org.apache.lucene.document.Document Maven / Gradle / Ivy
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/*
* 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.lucene.document;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.index.StoredFields; // for javadoc
import org.apache.lucene.search.ScoreDoc; // for javadoc
import org.apache.lucene.util.BytesRef;
/**
* Documents are the unit of indexing and search.
*
* A Document is a set of fields. Each field has a name and a textual value. A field may be
* {@link org.apache.lucene.index.IndexableFieldType#stored() stored} with the document, in which
* case it is returned with search hits on the document. Thus each document should typically contain
* one or more stored fields which uniquely identify it.
*
*
Note that fields which are not {@link
* org.apache.lucene.index.IndexableFieldType#stored() stored} are not available in documents
* retrieved from the index, e.g. with {@link ScoreDoc#doc} or {@link StoredFields#document(int)}.
*/
public final class Document implements Iterable {
private final List fields = new ArrayList<>();
/** Constructs a new document with no fields. */
public Document() {}
@Override
public Iterator iterator() {
return fields.iterator();
}
/**
* Adds a field to a document. Several fields may be added with the same name. In this case, if
* the fields are indexed, their text is treated as though appended for the purposes of search.
*
* Note that add like the removeField(s) methods only makes sense prior to adding a document to
* an index. These methods cannot be used to change the content of an existing index! In order to
* achieve this, a document has to be deleted from an index and a new changed version of that
* document has to be added.
*/
public final void add(IndexableField field) {
fields.add(field);
}
/**
* Removes field with the specified name from the document. If multiple fields exist with this
* name, this method removes the first field that has been added. If there is no field with the
* specified name, the document remains unchanged.
*
*
Note that the removeField(s) methods like the add method only make sense prior to adding a
* document to an index. These methods cannot be used to change the content of an existing index!
* In order to achieve this, a document has to be deleted from an index and a new changed version
* of that document has to be added.
*/
public final void removeField(String name) {
Iterator it = fields.iterator();
while (it.hasNext()) {
IndexableField field = it.next();
if (field.name().equals(name)) {
it.remove();
return;
}
}
}
/**
* Removes all fields with the given name from the document. If there is no field with the
* specified name, the document remains unchanged.
*
* Note that the removeField(s) methods like the add method only make sense prior to adding a
* document to an index. These methods cannot be used to change the content of an existing index!
* In order to achieve this, a document has to be deleted from an index and a new changed version
* of that document has to be added.
*/
public final void removeFields(String name) {
Iterator it = fields.iterator();
while (it.hasNext()) {
IndexableField field = it.next();
if (field.name().equals(name)) {
it.remove();
}
}
}
/**
* Returns an array of byte arrays for of the fields that have the name specified as the method
* parameter. This method returns an empty array when there are no matching fields. It never
* returns null.
*
* @param name the name of the field
* @return a BytesRef[] of binary field values
*/
public final BytesRef[] getBinaryValues(String name) {
final List result = new ArrayList<>();
for (IndexableField field : fields) {
if (field.name().equals(name)) {
final BytesRef bytes = field.binaryValue();
if (bytes != null) {
result.add(bytes);
}
}
}
return result.toArray(new BytesRef[result.size()]);
}
/**
* Returns an array of bytes for the first (or only) field that has the name specified as the
* method parameter. This method will return null if no binary fields with the
* specified name are available. There may be non-binary fields with the same name.
*
* @param name the name of the field.
* @return a BytesRef containing the binary field value or null
*/
public final BytesRef getBinaryValue(String name) {
for (IndexableField field : fields) {
if (field.name().equals(name)) {
final BytesRef bytes = field.binaryValue();
if (bytes != null) {
return bytes;
}
}
}
return null;
}
/**
* Returns a field with the given name if any exist in this document, or null. If multiple fields
* exists with this name, this method returns the first value added.
*/
public final IndexableField getField(String name) {
for (IndexableField field : fields) {
if (field.name().equals(name)) {
return field;
}
}
return null;
}
/**
* Returns an array of {@link IndexableField}s with the given name. This method returns an empty
* array when there are no matching fields. It never returns null.
*
* @param name the name of the field
* @return a Field[] array
*/
public IndexableField[] getFields(String name) {
List result = new ArrayList<>();
for (IndexableField field : fields) {
if (field.name().equals(name)) {
result.add(field);
}
}
return result.toArray(new IndexableField[result.size()]);
}
/**
* Returns a List of all the fields in a document.
*
* Note that fields which are not stored are not available in documents retrieved
* from the index, e.g. {@link StoredFields#document(int)}.
*
* @return an immutable List<Field>
*/
public final List getFields() {
return Collections.unmodifiableList(fields);
}
private static final String[] NO_STRINGS = new String[0];
/**
* Returns an array of values of the field specified as the method parameter. This method returns
* an empty array when there are no matching fields. It never returns null. For a numeric {@link
* StoredField} it returns the string value of the number. If you want the actual numeric field
* instances back, use {@link #getFields}.
*
* @param name the name of the field
* @return a String[] of field values
*/
public final String[] getValues(String name) {
List result = new ArrayList<>();
for (IndexableField field : fields) {
if (field.name().equals(name) && field.stringValue() != null) {
result.add(field.stringValue());
}
}
if (result.size() == 0) {
return NO_STRINGS;
}
return result.toArray(new String[result.size()]);
}
/**
* Returns the string value of the field with the given name if any exist in this document, or
* null. If multiple fields exist with this name, this method returns the first value added. If
* only binary fields with this name exist, returns null. For a numeric {@link StoredField} it
* returns the string value of the number. If you want the actual numeric field instance back, use
* {@link #getField}.
*/
public final String get(String name) {
for (IndexableField field : fields) {
if (field.name().equals(name) && field.stringValue() != null) {
return field.stringValue();
}
}
return null;
}
/** Prints the fields of a document for human consumption. */
@Override
public final String toString() {
StringBuilder buffer = new StringBuilder();
buffer.append("Document<");
for (int i = 0; i < fields.size(); i++) {
IndexableField field = fields.get(i);
buffer.append(field.toString());
if (i != fields.size() - 1) {
buffer.append(" ");
}
}
buffer.append(">");
return buffer.toString();
}
/** Removes all the fields from document. */
public void clear() {
fields.clear();
}
}