[
https://issues.apache.org/jira/browse/HAWQ-178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15131713#comment-15131713
]
ASF GitHub Bot commented on HAWQ-178:
-------------------------------------
Github user hornn commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/302#discussion_r51828041
--- Diff:
pxf/pxf-json/src/main/java/org/apache/hawq/pxf/plugins/json/JsonResolver.java
---
@@ -0,0 +1,255 @@
+package org.apache.hawq.pxf.plugins.json;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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.
+ */
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hawq.pxf.api.OneField;
+import org.apache.hawq.pxf.api.OneRow;
+import org.apache.hawq.pxf.api.ReadResolver;
+import org.apache.hawq.pxf.api.io.DataType;
+import org.apache.hawq.pxf.api.utilities.ColumnDescriptor;
+import org.apache.hawq.pxf.api.utilities.InputData;
+import org.apache.hawq.pxf.api.utilities.Plugin;
+import org.codehaus.jackson.JsonFactory;
+import org.codehaus.jackson.JsonNode;
+import org.codehaus.jackson.map.ObjectMapper;
+
+/**
+ * This JSON resolver for PXF will decode a given object from the {@link
JsonAccessor} into a row for HAWQ. It will
+ * decode this data into a JsonNode and walk the tree for each column. It
supports normal value mapping via projections
+ * and JSON array indexing.
+ */
+public class JsonResolver extends Plugin implements ReadResolver {
+
+ private static final Log LOG = LogFactory.getLog(JsonResolver.class);
+
+ private ArrayList<OneField> oneFieldList;
+ private ColumnDescriptorCache[] columnDescriptorCache;
+ private ObjectMapper mapper;
+
+ public JsonResolver(InputData inputData) throws Exception {
+ super(inputData);
+ oneFieldList = new ArrayList<OneField>();
+ mapper = new ObjectMapper(new JsonFactory());
+
+ // Pre-generate all column structure attributes concerning the
JSON to column value resolution.
+ columnDescriptorCache = new
ColumnDescriptorCache[inputData.getColumns()];
+ for (int i = 0; i < inputData.getColumns(); ++i) {
+ ColumnDescriptor cd = inputData.getColumn(i);
+ columnDescriptorCache[i] = new
ColumnDescriptorCache(cd);
+ }
+ }
+
+ @Override
+ public List<OneField> getFields(OneRow row) throws Exception {
+ oneFieldList.clear();
+
+ String jsonRecordAsText = row.getData().toString();
+
+ JsonNode root = decodeLineToJsonNode(jsonRecordAsText);
+
+ if (root == null) {
+ LOG.warn("Return null-fields row due to invalid JSON:"
+ jsonRecordAsText);
--- End diff --
another possible improvement: create a final list of null fields for the
case where the root is null, and immediately return that list here.
That will save us the iteration over the columns and checking for each one
if the root is null.
> Add JSON plugin support in code base
> ------------------------------------
>
> Key: HAWQ-178
> URL: https://issues.apache.org/jira/browse/HAWQ-178
> Project: Apache HAWQ
> Issue Type: New Feature
> Components: PXF
> Reporter: Goden Yao
> Assignee: Christian Tzolov
> Fix For: backlog
>
> Attachments: PXFJSONPluginforHAWQ2.0andPXF3.0.0.pdf,
> PXFJSONPluginforHAWQ2.0andPXF3.0.0v.2.pdf,
> PXFJSONPluginforHAWQ2.0andPXF3.0.0v.3.pdf
>
>
> JSON has been a popular format used in HDFS as well as in the community,
> there has been a few JSON PXF plugins developed by the community and we'd
> like to see it being incorporated into the code base as an optional package.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
