Adding paging links in RFC GeoJSON output format, and paging HTTP hea…

…ders for all formats

src/community/wfs3/src/main/java/org/geoserver/wfs3/response/HttpHeaderLinksAppender.java

@@ -0,0 +1,41 @@
+/* (c) 2018 Open Source Geospatial Foundation - all rights reserved
+ * This code is licensed under the GPL 2.0 license, available at the root
+ * application directory.
+ */
+package org.geoserver.wfs3.response;
+
+import javax.servlet.http.HttpServletResponse;
+import org.geoserver.ows.AbstractDispatcherCallback;
+import org.geoserver.ows.Request;
+import org.geoserver.ows.Response;
+import org.geoserver.platform.Operation;
+import org.geoserver.wfs.request.FeatureCollectionResponse;
+
+/** Appends paging links as HTTP headers for GetFeature responses */
+public class HttpHeaderLinksAppender extends AbstractDispatcherCallback {
+
+    @Override
+    public Response responseDispatched(
+            Request request, Operation operation, Object result, Response response) {
+        // is this a feature response we are about to encode?
+        if (result instanceof FeatureCollectionResponse) {
+            HttpServletResponse httpResponse = request.getHttpResponse();
+            FeatureCollectionResponse fcr = (FeatureCollectionResponse) result;
+            String contentType = response.getMimeType(result, operation);
+            if (fcr.getPrevious() != null) {
+                addLink(httpResponse, "prev", contentType, fcr.getPrevious());
+            }
+            if (fcr.getNext() != null) {
+                addLink(httpResponse, "next", contentType, fcr.getNext());
+            }
+        }
+
+        return response;
+    }
+
+    private void addLink(
+            HttpServletResponse httpResponse, String rel, String contentType, String href) {
+        String headerValue = String.format("<%s>; rel=\"%s\"; type=\"%s\"", href, rel, contentType);
+        httpResponse.addHeader("Link", headerValue);
+    }
+}

src/community/wfs3/src/main/java/org/geoserver/wfs3/response/RFCGeoJSONFeaturesResponse.java

@@ -111,23 +111,38 @@ protected void writeExtraFeatureProperties(
             Feature feature, Operation operation, GeoJSONBuilder jw) {
         String featureId = WFS3_FEATURE_ID.get();
         if (featureId != null) {
-            writeLinks(operation, jw, featureId);
+            writeLinks(null, operation, jw, featureId);
         }
     }
 
     @Override
-    protected void writeExtraCollectionProperties(
+    protected void writePagingLinks(
             FeatureCollectionResponse response, Operation operation, GeoJSONBuilder jw) {
-        writeLinks(operation, jw, null);
+        // we have more than just paging links here
+        writeLinks(response, operation, jw, null);
     }
 
-    private void writeLinks(Operation operation, GeoJSONBuilder jw, String featureId) {
+    private void writeLinks(
+            FeatureCollectionResponse response,
+            Operation operation,
+            GeoJSONBuilder jw,
+            String featureId) {
         List<String> formats = getAvailableFormats(FeatureCollectionResponse.class);
         GetFeatureRequest request = GetFeatureRequest.adapt(operation.getParameters()[0]);
         FeatureTypeInfo featureType = getFeatureType(request);
         String baseUrl = request.getBaseUrl();
         jw.key("links");
         jw.array();
+        // paging links
+        if (response != null) {
+            if (response.getPrevious() != null) {
+                writeLink(jw, "Previous page", MIME, "prev", response.getPrevious());
+            }
+            if (response.getNext() != null) {
+                writeLink(jw, "Next page", MIME, "next", response.getNext());
+            }
+        }
+        // alternate/self links
         for (String format : formats) {
             String path = "wfs3/collections/" + NCNameResourceCodec.encode(featureType) + "/items";
             if (featureId != null) {

src/community/wfs3/src/main/resources/applicationContext.xml

@@ -133,5 +133,6 @@
     </property>
   </bean>
 
+  <bean id="headerLinksAppender" class="org.geoserver.wfs3.response.HttpHeaderLinksAppender"/>
 
 </beans>

src/community/wfs3/src/test/java/org/geoserver/wfs3/FeatureTest.java

@@ -6,6 +6,7 @@
 
 import static org.hamcrest.CoreMatchers.both;
 import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
@@ -14,11 +15,14 @@
 import com.jayway.jsonpath.DocumentContext;
 import java.util.List;
 import java.util.Map;
+import net.minidev.json.JSONArray;
 import org.geoserver.data.test.MockData;
 import org.geoserver.ows.util.KvpUtils;
 import org.geoserver.ows.util.ResponseUtils;
+import org.hamcrest.Matchers;
 import org.jsoup.nodes.Document;
 import org.junit.Test;
+import org.springframework.mock.web.MockHttpServletResponse;
 
 public class FeatureTest extends WFS3TestSupport {
 
@@ -158,11 +162,82 @@ public void testSingleFeatureAsGeoJson() throws Exception {
     }
 
     @Test
-    public void testLimit() throws Exception {
+    public void testFirstPage() throws Exception {
+        String expectedNextURL =
+                "http://localhost:8080/geoserver/wfs3/collections/cite__RoadSegments/items?startIndex=3&limit=3";
+
         String roadSegments = getEncodedName(MockData.ROAD_SEGMENTS);
-        DocumentContext json =
-                getAsJSONPath("wfs3/collections/" + roadSegments + "/items?limit=3", 200);
+        MockHttpServletResponse response =
+                getAsMockHttpServletResponse(
+                        "wfs3/collections/" + roadSegments + "/items?limit=3", 200);
+        List<String> links = response.getHeaders("Link");
+        assertThat(links, Matchers.hasSize(1));
+        assertEquals(
+                links.get(0),
+                "<" + expectedNextURL + ">; rel=\"next\"; type=\"application/geo+json\"");
+
+        DocumentContext json = getAsJSONPath(response);
         assertEquals(3, (int) json.read("features.length()", Integer.class));
+        // check the paging link is there
+        assertThat(json.read("$.links[?(@.rel=='prev')].href"), Matchers.empty());
+        assertThat(
+                json.read("$.links[?(@.rel=='next')].href", JSONArray.class).get(0),
+                equalTo(expectedNextURL));
+    }
+
+    @Test
+    public void testMiddlePage() throws Exception {
+        String expectedPrevURL =
+                "http://localhost:8080/geoserver/wfs3/collections/cite__RoadSegments/items?startIndex=2&limit=1";
+        String expectedNextURL =
+                "http://localhost:8080/geoserver/wfs3/collections/cite__RoadSegments/items?startIndex=4&limit=1";
+
+        String roadSegments = getEncodedName(MockData.ROAD_SEGMENTS);
+        MockHttpServletResponse response =
+                getAsMockHttpServletResponse(
+                        "wfs3/collections/" + roadSegments + "/items?startIndex=3&limit=1", 200);
+        List<String> links = response.getHeaders("Link");
+        assertThat(links, Matchers.hasSize(2));
+        assertEquals(
+                links.get(0),
+                "<" + expectedPrevURL + ">; rel=\"prev\"; type=\"application/geo+json\"");
+        assertEquals(
+                links.get(1),
+                "<" + expectedNextURL + ">; rel=\"next\"; type=\"application/geo+json\"");
+
+        DocumentContext json = getAsJSONPath(response);
+        assertEquals(1, (int) json.read("features.length()", Integer.class));
+        // check the paging link is there
+        assertThat(
+                json.read("$.links[?(@.rel=='prev')].href", JSONArray.class).get(0),
+                equalTo(expectedPrevURL));
+        assertThat(
+                json.read("$.links[?(@.rel=='next')].href", JSONArray.class).get(0),
+                equalTo(expectedNextURL));
+    }
+
+    @Test
+    public void testLastPage() throws Exception {
+        String expectedPrevLink =
+                "http://localhost:8080/geoserver/wfs3/collections/cite__RoadSegments/items?startIndex=0&limit=3";
+
+        String roadSegments = getEncodedName(MockData.ROAD_SEGMENTS);
+        MockHttpServletResponse response =
+                getAsMockHttpServletResponse(
+                        "wfs3/collections/" + roadSegments + "/items?startIndex=3&limit=3", 200);
+        List<String> links = response.getHeaders("Link");
+        assertThat(links, Matchers.hasSize(1));
+        assertEquals(
+                links.get(0),
+                "<" + expectedPrevLink + ">; rel=\"prev\"; type=\"application/geo+json\"");
+
+        DocumentContext json = getAsJSONPath(response);
+        assertEquals(2, (int) json.read("features.length()", Integer.class));
+        // check the paging link is there
+        assertThat(
+                json.read("$.links[?(@.rel=='prev')].href", JSONArray.class).get(0),
+                equalTo(expectedPrevLink));
+        assertThat(json.read("$.links[?(@.rel=='next')].href"), Matchers.empty());
     }
 
     @Test

src/community/wfs3/src/test/java/org/geoserver/wfs3/WFS3TestSupport.java

@@ -12,6 +12,7 @@
 import com.jayway.jsonpath.DocumentContext;
 import com.jayway.jsonpath.JsonPath;
 import com.jayway.jsonpath.internal.JsonContext;
+import java.io.UnsupportedEncodingException;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -44,9 +45,12 @@ protected String getEncodedName(QName qName) {
     }
 
     protected DocumentContext getAsJSONPath(String path, int expectedHttpCode) throws Exception {
-        MockHttpServletResponse response = getAsServletResponse(path);
+        MockHttpServletResponse response = getAsMockHttpServletResponse(path, expectedHttpCode);
+        return getAsJSONPath(response);
+    }
 
-        assertEquals(expectedHttpCode, response.getStatus());
+    protected DocumentContext getAsJSONPath(MockHttpServletResponse response)
+            throws UnsupportedEncodingException {
         assertThat(
                 response.getContentType(),
                 anyOf(startsWith("application/json"), startsWith("application/geo+json")));
@@ -57,6 +61,14 @@ protected DocumentContext getAsJSONPath(String path, int expectedHttpCode) throw
         return json;
     }
 
+    protected MockHttpServletResponse getAsMockHttpServletResponse(
+            String path, int expectedHttpCode) throws Exception {
+        MockHttpServletResponse response = getAsServletResponse(path);
+
+        assertEquals(expectedHttpCode, response.getStatus());
+        return response;
+    }
+
     @Override
     protected void onSetUp(SystemTestData testData) {
         // init xmlunit
@@ -70,8 +82,7 @@ protected void onSetUp(SystemTestData testData) {
     }
 
     protected Document getAsJSoup(String url) throws Exception {
-        MockHttpServletResponse response = getAsServletResponse(url);
-        assertEquals(200, response.getStatus());
+        MockHttpServletResponse response = getAsMockHttpServletResponse(url, 200);
         assertEquals("text/html", response.getContentType());
 
         LOGGER.log(Level.INFO, "Last request returned\n:" + response.getContentAsString());