1 files changed, 169 insertions, 0 deletions
diff --git a/dcae-analytics/dcae-analytics-model/src/main/java/org/onap/dcae/analytics/model/util/function/JsonStringToMapFunction.java b/dcae-analytics/dcae-analytics-model/src/main/java/org/onap/dcae/analytics/model/util/function/JsonStringToMapFunction.java
new file mode 100644
index 0000000..a68c327
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+++ b/dcae-analytics/dcae-analytics-model/src/main/java/org/onap/dcae/analytics/model/util/function/JsonStringToMapFunction.java
@@ -0,0 +1,169 @@
+/*
+ * ================================================================================
+ * Copyright (c) 2018 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ *
+ */
+
+package org.onap.dcae.analytics.model.util.function;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+import org.onap.dcae.analytics.model.configbindingservice.ConfigBindingServiceConstants;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Converts JSON String to flatten map of key value pair
+ *
+ * @author Rajiv Singla
+ */
+public class JsonStringToMapFunction implements Function<String, Map<String, Object>> {
+
+    private static final Logger logger = LoggerFactory.getLogger(JsonStringToMapFunction.class);
+
+    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+    private final String keyPrefix;
+    private final String keySeparator;
+
+    public JsonStringToMapFunction(final String keyPrefix, final String keySeparator) {
+        this.keyPrefix = keyPrefix;
+        this.keySeparator = keySeparator;
+    }
+
+    public JsonStringToMapFunction(final String keyPrefix) {
+        this(keyPrefix, ConfigBindingServiceConstants.KEY_SEPARATOR);
+    }
+
+    public JsonStringToMapFunction() {
+        this("", ConfigBindingServiceConstants.KEY_SEPARATOR);
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public Map<String, Object> apply(final String jsonString) {
+
+        logger.debug("Converting JSON to flattened key value Map: {}", jsonString);
+        if (jsonString == null || jsonString.trim().isEmpty()) {
+            return new HashMap<>();
+        }
+
+        final Map<String, Object> result = flattenJson(jsonString);
+        logger.debug("Flattened Key Value Pairs");
+        result.forEach((key, value) -> logger.debug("{}:{}", key, value));
+        return result;
+    }
+
+    /**
+     * Flattens Json String
+     *
+     * @param jsonString json String
+     *
+     * @return map containing flattened json string key and value
+     */
+    private Map<String, Object> flattenJson(final String jsonString) {
+
+        try {
+            final JsonNode rootNode = OBJECT_MAPPER.readTree(jsonString);
+            final LinkedHashMap<String, Object> result = new LinkedHashMap<>();
+            flattenJsonNode(keyPrefix, rootNode, result);
+            return result;
+        } catch (IOException e) {
+            final String errorMessage = String.format("Unable to flatten JSON String to Map. Invalid JSON String: " +
+                    "%s", jsonString);
+            logger.error(errorMessage, e, jsonString);
+            throw new IllegalArgumentException(jsonString, e);
+        }
+
+    }
+
+    /**
+     * Flattens json array
+     *
+     * @param propertyPrefix property prefix
+     * @param jsonNodesIterator json array node that needs to be flattened
+     * @param resultMap result map containing flattened key value pairs
+     */
+    private void flattenJsonArray(String propertyPrefix, Iterator<JsonNode> jsonNodesIterator,
+                                  Map<String, Object> resultMap) {
+        int counter = 0;
+        while (jsonNodesIterator.hasNext()) {
+            flattenJsonNode(propertyPrefix + "[" + counter + "]", jsonNodesIterator.next(), resultMap);
+            counter++;
+        }
+
+    }
+
+    /**
+     * Flattens json array
+     *
+     * @param propertyPrefix property prefix
+     * @param objectNode json object node that needs to be flattened
+     * @param resultMap result map containing flattened key value pairs
+     */
+    private void flattenJsonMap(String propertyPrefix, JsonNode objectNode,
+                                Map<String, Object> resultMap) {
+        final Iterator<Map.Entry<String, JsonNode>> fieldsIterator = objectNode.fields();
+        while (fieldsIterator.hasNext()) {
+            final Map.Entry<String, JsonNode> fieldEntry = fieldsIterator.next();
+            final JsonNode jsonValue = fieldEntry.getValue();
+            final String jsonKey = fieldEntry.getKey();
+            flattenJsonNode(
+                    (propertyPrefix.isEmpty() ? "" : propertyPrefix + keySeparator) + jsonKey,
+                    jsonValue, resultMap);
+        }
+    }
+
+    /**
+     * Checks various elements types of JSON Types and flattens them based on their type
+     *
+     * @param propertyPrefix property prefix
+     * @param currentJsonNode currentJsonNode that may need to be flattened
+     * @param resultMap result map containing flattened key value pairs
+     */
+    private void flattenJsonNode(final String propertyPrefix, final JsonNode currentJsonNode,
+                                 final Map<String, Object> resultMap) {
+
+
+        if (currentJsonNode.isObject()) {
+            flattenJsonMap(propertyPrefix, currentJsonNode, resultMap);
+        } else if (currentJsonNode.isArray()) {
+            flattenJsonArray(propertyPrefix, currentJsonNode.iterator(), resultMap);
+        } else {
+            resultMap.put(propertyPrefix, getObjectValue(currentJsonNode));
+        }
+    }
+
+    private static Object getObjectValue(final JsonNode jsonNode) {
+        if (jsonNode.isTextual()) {
+            return jsonNode.textValue();
+        } else if (jsonNode.isNumber()) {
+            return jsonNode.asLong();
+        } else if (jsonNode.isBoolean()) {
+            return jsonNode.asBoolean();
+        } else {
+            return jsonNode.asText();
+        }
+    }
+}
+