PARQUET-367: "parquet-cat -j" doesn't show all records.

Added JsonRecordFormatter which formats SimpleRecords into an structure that can be used with ObjectMapper to create a valid json structure. Unit test included.

Author: sircodesalotOfTheRound

parquet-tools/src/main/java/org/apache/parquet/tools/command/CatCommand.java

@@ -24,12 +24,16 @@
 import org.apache.commons.cli.Option;
 import org.apache.commons.cli.OptionBuilder;
 import org.apache.commons.cli.Options;
+import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 
+import org.apache.parquet.hadoop.ParquetFileReader;
 import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.hadoop.metadata.ParquetMetadata;
 import org.apache.parquet.tools.Main;
 import org.apache.parquet.tools.read.SimpleReadSupport;
 import org.apache.parquet.tools.read.SimpleRecord;
+import org.apache.parquet.tools.json.JsonRecordFormatter;
 
 public class CatCommand extends ArgsOnlyCommand {
   public static final String[] USAGE = new String[] {
@@ -71,9 +75,12 @@ public void execute(CommandLine options) throws Exception {
     try {
       PrintWriter writer = new PrintWriter(Main.out, true);
       reader = ParquetReader.builder(new SimpleReadSupport(), new Path(input)).build();
+      ParquetMetadata metadata = ParquetFileReader.readFooter(new Configuration(), new Path(input));
+      JsonRecordFormatter.JsonGroupFormatter formatter = JsonRecordFormatter.fromSchema(metadata.getFileMetaData().getSchema());
+
       for (SimpleRecord value = reader.read(); value != null; value = reader.read()) {
         if (options.hasOption('j')) {
-          value.prettyPrintJson(writer);
+          writer.write(formatter.formatRecord(value));
         } else {
           value.prettyPrint(writer);
         }

parquet-tools/src/main/java/org/apache/parquet/tools/json/JsonRecordFormatter.java

@@ -0,0 +1,132 @@
+/*
+ * 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.
+ */
+
+package org.apache.parquet.tools.json;
+
+import org.apache.parquet.schema.GroupType;
+import org.apache.parquet.schema.MessageType;
+import org.apache.parquet.schema.Type;
+import org.apache.parquet.tools.read.SimpleRecord;
+import org.codehaus.jackson.map.ObjectMapper;
+
+import java.io.IOException;
+import java.util.*;
+
+public abstract class JsonRecordFormatter<T> {
+  private static final int SINGLE_VALUE = 0;
+
+  public static class JsonPrimitiveWriter extends JsonRecordFormatter<Object> {
+
+    public JsonPrimitiveWriter(Type primitiveType) {
+      super(primitiveType);
+    }
+
+    @Override
+    protected Object formatResults(List<Object> listOfValues) {
+      if (super.typeInfo.getRepetition() == Type.Repetition.REPEATED) {
+        return listOfValues;
+      } else {
+        return listOfValues.get(SINGLE_VALUE);
+      }
+    }
+  }
+
+  public static class JsonGroupFormatter extends JsonRecordFormatter<SimpleRecord> {
+    private final Map<String, JsonRecordFormatter> formatters;
+
+    public JsonGroupFormatter(GroupType schema) {
+      super(schema);
+
+      this.formatters = buildWriters(schema);
+    }
+
+    private Map<String, JsonRecordFormatter> buildWriters(GroupType groupSchema) {
+      Map<String, JsonRecordFormatter> writers = new LinkedHashMap<String, JsonRecordFormatter>();
+      for (Type type : groupSchema.getFields()) {
+        if (type.isPrimitive()) {
+          writers.put(type.getName(), new JsonPrimitiveWriter(type));
+        } else {
+          writers.put(type.getName(), new JsonGroupFormatter((GroupType) type));
+        }
+      }
+
+      return writers;
+    }
+
+    private Object add(SimpleRecord record) {
+      return formatEntries(collateEntries(record));
+    }
+
+    private Map<String, List<Object>> collateEntries(SimpleRecord record) {
+      Map<String, List<Object>> collatedEntries = new LinkedHashMap<String, List<Object>>();
+      for (SimpleRecord.NameValue value : record.getValues()) {
+        if (collatedEntries.containsKey(value.getName())) {
+          collatedEntries.get(value.getName()).add(value.getValue());
+        } else {
+          List<Object> newResultListForKey = new ArrayList<Object>();
+          newResultListForKey.add(value.getValue());
+          collatedEntries.put(value.getName(), newResultListForKey);
+        }
+      }
+
+      return collatedEntries;
+    }
+
+    private Object formatEntries(Map<String, List<Object>> entries) {
+      Map<String, Object> results = new LinkedHashMap<String, Object>();
+      for (Map.Entry<String, List<Object>> entry : entries.entrySet()) {
+        JsonRecordFormatter formatter = formatters.get(entry.getKey());
+        results.put(entry.getKey(), formatter.formatResults(entry.getValue()));
+      }
+
+      return results;
+    }
+
+    @Override
+    protected Object formatResults(List<SimpleRecord> values) {
+      if (super.typeInfo.getRepetition() == Type.Repetition.REPEATED) {
+        List<Object> results = new ArrayList<Object>();
+        for (SimpleRecord object : values) {
+          results.add(add(object));
+        }
+
+        return results;
+      } else {
+        return add(values.get(SINGLE_VALUE));
+      }
+    }
+
+    public String formatRecord(SimpleRecord value) throws IOException {
+      ObjectMapper mapper = new ObjectMapper();
+      return mapper.writeValueAsString(add(value));
+    }
+  }
+
+  protected final Type typeInfo;
+
+  protected JsonRecordFormatter(Type type) {
+    this.typeInfo = type;
+  }
+
+  protected abstract Object formatResults(List<T> values);
+
+  public static JsonGroupFormatter fromSchema(MessageType messageType) {
+    return new JsonGroupFormatter(messageType);
+  }
+}

parquet-tools/src/main/java/org/apache/parquet/tools/read/SimpleRecord.java

@@ -111,6 +111,7 @@ protected Object toJsonObject() {
     for (NameValue value : values) {
       result.put(value.getName(), toJsonValue(value.getValue()));
     }
+
     return result;
   }