added first version of rest api for tags

src/org/vitrivr/cineast/api/rest/RestfulAPI.java

@@ -10,6 +10,7 @@
 import org.vitrivr.cineast.api.rest.handlers.actions.FindSegmentAllByObjectIdActionHandler;
 import org.vitrivr.cineast.api.rest.handlers.actions.FindSegmentSimilarActionHandler;
 import org.vitrivr.cineast.api.rest.handlers.actions.FindSegmentsByIdActionHandler;
+import org.vitrivr.cineast.api.rest.handlers.actions.FindTagsByActionHandler;
 import org.vitrivr.cineast.api.rest.handlers.actions.StatusInvokationHandler;
 import org.vitrivr.cineast.api.rest.handlers.actions.session.EndSessionHandler;
 import org.vitrivr.cineast.api.rest.handlers.actions.session.StartSessionHandler;
@@ -153,12 +154,15 @@ public static void start() { //TODO check if already running
         http.get("/objects/all/:type", new FindObjectAllActionHandler());
 
         http.get("/segments/all/object/:id", new FindSegmentAllByObjectIdActionHandler());
+
+        http.get("/tags/by/:attribute/:value", new FindTagsByActionHandler(false));
 
         http.post("/segments/similar", new FindSegmentSimilarActionHandler());
 
         http.post("/segments/by/id", new FindSegmentsByIdActionHandler());
         http.post("/objects/by/id", new FindObjectsByIdActionHandler());
         http.post("/metas/by/id", new FindMetadatasByIdActionHandler());
+        http.post("/tags/by/id", new FindTagsByActionHandler(true));
       });
 
       http.path(makePath("session"), () -> {

src/org/vitrivr/cineast/api/rest/handlers/actions/FindTagsByActionHandler.java

@@ -0,0 +1,72 @@
+package org.vitrivr.cineast.api.rest.handlers.actions;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Map;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.vitrivr.cineast.api.rest.exceptions.ActionHandlerException;
+import org.vitrivr.cineast.api.rest.handlers.abstracts.ParsingActionHandler;
+import org.vitrivr.cineast.core.data.entities.Tag;
+import org.vitrivr.cineast.core.data.messages.lookup.IdList;
+import org.vitrivr.cineast.core.db.dao.TagHandler;
+
+public class FindTagsByActionHandler extends ParsingActionHandler<IdList> {
+
+  private static TagHandler tagHandler = new TagHandler();
+  private static final Logger LOGGER = LogManager.getLogger();
+
+
+  private static final  String ATTRIBUTE_NAME = ":attribute";
+  private static final String VALUE_NAME = ":value";
+
+
+
+  private final boolean post;
+
+  public FindTagsByActionHandler(boolean post){
+    this.post = post;
+  }
+
+  @Override
+  public Object invoke(IdList context, Map<String, String> parameters)
+      throws ActionHandlerException {
+
+    if(post){
+
+      if(context == null || context.getIds().length == 0){
+        return Collections.emptyList();
+      }
+
+      return tagHandler.getTagsById(context.getIds());
+
+    }else{
+      String attribute = parameters.get(ATTRIBUTE_NAME);
+      String value = parameters.get(VALUE_NAME);
+
+      ArrayList<Tag> list = new ArrayList<>();
+
+      switch(attribute.toLowerCase()){
+      case "id":{
+        list.add(tagHandler.getTagById(value));
+        break;
+      }
+      case "name":{
+        list.addAll(tagHandler.getTagsByName(value));
+        break;
+      }
+      default:{
+        LOGGER.error("Unknown attribute '{}' in FindTagsByActionHandler", attribute);
+      }
+      }
+      return list;
+    }
+  }
+
+  @Override
+  public Class<IdList> inClass() {
+    return IdList.class;
+  }
+
+}

src/org/vitrivr/cineast/core/db/dao/TagHandler.java

@@ -76,6 +76,25 @@ public Tag getTagById(String id) {
     return fromMap(rows.get(0));
 
   }
+
+  public List<Tag> getTagsById(String... ids) {
+    if (ids == null) {
+      return null;
+    }
+    List<Map<String, PrimitiveTypeProvider>> rows = this.selector.getRows("id", ids);
+    if (rows.isEmpty()) {
+      return null;
+    }
+    ArrayList<Tag> _return = new ArrayList<>(rows.size());
+    for (Map<String, PrimitiveTypeProvider> row : rows) {
+      Tag t = fromMap(row);
+      if (t != null) {
+        _return.add(t);
+      }
+    }
+    return _return;
+
+  }
 
   public List<Tag> getAll() {
     return this.selector.getAll().stream().map(TagHandler::fromMap).filter(Objects::nonNull)