8 @@ protected void gwtSetUp() throws Exception {
             {
                 set(ConstantPool.class, new ConstantPool());
                 set(ExistingElementMap.class, new ExistingElementMap());
+                set(ApplicationConfiguration.class,
+                        new ApplicationConfiguration());
             }
         };
 

flow-client/src/test-gwt/java/com/vaadin/client/flow/GwtPropertyElementBinderTest.java

@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import com.vaadin.client.ApplicationConfiguration;
 import com.vaadin.client.ClientEngineTestBase;
 import com.vaadin.client.ExistingElementMap;
 import com.vaadin.client.InitialPropertiesHandler;
@@ -58,6 +59,7 @@ private static class TestRegistry extends Registry {
                 ExistingElementMap existingElementMap) {
             this.constantPool = constantPool;
             this.existingElementMap = existingElementMap;
+            set(ApplicationConfiguration.class, new ApplicationConfiguration());
         }
 
         @Override

flow-server/src/main/java/com/vaadin/flow/internal/nodefeature/ElementAttributeMap.java

@@ -34,6 +34,9 @@
 import com.vaadin.flow.server.VaadinSession;
 import com.vaadin.flow.shared.Registration;
 
+import elemental.json.Json;
+import elemental.json.JsonObject;
+
 /**
  * Map for element attribute values.
  *
@@ -65,8 +68,7 @@ public ElementAttributeMap(StateNode node) {
      *            the value
      */
     public void set(String attribute, String value) {
-        unregisterResource(attribute);
-        put(attribute, value);
+        doSet(attribute, value);
     }
 
     /**
@@ -103,7 +105,19 @@ public Serializable remove(String attribute) {
      */
     @Override
     public String get(String attribute) {
-        return (String) super.get(attribute);
+        Serializable value = super.get(attribute);
+        if (value == null || value instanceof String) {
+            return (String) value;
+        } else {
+            // If the value is not a string then current impl only uses
+            // JsonObject
+            assert value instanceof JsonObject;
+            JsonObject object = (JsonObject) value;
+            // The only object which may be set by the current imlp contains
+            // "uri" attribute, only this situation is expected here.
+            assert object.hasKey(NodeProperties.URI_ATTRIBUTE);
+            return object.getString(NodeProperties.URI_ATTRIBUTE);
+        }
     }
 
     /**
@@ -142,7 +156,11 @@ private void doSetResource(String attribute,
         } else {
             targetUri = StreamResourceRegistry.getURI(resource);
         }
-        set(attribute, targetUri.toASCIIString());
+        JsonObject object = Json.createObject();
+        object.put(NodeProperties.URI_ATTRIBUTE, targetUri.toASCIIString());
+        // don't use sring as a value, but wrap it into an object to let know
+        // the client side about specific nature of the value
+        doSet(attribute, object);
     }
 
     private void ensurePendingRegistrations() {
@@ -225,6 +243,11 @@ public void execute() {
                 }));
     }
 
+    private void doSet(String attribute, Serializable value) {
+        unregisterResource(attribute);
+        put(attribute, value);
+    }
+
     private void unsetResource(String attribute) {
         ensureResourceRegistrations();
         StreamRegistration registration = resourceRegistrations.get(attribute);

flow-server/src/main/java/com/vaadin/flow/internal/nodefeature/NodeProperties.java

@@ -87,6 +87,14 @@ public final class NodeProperties {
      */
     public static final String VISIBILITY_HIDDEN_PROPERTY = "hidden";
 
+    /**
+     * The property in Json object which marks the object as special value
+     * transmitting URI (not just any string).
+     * <p>
+     * Used in the {@link ElementAttributeMap}.
+     */
+    public static final String URI_ATTRIBUTE = "uri";
+
     private NodeProperties() {
     }
 }

flow-tests/test-embedding/embedding-test-assets/src/main/java/com/vaadin/flow/webcomponent/ClientSelectComponent.java

@@ -15,15 +15,18 @@
  */
 package com.vaadin.flow.webcomponent;
 
+import java.io.ByteArrayInputStream;
 import java.util.Optional;
 
 import com.vaadin.flow.component.AbstractField;
 import com.vaadin.flow.component.AttachEvent;
 import com.vaadin.flow.component.Component;
 import com.vaadin.flow.component.Tag;
 import com.vaadin.flow.component.dependency.JsModule;
+import com.vaadin.flow.component.html.Anchor;
 import com.vaadin.flow.component.html.Div;
 import com.vaadin.flow.component.html.Span;
+import com.vaadin.flow.server.StreamResource;
 
 @JsModule("./src/Dependency.js")
 public class ClientSelectComponent extends Div {
@@ -42,13 +45,26 @@ public ClientSelectComponent() {
         select.addValueChangeListener(this::setValue);
 
         add(select, message);
+        Anchor getPdf = new Anchor();
+        getPdf.setText("Download PDF");
+        getPdf.setId("link");
+        getPdf.setHref(createPdfStreamResource());
+        getPdf.getElement().setAttribute("download", true);
+        add(getPdf);
     }
 
     @Override
     protected void onAttach(AttachEvent attachEvent) {
         add(new DepElement());
     }
 
+    private StreamResource createPdfStreamResource() {
+        StreamResource streamResource = new StreamResource("label.pdf",
+                () -> new ByteArrayInputStream(new byte[] { 1 }));
+        streamResource.setContentType("application/pdf");
+        return streamResource;
+    }
+
     private void setValue(
             AbstractField.ComponentValueChangeEvent<Select, String> event) {
         String messageText = "No selection";