/*
* 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.*;
import org.apache.lucene.index.IndexReader; // for javadoc
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.search.IndexSearcher; // 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.
*
* <p>Note that fields which are <i>not</i> {@link org.apache.lucene.index.IndexableFieldType#stored() stored} are
* <i>not</i> available in documents retrieved from the index, e.g. with {@link
* ScoreDoc#doc} or {@link IndexReader#document(int)}.
*/
public final class Document implements Iterable<IndexableField> {
private final List<IndexableField> fields = new ArrayList<>();
/** Constructs a new document with no fields. */
public Document() {}
@Override
public Iterator<IndexableField> iterator() {
return fields.iterator();
}
/**
* <p>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.</p>
* <p> 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.</p>
*/
public final void add(IndexableField field) {
fields.add(field);
}
/**
* <p>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.</p>
* <p> 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.</p>
*/
public final void removeField(String name) {
Iterator<IndexableField> it = fields.iterator();
while (it.hasNext()) {
IndexableField field = it.next();
if (field.name().equals(name)) {
it.remove();
return;
}
}
}
/**
* <p>Removes all fields with the given name from the document.
* If there is no field with the specified name, the document remains unchanged.</p>
* <p> 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.</p>
*/
public final void removeFields(String name) {
Iterator<IndexableField> 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 <code>BytesRef[]</code> of binary field values
*/
public final BytesRef[] getBinaryValues(String name) {
final List<BytesRef> 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 <code>null</code>
* 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 <code>BytesRef</code> containing the binary field value or <code>null</code>
*/
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 <code>Field[]</code> array
*/
public IndexableField[] getFields(String name) {
List<IndexableField> 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.
* <p>Note that fields which are <i>not</i> stored are
* <i>not</i> available in documents retrieved from the
* index, e.g. {@link IndexSearcher#doc(int)} or {@link
* IndexReader#document(int)}.
*
* @return an immutable <code>List<Field></code>
*/
public final List<IndexableField> getFields() {
return Collections.unmodifiableList(fields);
}
private final static 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 <code>String[]</code> of field values
*/
public final String[] getValues(String name) {
List<String> 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();
}
}