improve osmCreateFeature tag handling

manually squash of the following commits:
* 3c4c5b6
* a240374
* 42cc9fb
* 8b20332
* ff09be4
* ec431a3
* 7bc17e6
* d431854
* 7cba1d7
* 518151b

and a few additional changes:
* mention tag key escaping in docs
* add to changelog

fixes #40

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## current master
 
+* data extraction: escape tags with `@` characters ([#40](https://github.com/GIScience/ohsome-api/issues/40))
+
 ## 1.2.3
 
 ### Bug Fixes

docs/response-parameters.rst

@@ -11,6 +11,13 @@ Description of parameters that are present in every response.
 * ``attribution`` - copyrights and attribution
 * ``apiVersion`` - version of the ohsome API
 
+OSM Tags
+--------
+
+When requested, the result will contain OSM elements' tags as individual GeoJSON properties.
+
+.. note:: Any OSM tag with a key starting with the special `@` character (e.g.: `@osmId`), will be modified through the addition of another `@` at the start (the example would be changed to `@@osmId`).
+
 Aggregation Parameters
 ----------------------
 

src/main/lombok/org/heigit/ohsome/ohsomeapi/executor/DataRequestExecutor.java

@@ -83,12 +83,7 @@ public void extract() throws Exception {
     }
     TagTranslator tt = DbConnData.tagTranslator;
     String[] keys = requestParameters.getKeys();
-    int[] keysInt = new int[keys.length];
-    if (keys.length != 0) {
-      for (int i = 0; i < keys.length; i++) {
-        keysInt[i] = tt.getOSHDBTagKeyOf(keys[i]).toInt();
-      }
-    }
+    final Set<Integer> keysInt = ExecutionUtils.keysToKeysInt(keys, tt);
     ExecutionUtils exeUtils = new ExecutionUtils(processingData);
     inputProcessor.processPropertiesParam();
     inputProcessor.processIsUnclippedParam();

src/main/lombok/org/heigit/ohsome/ohsomeapi/executor/ElementsRequestExecutor.java

@@ -10,6 +10,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.Set;
 import java.util.SortedMap;
 import java.util.TreeMap;
 import java.util.stream.Collectors;
@@ -108,12 +109,7 @@ public static void extract(RequestResource requestResource, ElementsGeometry ele
     RequestParameters requestParameters = processingData.getRequestParameters();
     TagTranslator tt = DbConnData.tagTranslator;
     String[] keys = requestParameters.getKeys();
-    int[] keysInt = new int[keys.length];
-    if (keys.length != 0) {
-      for (int i = 0; i < keys.length; i++) {
-        keysInt[i] = tt.getOSHDBTagKeyOf(keys[i]).toInt();
-      }
-    }
+    final Set<Integer> keysInt = ExecutionUtils.keysToKeysInt(keys, tt);
     final MapReducer<Feature> preResult;
     ExecutionUtils exeUtils = new ExecutionUtils(processingData);
     preResult = mapRed.map(snapshot -> {

src/main/lombok/org/heigit/ohsome/ohsomeapi/executor/ExecutionUtils.java

@@ -8,6 +8,8 @@
 import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Streams;
 import com.opencsv.CSVWriter;
 import com.zaxxer.hikari.HikariDataSource;
 import java.io.ByteArrayOutputStream;
@@ -17,7 +19,9 @@
 import java.sql.SQLException;
 import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
+import java.util.Collections;
 import java.util.EnumSet;
+import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
@@ -408,29 +412,18 @@ public List<String[]> createCsvTopComments(String url, String text, String apiVe
 
   /** Creates the <code>Feature</code> objects in the OSM data response. */
   public org.wololo.geojson.Feature createOSMFeature(OSMEntity entity, Geometry geometry,
-      Map<String, Object> properties, int[] keysInt, boolean includeTags,
+      Map<String, Object> properties, Set<Integer> keysInt, boolean includeTags,
       boolean includeOSMMetadata, boolean isContributionsEndpoint, ElementsGeometry elemGeom,
       EnumSet<ContributionType> contributionTypes) {
     if (geometry.isEmpty() && !contributionTypes.contains(ContributionType.DELETION)) {
       // skip invalid geometries (e.g. ways with 0 nodes)
       return null;
     }
     if (includeTags) {
-      for (OSHDBTag oshdbTag : entity.getTags()) {
-        properties.put(String.valueOf(oshdbTag.getKey()), oshdbTag);
-      }
-    } else if (keysInt.length != 0) {
-      int[] tags = entity.getRawTags();
-      for (int i = 0; i < tags.length; i += 2) {
-        int tagKeyId = tags[i];
-        int tagValueId = tags[i + 1];
-        for (int key : keysInt) {
-          if (tagKeyId == key) {
-            properties.put(String.valueOf(tagKeyId), new OSHDBTag(tagKeyId, tagValueId));
-            break;
-          }
-        }
-      }
+      properties.put("@tags", Iterables.toArray(entity.getTags(), OSHDBTag.class));
+    } else if (!keysInt.isEmpty()) {
+      properties.put("@tags", Streams.stream(entity.getTags())
+          .filter(t -> keysInt.contains(t.getKey())).toArray(OSHDBTag[]::new));
     }
     if (includeOSMMetadata) {
       properties =
@@ -912,20 +905,15 @@ private void writeStreamResponse(ThreadLocal<JsonGenerator> outputJsonGen,
     try {
       threadPool.submit(() -> stream.parallel().map(data -> {
         // 0. resolve tags
-        Map<String, Object> tags = data.getProperties();
-        List<String> keysToDelete = new LinkedList<>();
-        List<OSMTag> tagsToAdd = new LinkedList<>();
-        for (Entry<String, Object> tag : tags.entrySet()) {
-          String key = tag.getKey();
-          if (key.charAt(0) != '@') {
-            keysToDelete.add(key);
-            tagsToAdd.add(tts.get().getOSMTagOf((OSHDBTag) tag.getValue()));
+        Map<String, Object> props = data.getProperties();
+        OSHDBTag[] tags = (OSHDBTag[]) props.remove("@tags");
+        if (tags != null) {
+          for (OSHDBTag tag : tags) {
+            OSMTag osmTag = tts.get().getOSMTagOf(tag);
+            String key = osmTag.getKey();
+            props.put(key.startsWith("@") ? "@" + key : key, osmTag.getValue());
           }
         }
-        tags.keySet().removeAll(keysToDelete);
-        for (OSMTag tag : tagsToAdd) {
-          tags.put(tag.getKey(), tag.getValue());
-        }
         // 1. convert features to geojson
         try {
           outputBuffers.get().reset();
@@ -1018,6 +1006,19 @@ private Map<String, Object> addAdditionalProperties(OSMEntity entity,
     return properties;
   }
 
+  static Set<Integer> keysToKeysInt(String[] keys, TagTranslator tt) {
+    final Set<Integer> keysInt;
+    if (keys.length != 0) {
+      keysInt = new HashSet<>(keys.length);
+      for (int i = 0; i < keys.length; i++) {
+        keysInt.add(tt.getOSHDBTagKeyOf(keys[i]).toInt());
+      }
+    } else {
+      keysInt = Collections.emptySet();
+    }
+    return keysInt;
+  }
+
   /** Enum type used in /ratio computation. */
   public enum MatchType {
     MATCHES1, MATCHES2, MATCHESBOTH, MATCHESNONE

src/main/lombok/org/heigit/ohsome/ohsomeapi/executor/FlatMapExecutor.java

@@ -30,7 +30,7 @@ public class FlatMapExecutor implements Serializable {
   private final Set<SimpleFeatureType> simpleFeatureTypes;
   private final boolean requiresGeometryTypeCheck;
   private final FilterExpression filterExpression;
-  private final int[] keysInt;
+  private final Set<Integer> keysInt;
   private final boolean includeTags;
   private final boolean includeOSMMetadata;
   private final ElementsGeometry elementsGeometry;
@@ -41,7 +41,7 @@ public FlatMapExecutor(boolean isContributionsLatestEndpoint, boolean isContribu
       ExecutionUtils exeUtils, boolean clipGeometries, String startTimestamp,
       InputProcessingUtils utils,
       Set<SimpleFeatureType> simpleFeatureTypes, boolean requiresGeometryTypeCheck,
-      FilterExpression filterExpression, int[] keysInt, boolean includeTags,
+      FilterExpression filterExpression, Set<Integer> keysInt, boolean includeTags,
       boolean includeOSMMetadata,
       ElementsGeometry elementsGeometry, String endTimestamp,
       boolean isContainingSimpleFeatureTypes) {