/*
* Copyright (C) 2011 lightcouch.org
*
* 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.lightcouch;
import static java.lang.String.format;
import static org.lightcouch.CouchDbUtil.*;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.commons.codec.Charsets;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.lightcouch.DesignDocument.MapReduce;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
/**
* This class provides access to the <tt>View</tt> APIs.
*
* <h3>Usage Example:</h3>
* <pre>
* {@code
* List<Foo> list = dbClient.view("example/foo")
* .startKey("start-key")
* .endKey("end-key")
* .limit(10)
* .includeDocs(true)
* .query(Foo.class);
*
* // scalar values
* int count = dbClient.view("example/by_tag")
* .key("couchdb")
* .queryForInt();
*
* // pagination
* Page<Foo> page = dbClient.view("example/foo").queryPage(...);
* }
* </pre>
*
* @see CouchDbClientBase#view(String)
* @see ViewResult
* @since 0.0.2
* @author Ahmed Yehia
*/
public class View {
private static final Log log = LogFactory.getLog(CouchDbClient.class);
// paging param fields
private static final String START_KEY = "s_k";
private static final String START_KEY_DOC_ID = "s_k_d_i";
private static final String CURRENT_START_KEY = "c_k";
private static final String CURRENT_START_KEY_DOC_ID = "c_k_d_i";
private static final String CURRENT_KEYS = "c";
private static final String ACTION = "a";
private static final String NEXT = "n";
private static final String PREVIOUS = "p";
// temp views
private static final String TEMP_VIEWS_DIR = "temp-views";
private static final String MAP_JS = "map.js";
private static final String REDUCE_JS = "reduce.js";
// view fields
private String key;
private String startKey;
private String startKeyDocId;
private String endKey;
private String endKeyDocId;
private Integer limit;
private String stale;
private Boolean descending;
private Integer skip;
private Boolean group;
private Integer groupLevel;
private Boolean reduce;
private Boolean includeDocs;
private Boolean inclusiveEnd;
private Boolean updateSeq;
private CouchDbClientBase dbc;
private Gson gson;
private URIBuilder uriBuilder;
private String allDocsKeys; // bulk docs
private MapReduce mapRedtempViewM; // temp view
View(CouchDbClientBase dbc, String viewId) {
assertNotEmpty(viewId, "View id");
this.dbc = dbc;
this.gson = dbc.getGson();
String view = viewId;
if(viewId.contains("/")) {
String[] v = viewId.split("/");
view = String.format("_design/%s/_view/%s", v[0], v[1]);
}
this.uriBuilder = URIBuilder.buildUri(dbc.getDBUri()).path(view);
}
// Query options
/**
* Queries a view as an {@link InputStream}
* <p>The stream should be properly closed after usage, as to avoid connection leaks.
* @return The result as an {@link InputStream}.
*/
public InputStream queryForStream() {
URI uri = uriBuilder.build();
if(allDocsKeys != null) { // bulk docs
return getStream(dbc.post(uri, allDocsKeys));
}
if(mapRedtempViewM != null) { // temp view
return getStream(dbc.post(uri, gson.toJson(mapRedtempViewM)));
}
return dbc.get(uri);
}
/**
* Queries a view.
* @param <T> Object type T
* @param classOfT The class of type T
* @return The result of the view query as a {@code List<T> }
*/
public <T> List<T> query(Class<T> classOfT) {
InputStream instream = null;
try {
Reader reader = new InputStreamReader(instream = queryForStream(), Charsets.UTF_8);
JsonArray jsonArray = new JsonParser().parse(reader)
.getAsJsonObject().getAsJsonArray("rows");
List<T> list = new ArrayList<T>();
for (JsonElement jsonElem : jsonArray) {
JsonElement elem = jsonElem.getAsJsonObject();
if(Boolean.TRUE.equals(this.includeDocs)) {
elem = jsonElem.getAsJsonObject().get("doc");
}
T t = this.gson.fromJson(elem, classOfT);
list.add(t);
}
return list;
} finally {
close(instream);
}
}
/**
* Queries a view.
* @param <K> Object type K (key)
* @param <V> Object type V (value)
* @param classOfK The class of type K.
* @param classOfV The class of type V.
* @param classOfT The class of type T.
* @return The View result entries.
*/
public <K, V, T> ViewResult<K, V, T> queryView(Class<K> classOfK, Class<V> classOfV, Class<T> classOfT) {
InputStream instream = null;
try {
Reader reader = new InputStreamReader(instream = queryForStream(), Charsets.UTF_8);
JsonObject json = new JsonParser().parse(reader).getAsJsonObject();
ViewResult<K, V, T> vr = new ViewResult<K, V, T>();
vr.setTotalRows(getAsLong(json, "total_rows"));
vr.setOffset(getAsInt(json, "offset"));
vr.setUpdateSeq(getAsLong(json, "update_seq"));
JsonArray jsonArray = json.getAsJsonArray("rows");
if(jsonArray.size() == 0) { // validate available rows
throw new NoDocumentException("No result was returned by this view query.");
}
for (JsonElement e : jsonArray) {
ViewResult<K, V, T>.Rows row = vr.new Rows();
row.setId(JsonToObject(gson, e, "id", String.class));
row.setKey(JsonToObject(gson, e, "key", classOfK));
row.setValue(JsonToObject(gson, e, "value", classOfV));
if(Boolean.TRUE.equals(this.includeDocs)) {
row.setDoc(JsonToObject(gson, e, "doc", classOfT));
}
vr.getRows().add(row);
}
return vr;
} finally {
close(instream);
}
}
/**
* @return The result of the view as String.
*/
public String queryForString() {
return queryValue(String.class);
}
/**
* @return The result of the view as int.
*/
public int queryForInt() {
return queryValue(int.class);
}
/**
* @return The result of the view as long.
*/
public long queryForLong() {
return queryValue(long.class);
}
/**
* @return The result of the view as boolean.
*/
public boolean queryForBoolean() {
return queryValue(boolean.class);
}
/**
* Queries for scalar values. Internal use.
*/
private <V> V queryValue(Class<V> classOfV) {
InputStream instream = null;
try {
Reader reader = new InputStreamReader(instream = queryForStream(), Charsets.UTF_8);
JsonArray array = new JsonParser().parse(reader).
getAsJsonObject().get("rows").getAsJsonArray();
if(array.size() != 1) { // expect exactly 1 row
throw new NoDocumentException("Expecting exactly a single result of this view query, but was: " + array.size());
}
return JsonToObject(gson, array.get(0), "value", classOfV);
} finally {
close(instream);
}
}
/**
* Queries a view for pagination, returns a next or a previous page, this method
* figures out which page to return based on the given param that is generated by an
* earlier call to this method, quering the first page is done by passing a {@code null} param.
* @param <T> Object type T
* @param rowsPerPage The number of rows per page.
* @param param The request parameter to use to query a page, or {@code null} to return the first page.
* @param classOfT The class of type T.
* @return {@link Page}
*/
public <T> Page<T> queryPage(int rowsPerPage, String param, Class<T> classOfT) {
if(param == null) { // assume first page
return queryNextPage(rowsPerPage, null, null, null, null, classOfT);
}
String currentStartKey;
String currentStartKeyDocId;
String startKey;
String startKeyDocId;
String action;
try {
// extract fields from the returned HEXed JSON object
final JsonObject json = new JsonParser().parse(new String(Base64.decodeBase64(param.getBytes()))).getAsJsonObject();
if(log.isDebugEnabled()) {
log.debug("Paging Param Decoded = " + json);
}
final JsonObject jsonCurrent = json.getAsJsonObject(CURRENT_KEYS);
currentStartKey = jsonCurrent.get(CURRENT_START_KEY).getAsString();
currentStartKeyDocId = jsonCurrent.get(CURRENT_START_KEY_DOC_ID).getAsString();
startKey = json.get(START_KEY).getAsString();
startKeyDocId = json.get(START_KEY_DOC_ID).getAsString();
action = json.get(ACTION).getAsString();
} catch (Exception e) {
throw new CouchDbException("could not parse the given param!", e);
}
if(PREVIOUS.equals(action)) { // previous
return queryPreviousPage(rowsPerPage, currentStartKey, currentStartKeyDocId, startKey, startKeyDocId, classOfT);
} else { // next
return queryNextPage(rowsPerPage, currentStartKey, currentStartKeyDocId, startKey, startKeyDocId, classOfT);
}
}
/**
* @return The next page.
*/
private <T> Page<T> queryNextPage(int rowsPerPage, String currentStartKey,
String currentStartKeyDocId, String startKey, String startKeyDocId, Class<T> classOfT) {
// set view query params
limit(rowsPerPage + 1);
includeDocs(true);
if(startKey != null) {
startKey(startKey);
startKeyDocId(startKeyDocId);
}
// init page, query view
final Page<T> page = new Page<T>();
final List<T> pageList = new ArrayList<T>();
final ViewResult<String, String, T> vr = queryView(String.class, String.class, classOfT);
final List<ViewResult<String, String, T>.Rows> rows = vr.getRows();
final int resultRows = rows.size();
final int offset = vr.getOffset();
final long totalRows = vr.getTotalRows();
// holds page params
final JsonObject currentKeys = new JsonObject();
final JsonObject jsonNext = new JsonObject();
final JsonObject jsonPrev = new JsonObject();
currentKeys.addProperty(CURRENT_START_KEY, rows.get(0).getKey());
currentKeys.addProperty(CURRENT_START_KEY_DOC_ID, rows.get(0).getId());
for (int i = 0; i < resultRows; i++) {
// set keys for the next page
if (i == resultRows - 1) { // last element (i.e rowsPerPage + 1)
if(resultRows > rowsPerPage) { // if not last page
page.setHasNext(true);
jsonNext.addProperty(START_KEY, rows.get(i).getKey());
jsonNext.addProperty(START_KEY_DOC_ID, rows.get(i).getId());
jsonNext.add(CURRENT_KEYS, currentKeys);
jsonNext.addProperty(ACTION, NEXT);
page.setNextParam(Base64.encodeBase64URLSafeString(jsonNext.toString().getBytes()));
continue; // exclude
}
}
pageList.add(rows.get(i).getDoc());
}
// set keys for the previous page
if(offset != 0) { // if not first page
page.setHasPrevious(true);
jsonPrev.addProperty(START_KEY, currentStartKey);
jsonPrev.addProperty(START_KEY_DOC_ID, currentStartKeyDocId);
jsonPrev.add(CURRENT_KEYS, currentKeys);
jsonPrev.addProperty(ACTION, PREVIOUS);
page.setPreviousParam(Base64.encodeBase64URLSafeString(jsonPrev.toString().getBytes()));
}
// calculate paging display info
page.setResultList(pageList);
page.setTotalResults(totalRows);
page.setResultFrom(offset + 1);
final int resultTo = rowsPerPage > resultRows ? resultRows : rowsPerPage; // fix when rowsPerPage exceeds returned rows
page.setResultTo(offset + resultTo);
page.setPageNumber((int) Math.ceil(page.getResultFrom() / Double.valueOf(rowsPerPage)));
return page;
}
/**
* @return The previous page.
*/
private <T> Page<T> queryPreviousPage(int rowsPerPage, String currentStartKey,
String currentStartKeyDocId, String startKey, String startKeyDocId, Class<T> classOfT) {
// set view query params
limit(rowsPerPage + 1);
includeDocs(true);
descending(true); // read backward
startKey(currentStartKey);
startKeyDocId(currentStartKeyDocId);
// init page, query view
final Page<T> page = new Page<T>();
final List<T> pageList = new ArrayList<T>();
final ViewResult<String, String, T> vr = queryView(String.class, String.class, classOfT);
final List<ViewResult<String, String, T>.Rows> rows = vr.getRows();
final int resultRows = rows.size();
final int offset = vr.getOffset();
final long totalRows = vr.getTotalRows();
Collections.reverse(rows); // fix order
// holds page params
final JsonObject currentKeys = new JsonObject();
final JsonObject jsonNext = new JsonObject();
final JsonObject jsonPrev = new JsonObject();
currentKeys.addProperty(CURRENT_START_KEY, rows.get(0).getKey());
currentKeys.addProperty(CURRENT_START_KEY_DOC_ID, rows.get(0).getId());
for (int i = 0; i < resultRows; i++) {
// set keys for the next page
if (i == resultRows - 1) { // last element (i.e rowsPerPage + 1)
if(resultRows >= rowsPerPage) { // if not last page
page.setHasNext(true);
jsonNext.addProperty(START_KEY, rows.get(i).getKey());
jsonNext.addProperty(START_KEY_DOC_ID, rows.get(i).getId());
jsonNext.add(CURRENT_KEYS, currentKeys);
jsonNext.addProperty(ACTION, NEXT);
page.setNextParam(Base64.encodeBase64URLSafeString(jsonNext.toString().getBytes()));
continue;
}
}
pageList.add(rows.get(i).getDoc());
}
// set keys for the previous page
if(offset != (totalRows - rowsPerPage - 1)) { // if not first page
page.setHasPrevious(true);
jsonPrev.addProperty(START_KEY, currentStartKey);
jsonPrev.addProperty(START_KEY_DOC_ID, currentStartKeyDocId);
jsonPrev.add(CURRENT_KEYS, currentKeys);
jsonPrev.addProperty(ACTION, PREVIOUS);
page.setPreviousParam(Base64.encodeBase64URLSafeString(jsonPrev.toString().getBytes()));
}
// calculate paging display info
page.setResultList(pageList);
page.setTotalResults(totalRows);
page.setResultFrom((int) totalRows - (offset + rowsPerPage));
final int resultTo = (int) totalRows - offset - 1;
page.setResultTo(resultTo);
page.setPageNumber(resultTo / rowsPerPage);
return page;
}
// fields
/**
* @param key The key value, accepts a single value or multiple values for complex keys.
*/
public View key(Object... key) {
this.key = getKeyAsJson(key);
uriBuilder.query("key", this.key);
return this;
}
/**
* @param startKey The start key value, accepts a single value or multiple values for complex keys.
*/
public View startKey(Object... startKey) {
this.startKey = getKeyAsJson(startKey);
uriBuilder.query("startkey", this.startKey);
return this;
}
public View startKeyDocId(String startKeyDocId) {
this.startKeyDocId = startKeyDocId;
uriBuilder.query("startkey_docid", this.startKeyDocId);
return this;
}
/**
* @param endKey The end key value, accepts a single value or multiple values for complex keys.
*/
public View endKey(Object... endKey) {
this.endKey = getKeyAsJson(endKey);
uriBuilder.query("endkey", this.endKey);
return this;
}
public View endKeyDocId(String endKeyDocId) {
this.endKeyDocId = endKeyDocId;
uriBuilder.query("endkey_docid", this.endKeyDocId);
return this;
}
public View limit(Integer limit) {
this.limit = limit;
uriBuilder.query("limit", this.limit);
return this;
}
/**
* @param stale Accept values: ok | update_after (update_after as of CouchDB 1.1.0)
*/
public View stale(String stale) {
this.stale = stale;
uriBuilder.query("stale", this.stale);
return this;
}
/**
* Reverses the reading direction, not the sort order.
*/
public View descending(Boolean descending) {
this.descending = Boolean.valueOf(gson.toJson(descending));
uriBuilder.query("descending", this.descending);
return this;
}
/**
* @param skip Skips <i>n</i> number of documents.
*/
public View skip(Integer skip) {
this.skip = skip;
uriBuilder.query("skip", this.skip);
return this;
}
/**
* @param group Specifies whether the reduce function reduces the result to a set of keys,
* or to a single result. Defaults to false (single result).
*/
public View group(Boolean group) {
this.group = group;
uriBuilder.query("group", this.group);
return this;
}
public View groupLevel(Integer groupLevel) {
this.groupLevel = groupLevel;
uriBuilder.query("group_level", this.groupLevel);
return this;
}
/**
* @param reduce Indicates whether to use the reduce function of the view,
* defaults to true if the reduce function is defined.
*/
public View reduce(Boolean reduce) {
this.reduce = reduce;
uriBuilder.query("reduce", this.reduce);
return this;
}
public View includeDocs(Boolean includeDocs) {
this.includeDocs = includeDocs;
uriBuilder.query("include_docs", this.includeDocs);
return this;
}
/**
* @param inclusiveEnd Indicates whether the endkey is included in the result,
* defaults to true.
*/
public View inclusiveEnd(Boolean inclusiveEnd) {
this.inclusiveEnd = inclusiveEnd;
uriBuilder.query("inclusive_end", this.inclusiveEnd);
return this;
}
public View updateSeq(Boolean updateSeq) {
this.updateSeq = updateSeq;
uriBuilder.query("update_seq", this.updateSeq);
return this;
}
/**
* Supplies a key list when calling <tt>_all_docs</tt> View.
* @param keys
* @return
*/
public View keys(List<?> keys) {
this.allDocsKeys = String.format("{%s:%s}", gson.toJson("keys"), gson.toJson(keys));
return this;
}
// temp views
public View tempView(String id) {
assertNotEmpty(id, "id");
String viewPath = format("%s/%s/", TEMP_VIEWS_DIR, id);
List<String> dirList = listResources(viewPath);
assertNotEmpty(dirList, "Temp view directory");
mapRedtempViewM = new MapReduce();
for (String mapRed : dirList) {
String def = readFile(format("/%s%s", viewPath, mapRed));
if(MAP_JS.equals(mapRed))
mapRedtempViewM.setMap(def);
else if(REDUCE_JS.equals(mapRed))
mapRedtempViewM.setReduce(def);
}
return this;
}
public View tempView(MapReduce mapReduce) {
assertNotEmpty(mapReduce, "mapReduce");
mapRedtempViewM = mapReduce;
return this;
}
private String getKeyAsJson(Object... key) {
return (key.length == 1) ? gson.toJson(key[0]) : gson.toJson(key); // single or complex key
}
}