Add geojson parsing support

build.gradle

@@ -31,12 +31,16 @@ sourceCompatibility = '1.8'
 
 dependencies {
     // Be sure to update dependencies in pom.xml to match
-    implementation 'joda-time:joda-time:2.10.10'
-    implementation 'org.slf4j:slf4j-api:1.7.31'
+    implementation 'joda-time:joda-time:2.10.13'
+    implementation 'org.slf4j:slf4j-api:1.7.33'
+    implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.1'
+
     // Upgrade to version higher than 1.4 when Collect minSDK >= 26
     implementation 'org.apache.commons:commons-csv:1.4'
+
     compileOnly 'net.sf.kxml:kxml2:2.3.0'
-    testImplementation 'ch.qos.logback:logback-classic:1.2.3'
+
+    testImplementation 'ch.qos.logback:logback-classic:1.2.10'
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'net.sf.kxml:kxml2:2.3.0'
     testImplementation 'org.hamcrest:hamcrest-all:1.3'

pom.xml

@@ -56,6 +56,11 @@
        <version>2.10.10</version>
        <scope>compile</scope>
     </dependency>
+    <dependency>
+      <groupId>com.fasterxml.jackson.core</groupId>
+      <artifactId>jackson-databind</artifactId>
+      <version>2.13.1</version>
+    </dependency>
     <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-csv</artifactId>

src/main/java/org/javarosa/core/model/instance/ExternalDataInstance.java

@@ -4,6 +4,7 @@
 import java.io.DataOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import org.javarosa.core.model.instance.geojson.GeoJsonExternalInstance;
 import org.javarosa.core.reference.InvalidReferenceException;
 import org.javarosa.core.reference.ReferenceManager;
 import org.javarosa.core.util.externalizable.DeserializationException;
@@ -68,10 +69,12 @@ public static ExternalDataInstance build(String instanceSrc, String instanceId)
         return new ExternalDataInstance(root, instanceId, instanceSrc);
     }
 
-    private static TreeElement parseExternalInstance(String instanceSrc, String instanceId) throws IOException, InvalidReferenceException, InvalidStructureException, XmlPullParserException, UnfullfilledRequirementsException {
+    private static TreeElement parseExternalInstance(String instanceSrc, String instanceId)
+        throws IOException, InvalidReferenceException, InvalidStructureException, XmlPullParserException, UnfullfilledRequirementsException {
         String path = getPath(instanceSrc);
-        return instanceSrc.contains("file-csv") ?
-            CsvExternalInstance.parse(instanceId, path) : XmlExternalInstance.parse(instanceId, path);
+        return instanceSrc.contains("file-csv") ? CsvExternalInstance.parse(instanceId, path)
+            : instanceSrc.endsWith("geojson") ? GeoJsonExternalInstance.parse(instanceId, path)
+            : XmlExternalInstance.parse(instanceId, path);
     }
 
     @Override

src/main/java/org/javarosa/core/model/instance/geojson/GeoJsonExternalInstance.java

@@ -0,0 +1,55 @@
+package org.javarosa.core.model.instance.geojson;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import org.javarosa.core.model.instance.TreeElement;
+
+public class GeoJsonExternalInstance {
+    public static TreeElement parse(String instanceId, String path) throws IOException {
+        return parse(instanceId, new FileInputStream(path));
+    }
+
+    protected static TreeElement parse(String instanceId, InputStream geojsonStream) throws IOException {
+        final TreeElement root = new TreeElement("root", 0);
+        root.setInstanceName(instanceId);
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        try (JsonParser jsonParser = objectMapper.getFactory().createParser(geojsonStream)) {
+            validatePreamble(jsonParser);
+
+            int multiplicity = 0;
+            while (jsonParser.nextToken() != JsonToken.END_ARRAY) {
+                GeojsonFeature feature = objectMapper.readValue(jsonParser, GeojsonFeature.class);
+
+                root.addChild(feature.toTreeElement(multiplicity));
+                multiplicity++;
+            }
+        }
+
+        return root;
+    }
+
+    private static void validatePreamble(JsonParser jsonParser) throws IOException {
+        if (jsonParser.nextToken() != JsonToken.START_OBJECT) {
+            throw new IOException("GeoJSON file must contain a top-level Object");
+        }
+
+        jsonParser.nextToken();
+        String propertyName = jsonParser.getCurrentName();
+        jsonParser.nextToken();
+        if (!(propertyName.equals("type") && jsonParser.getValueAsString().equals("FeatureCollection"))) {
+            throw new IOException("GeoJSON file must contain a top-level FeatureCollection");
+        }
+
+        jsonParser.nextToken();
+        propertyName = jsonParser.getCurrentName();
+
+        if (!(propertyName.equals("features") && jsonParser.nextToken() == JsonToken.START_ARRAY)) {
+            throw new IOException("GeoJSON FeatureCollection must contain an array of features");
+        }
+    }
+}

src/main/java/org/javarosa/core/model/instance/geojson/GeojsonFeature.java

@@ -0,0 +1,29 @@
+package org.javarosa.core.model.instance.geojson;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import java.util.Map;
+import org.javarosa.core.model.data.UncastData;
+import org.javarosa.core.model.instance.TreeElement;
+
+@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY)
+public class GeojsonFeature {
+    private String type;
+    private GeojsonGeometry geometry;
+    private Map<String, String> properties;
+
+    public TreeElement toTreeElement(int multiplicity) {
+        TreeElement item = new TreeElement("item", multiplicity);
+
+        TreeElement geoField = new TreeElement("geometry", 0);
+        geoField.setValue(new UncastData(geometry.getOdkCoordinates()));
+        item.addChild(geoField);
+
+       for (String property : properties.keySet()) {
+           TreeElement field = new TreeElement(property, 0);
+           field.setValue(new UncastData(properties.get(property)));
+           item.addChild(field);
+       }
+
+       return item;
+    }
+}

src/main/java/org/javarosa/core/model/instance/geojson/GeojsonGeometry.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2022 ODK
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.javarosa.core.model.instance.geojson;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import java.util.ArrayList;
+
+@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY)
+public class GeojsonGeometry {
+    private String type;
+    private ArrayList<String> coordinates;
+
+    public String getType() {
+        return type;
+    }
+
+    public String getOdkCoordinates() {
+        if (!(type.equals("Point") && coordinates.size() == 2)) {
+            throw new UnsupportedOperationException("Only Points are currently supported");
+        }
+
+        return coordinates.get(0) + " " + coordinates.get(1) + " 0 0";
+    }
+}

src/main/java/org/javarosa/core/util/GeoUtils.java

@@ -21,18 +21,17 @@
 
 package org.javarosa.core.util;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.util.ArrayList;
-import java.util.List;
-
+import static java.lang.Math.PI;
 import static java.lang.Math.abs;
 import static java.lang.Math.acos;
 import static java.lang.Math.cos;
 import static java.lang.Math.sin;
 import static java.lang.Math.toRadians;
-import static java.lang.Math.PI;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Author: Meletis Margaritis

src/test/java/org/javarosa/core/model/instance/geojson/GeoJsonExternalInstanceTest.java

@@ -0,0 +1,135 @@
+package org.javarosa.core.model.instance.geojson;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.fail;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import org.javarosa.core.model.instance.TreeElement;
+import org.junit.Test;
+
+public class GeoJsonExternalInstanceTest {
+    @Test
+    public void parse_throwsException_ifTopLevelElementNotFeatureCollection() {
+        try {
+            GeoJsonExternalInstance.parse("id", new ByteArrayInputStream(GEOMETRY_COLLECTION_GEOJSON.getBytes(StandardCharsets.UTF_8)));
+            fail("Exception expected");
+        } catch (IOException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void parse_parsesMultipleFeatures() throws IOException {
+        TreeElement featureCollection = GeoJsonExternalInstance.parse("id", new ByteArrayInputStream(FEATURE_COLLECTION_GEOJSON.getBytes(StandardCharsets.UTF_8)));
+        assertThat(featureCollection.getNumChildren(), is(2));
+    }
+
+    @Test
+    public void parse_addsGeometryAsChild() throws IOException {
+        TreeElement featureCollection = GeoJsonExternalInstance.parse("id", new ByteArrayInputStream(FEATURE_COLLECTION_GEOJSON.getBytes(StandardCharsets.UTF_8)));
+        assertThat(featureCollection.getChildAt(0).getChild("geometry", 0).getValue().getValue(), is("102 0.5 0 0"));
+        assertThat(featureCollection.getChildAt(1).getChild("geometry", 0).getValue().getValue(), is("104 0.5 0 0"));
+    }
+
+    @Test
+    public void parse_addsAllOtherPropertiesAsChildren() throws IOException {
+        TreeElement featureCollection = GeoJsonExternalInstance.parse("id", new ByteArrayInputStream(FEATURE_COLLECTION_GEOJSON.getBytes(StandardCharsets.UTF_8)));
+        assertThat(featureCollection.getChildAt(0).getNumChildren(), is(4));
+        assertThat(featureCollection.getChildAt(0).getChild("name", 0).getValue().getValue(), is("My cool point"));
+
+        assertThat(featureCollection.getChildAt(1).getNumChildren(), is(5));
+        assertThat(featureCollection.getChildAt(1).getChild("special-property", 0).getValue().getValue(), is("special value"));
+    }
+
+    @Test
+    public void getOdkCoordinates_convertsPointGeoJsonGeometry() throws IOException {
+        String point = "{ \"type\": \"Point\", \"coordinates\": [ 102, 0.5 ] }";
+        ObjectMapper objectMapper = new ObjectMapper();
+        GeojsonGeometry geometry = objectMapper.readValue(point, GeojsonGeometry.class);
+        assertThat(geometry.getOdkCoordinates(), is("102 0.5 0 0"));
+    }
+
+    @Test
+    public void getOdkCoordinates_throwsException_ifGeometryNotPoint() throws IOException {
+        String notPoint = "{\n" +
+            "               \"type\": \"LineString\",\n" +
+            "               \"coordinates\": [102.0, 0.0]\n" +
+            "           }";
+        ObjectMapper objectMapper = new ObjectMapper();
+        GeojsonGeometry geometry = objectMapper.readValue(notPoint, GeojsonGeometry.class);
+
+        try {
+            geometry.getOdkCoordinates();
+            fail("Exception expected");
+        } catch (UnsupportedOperationException e) {
+            // expected
+        }
+    }
+
+    private static final String GEOMETRY_COLLECTION_GEOJSON = "{\n" +
+        "    \"geometries\": [\n" +
+        "        {\n" +
+        "            \"coordinates\": [\n" +
+        "                [\n" +
+        "                    10.0,\n" +
+        "                    11.2\n" +
+        "                ],\n" +
+        "                [\n" +
+        "                    10.5,\n" +
+        "                    11.9\n" +
+        "                ]\n" +
+        "            ],\n" +
+        "            \"type\": \"Linestring\"\n" +
+        "        },\n" +
+        "        {\n" +
+        "            \"coordinates\": [\n" +
+        "                10.0,\n" +
+        "                20.0\n" +
+        "            ],\n" +
+        "            \"type\": \"Point\"\n" +
+        "        }\n" +
+        "    ],\n" +
+        "    \"type\": \"GeometryCollection\"\n" +
+        "}";
+
+    private static final String FEATURE_COLLECTION_GEOJSON = "{\n" +
+        "    \"type\": \"FeatureCollection\",\n" +
+        "    \"features\": [\n" +
+        "        {\n" +
+        "            \"type\": \"Feature\",\n" +
+        "            \"geometry\": {\n" +
+        "                \"type\": \"Point\",\n" +
+        "                \"coordinates\": [\n" +
+        "                    102,\n" +
+        "                    0.5\n" +
+        "                ]\n" +
+        "            },\n" +
+        "            \"properties\": {\n" +
+        "                \"id\": \"fs87b\",\n" +
+        "                \"name\": \"My cool point\",\n" +
+        "                \"foo\": \"bar\"\n" +
+        "            }\n" +
+        "        },\n" +
+        "        {\n" +
+        "            \"type\": \"Feature\",\n" +
+        "            \"geometry\": {\n" +
+        "                \"type\": \"Point\",\n" +
+        "                \"coordinates\": [\n" +
+        "                    104,\n" +
+        "                    0.5\n" +
+        "                ]\n" +
+        "            },\n" +
+        "            \"properties\": {\n" +
+        "                \"id\": \"67abie\",\n" +
+        "                \"name\": \"Your cool point\",\n" +
+        "                \"foo\": \"quux\",\n" +
+        "                \"special-property\": \"special value\"\n" +
+        "            }\n" +
+        "        }\n" +
+        "    ]\n" +
+        "}";
+}

src/test/java/org/javarosa/core/util/GeoUtilsTest.java

@@ -16,16 +16,15 @@
 
 package org.javarosa.core.util;
 
+import static org.javarosa.core.util.GeoUtils.EARTH_EQUATORIAL_CIRCUMFERENCE_METERS;
+import static org.junit.Assert.assertEquals;
+
 import java.util.ArrayList;
 import java.util.List;
-
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import static org.javarosa.core.util.GeoUtils.EARTH_EQUATORIAL_CIRCUMFERENCE_METERS;
-import static org.junit.Assert.assertEquals;
-
 /**
  * Tests features of GeoUtils. The tests whose names start with areaAndDistanceAreCorrectForPath
  * use data from www.mapdevelopers.com/area_finder.php. They test that the enclosed area,