/*
* Copyright 2013 NGDATA nv
*
* 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.
*/
package org.lilyproject.tools.import_.json;
import org.joda.time.DateTime;
import org.joda.time.LocalDate;
import org.lilyproject.repository.api.Link;
import org.lilyproject.repository.api.Record;
import org.lilyproject.repository.api.RepositoryException;
import java.math.BigDecimal;
import java.net.URI;
import java.util.List;
/**
* A specialized RecordReader which will drop fields containing empty strings, drop lists
* containing zero entries, and drop nested records containing zero fields.
* For fields in the root record, the fields are not just skipped, they are actively deleted
* by adding them to the deleted fields (this last part is actually a feature of the
* superclass, see {@link RecordReader#deleteNullFields()}).
*
* <p>This makes a lot of sense when the input jsons are generated by ETL jobs that don't
* want to bother with having to change the structure of the JSON according to whether
* a field has a value or not. Instead, they can use a fixed json structure into which
* they just need to fill in the blanks.</p>
*/
public class IgnoreEmptyFieldsRecordReader extends RecordReader {
public static final IgnoreEmptyFieldsRecordReader INSTANCE = new IgnoreEmptyFieldsRecordReader();
@Override
protected Record readNestedRecord(ValueHandle handle, ReadContext context)
throws InterruptedException, RepositoryException, JsonFormatException {
Record record = super.readNestedRecord(handle, context);
return record.getFields().isEmpty() ? null : record;
}
@Override
protected String readString(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readString(handle, context);
}
@Override
protected List<Object> readList(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
List<Object> result = super.readList(handle, context);
return result != null && result.isEmpty() ? null : result;
}
@Override
protected List<Object> readPath(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
List<Object> result = super.readPath(handle, context);
return result != null && result.isEmpty() ? null : result;
}
@Override
protected LocalDate readDate(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readDate(handle, context);
}
@Override
protected DateTime readDateTime(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readDateTime(handle, context);
}
@Override
protected Link readLink(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readLink(handle, context);
}
@Override
protected Integer readInteger(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readInteger(handle, context);
}
@Override
protected Long readLong(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readLong(handle, context);
}
@Override
protected Double readDouble(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readDouble(handle, context);
}
@Override
protected BigDecimal readDecimal(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readDecimal(handle, context);
}
@Override
protected Boolean readBoolean(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readBoolean(handle, context);
}
@Override
protected URI readUri(ValueHandle handle, ReadContext context)
throws JsonFormatException, RepositoryException, InterruptedException {
return isBlank(handle) ? null : super.readUri(handle, context);
}
protected boolean isBlank(ValueHandle handle) {
return handle.node.isTextual() && handle.node.getTextValue().isEmpty();
}
}