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https://issues.apache.org/jira/browse/DRILL-7362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16921605#comment-16921605
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ASF GitHub Bot commented on DRILL-7362:
---------------------------------------
vvysotskyi commented on pull request #1849: DRILL-7362: COUNT(*) on JSON with
outer list results in JsonParse error
URL: https://github.com/apache/drill/pull/1849#discussion_r320351497
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/easy/json/reader/BaseJsonReader.java
##########
@@ -0,0 +1,161 @@
+/*
+ * 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.drill.exec.store.easy.json.reader;
+
+import com.fasterxml.jackson.core.JsonToken;
+import io.netty.buffer.DrillBuf;
+import org.apache.drill.common.exceptions.UserException;
+import org.apache.drill.exec.vector.complex.writer.BaseWriter.ComplexWriter;
+
+import java.io.IOException;
+
+/**
+ * Basic reader implementation for json documents.
+ */
+public abstract class BaseJsonReader extends BaseJsonProcessor {
+
+ private static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(BaseJsonReader.class);
+
+ /**
+ * Describes whether or not this reader can unwrap a single root array record
+ * and treat it like a set of distinct records.
+ */
+ private final boolean skipOuterList;
+
+ /**
+ * Whether the reader is currently in a situation where we are unwrapping an
+ * outer list.
+ */
+ private boolean inOuterList;
+
+ public BaseJsonReader(DrillBuf workBuf, boolean enableNanInf, boolean
enableEscapeAnyChar, boolean skipOuterList) {
+ super(workBuf, enableNanInf, enableEscapeAnyChar);
+ this.skipOuterList = skipOuterList;
+ }
+
+ @Override
+ public ReadState write(ComplexWriter writer) throws IOException {
+
+ ReadState readState = null;
+ try {
+ JsonToken t = lastSeenJsonToken;
+ if (t == null || t == JsonToken.END_OBJECT) {
+ t = parser.nextToken();
+ }
+ while (!parser.hasCurrentToken() && !parser.isClosed()) {
+ t = parser.nextToken();
+ }
+ lastSeenJsonToken = null;
+
+ if (parser.isClosed()) {
+ return ReadState.END_OF_STREAM;
+ }
+
+ readState = writeToVector(writer, t);
+
+ switch (readState) {
+ case END_OF_STREAM:
+ break;
+ case WRITE_SUCCEED:
+ break;
+ default:
+ throw getExceptionWithContext(UserException.dataReadError(),
null).message(
+ "Failure while reading JSON. (Got an invalid read state %s )",
readState.toString())
+ .build(logger);
+ }
+ } catch (com.fasterxml.jackson.core.JsonParseException ex) {
+ if (ignoreJSONParseError()) {
+ if (processJSONException() ==
JsonExceptionProcessingState.END_OF_STREAM) {
+ return ReadState.JSON_RECORD_PARSE_EOF_ERROR;
+ } else {
+ return ReadState.JSON_RECORD_PARSE_ERROR;
+ }
+ } else {
+ throw ex;
+ }
+ }
+ return readState;
+ }
+
+
+ private ReadState writeToVector(ComplexWriter writer, JsonToken t)
+ throws IOException {
+
+ switch (t) {
+ case START_OBJECT:
+ writeDocument(writer, t);
+ break;
+ case START_ARRAY:
+ if (inOuterList) {
+ throw createDocumentTopLevelException();
+ }
+
+ if (skipOuterList) {
+ t = parser.nextToken();
+ if (t == JsonToken.START_OBJECT) {
+ inOuterList = true;
+ writeDocument(writer, t);
+ } else {
+ throw createDocumentTopLevelException();
+ }
+
+ } else {
+ writeDocument(writer, t);
+ }
+ break;
+ case END_ARRAY:
+
+ if (inOuterList) {
+ confirmLast();
+ return ReadState.END_OF_STREAM;
+ } else {
+ throw getExceptionWithContext(UserException.dataReadError(),
null).message(
+ "Failure while parsing JSON. Ran across unexpected %s.",
JsonToken.END_ARRAY).build(logger);
+ }
+
+ case NOT_AVAILABLE:
+ return ReadState.END_OF_STREAM;
+ default:
+ throw getExceptionWithContext(UserException.dataReadError(), null)
+ .message(
+ "Failure while parsing JSON. Found token of [%s]. Drill
currently only supports parsing "
+ + "json strings that contain either lists or maps. The root
object cannot be a scalar.",
+ t).build(logger);
+ }
+
+ return ReadState.WRITE_SUCCEED;
+ }
+
+ protected abstract void writeDocument(ComplexWriter writer, JsonToken t)
throws IOException;
Review comment:
could you please add JavaDocs to these methods?
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> COUNT(*) on JSON with outer list results in JsonParse error
> -----------------------------------------------------------
>
> Key: DRILL-7362
> URL: https://issues.apache.org/jira/browse/DRILL-7362
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.16.0
> Reporter: Oleg Zinoviev
> Assignee: Oleg Zinoviev
> Priority: Major
> Fix For: 1.17.0
>
>
> Count from a JSON file with a outer array results in JsonParseException:
> Cannot read from the middle of a record. Current token was START_ARRAY.
> P.S. A simple select from such file works normally.
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