Github user olegz commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1202#discussion_r88302396
--- Diff:
nifi-commons/nifi-schema-utils/src/main/java/org/apache/nifi/repository/schema/RecordSchema.java
---
@@ -0,0 +1,188 @@
+/*
+ * 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.nifi.repository.schema;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class RecordSchema {
+ private static final String FIELD_NAME = "Field Name";
+ private static final String FIELD_TYPE = "Field Type";
+ private static final String REPETITION = "Repetition";
+ private static final String SUBFIELDS = "SubFields";
+
+ private static final String STRING_TYPE = "String";
+ private static final String INT_TYPE = "Integer";
+ private static final String LONG_TYPE = "Long";
+ private static final String SUBFIELD_TYPE = "SubFieldList";
+
+ private final List<RecordField> fields;
+
+ public RecordSchema(final List<RecordField> fields) {
+ this.fields = fields;
+ }
+
+ public RecordSchema(final RecordField... fields) {
+ this(Arrays.asList(fields));
+ }
+
+ public List<RecordField> getFields() {
+ return fields;
+ }
+
+ public RecordField getField(final String fieldName) {
+ return fields.stream()
+ .filter(field -> field.getFieldName().equals(fieldName))
+ .findFirst()
+ .orElse(null);
+ }
+
+ public void writeTo(final OutputStream out) throws IOException {
+ try {
+ final DataOutputStream dos = (out instanceof DataOutputStream)
? (DataOutputStream) out : new DataOutputStream(out);
+
+ dos.writeInt(fields.size());
+ for (final RecordField field : fields) {
+ writeField(field, dos);
+ }
+ } catch (final IOException ioe) {
+ throw new IOException("Unable to write Record Schema to
stream", ioe);
+ }
+ }
+
+ private void writeField(final RecordField field, final
DataOutputStream dos) throws IOException {
+ dos.writeInt(4); // A field is made up of 4 "elements": Field
Name, Field Type, Field Repetition, Sub-Fields.
+
+ // For each of the elements, we write a String indicating the
Element Name, a String indicating the Element Type, and
+ // finally the Element data itself.
+ dos.writeUTF(FIELD_NAME);
+ dos.writeUTF(STRING_TYPE);
+ dos.writeUTF(field.getFieldName());
+
+ dos.writeUTF(FIELD_TYPE);
+ dos.writeUTF(STRING_TYPE);
+ dos.writeUTF(field.getFieldType().name());
+
+ dos.writeUTF(REPETITION);
+ dos.writeUTF(STRING_TYPE);
+ dos.writeUTF(field.getRepetition().name());
+
+ dos.writeUTF(SUBFIELDS);
+ dos.writeUTF(SUBFIELD_TYPE);
+ final List<RecordField> subFields = field.getSubFields();
+ dos.writeInt(subFields.size()); // SubField is encoded as number
of Sub-Fields followed by the fields themselves.
+ for (final RecordField subField : subFields) {
+ writeField(subField, dos);
+ }
+ }
+
+ public static RecordSchema readFrom(final InputStream in) throws
IOException {
+ try {
+ final DataInputStream dis = (in instanceof DataInputStream) ?
(DataInputStream) in : new DataInputStream(in);
+
+ final int numFields = dis.readInt();
+ final List<RecordField> fields = new ArrayList<>(numFields);
+
+ for (int i = 0; i < numFields; i++) {
+ final RecordField field = readField(dis);
+ fields.add(field);
+ }
+
+ return new RecordSchema(fields);
+ } catch (final IOException ioe) {
+ throw new IOException("Unable to read Record Schema from
stream", ioe);
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ private static RecordField readField(final DataInputStream dis) throws
IOException {
+ final Map<String, Object> schemaFieldMap = new HashMap<>();
+ final int numElementsToRead = dis.readInt();
+ for (int i = 0; i < numElementsToRead; i++) {
+ final String fieldName = dis.readUTF();
+ final String typeName = dis.readUTF();
+ Object fieldValue = null;
+
+ switch (typeName) {
+ case STRING_TYPE:
+ fieldValue = dis.readUTF();
+ break;
+ case INT_TYPE:
+ fieldValue = dis.readInt();
+ break;
+ case LONG_TYPE:
+ fieldValue = dis.readLong();
+ break;
+ case SUBFIELD_TYPE: {
+ final int numFields = dis.readInt();
+ final List<RecordField> subFields = new
ArrayList<>(numFields);
+ for (int j = 0; j < numFields; j++) {
+ subFields.add(readField(dis));
+ }
+ fieldValue = subFields;
+ break;
+ }
+ default: {
+ throw new IOException("Cannot read schema because the
schema definition contains a field named '"
+ + fieldName + "' with a Field Type of '" +
typeName + "', which is not a known Field Type");
+ }
+ }
+
+ schemaFieldMap.put(fieldName, fieldValue);
+ }
+
+ final String fieldName = (String) schemaFieldMap.get(FIELD_NAME);
+ final String fieldTypeName = (String)
schemaFieldMap.get(FIELD_TYPE);
+ final String repetitionName = (String)
schemaFieldMap.get(REPETITION);
+ List<RecordField> subFields = (List<RecordField>)
schemaFieldMap.get(SUBFIELDS);
+ if (subFields == null) {
+ subFields = Collections.emptyList();
+ }
+
+ final Repetition repetition = Repetition.valueOf(repetitionName);
+ if (FieldType.COMPLEX.name().equals(fieldTypeName)) {
+ return new ComplexRecordField(fieldName, repetition,
subFields);
+ } else if (FieldType.UNION.name().equals(fieldTypeName)) {
+ return new UnionRecordField(fieldName, repetition, subFields);
+ } else if (FieldType.MAP.name().equals(fieldTypeName)) {
+ if (subFields.size() != 2) {
+ throw new IOException("Found a Map that did not have a
'Key' field and a 'Value' field but instead had " + subFields.size() + "
fields: " + subFields);
--- End diff --
IMHO message is a bit confusing. I'd say "Field of type Map must only
contain 2 elements representing key/value. Was. . . ."
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
