Develop Reference

Java, Vaadin 8, lazy loading with grid

I am trying to implement lazy loading with Grid in Vaadin 8. But it only shows an empty table. What do I do wrong? Also, how do I set the number of items to load (limit) to for example 20 items (the default is 40 items)?
private Grid<Image> makeLazyTable()
{
Grid<Image> grid = new Grid<Image>();
DataProvider<Image, Void> dataProvider = DataProvider.fromCallbacks(
query -> {
int offset = query.getOffset();
int limit = query.getLimit();
OffsetRequest request = new OffsetRequest();
request.setLimit(limit);
request.setOffset(offset);
List<QuerySortOrder> sort = query.getSortOrders();
return ImagesRepository.findAll(request, sort);
},
query -> ImagesRepository.getImageCount()
);
grid.setDataProvider(dataProvider);
return grid;
}

I did not add any columns. That was the reason why the table was empty.
This way it works:
Column<Image, String> filenameColumn = grid.addColumn(Image::getFilename);
Column<Image, String> orientationColumn = grid.addColumn(Image::getOrientation);
Column<Image, String> latitudeColumn = grid.addColumn(Image::getLatitude);
Column<Image, String> longitudeColumn = grid.addColumn(Image::getLongitude);

Inserting a row in Google spreadsheet: Blank rows cannot be written; use delete instead

I am unable to add row to an existing spreadsheet.
I'm trying the steps from here: https://developers.google.com/google-apps/spreadsheets/data
The following line throws the exception below:
row = service.insert(listFeedUrl, row);
Exception:
Exception in thread "main" com.google.gdata.util.InvalidEntryException: Bad Request
Blank rows cannot be written; use delete instead.
at com.google.gdata.client.http.HttpGDataRequest.handleErrorResponse(HttpGDataRequest.java:602)
at com.google.gdata.client.http.GoogleGDataRequest.handleErrorResponse(GoogleGDataRequest.java:564)
at com.google.gdata.client.http.HttpGDataRequest.checkResponse(HttpGDataRequest.java:560)
at com.google.gdata.client.http.HttpGDataRequest.execute(HttpGDataRequest.java:538)
at com.google.gdata.client.http.GoogleGDataRequest.execute(GoogleGDataRequest.java:536)
at com.google.gdata.client.Service.insert(Service.java:1409)
at com.google.gdata.client.GoogleService.insert(GoogleService.java:613)
at TestGoogle.main(TestGoogle.java:93)
The full story short: The above example is quite similar with the code in the application that I need to fix, and the application worked some times ago.
I managed to pass the OAuth2 authentication.

The reason you get this error message is probably because you're trying to add to a blank spreadsheet and the header doesn't exist.
If we add the headers first, then it should work.
Using the "Add a list row" example from the documentation you linked; add the headers like this before adding a list row
CellQuery cellQuery = new CellQuery(worksheet.CellFeedLink);
CellFeed cellFeed = service.Query(cellQuery);
CellEntry cellEntry = new CellEntry(1, 1, "firstname");
cellFeed.Insert(cellEntry);
cellEntry = new CellEntry(1, 2, "lastname");
cellFeed.Insert(cellEntry);
cellEntry = new CellEntry(1, 3, "age");
cellFeed.Insert(cellEntry);
cellEntry = new CellEntry(1, 4, "height");
cellFeed.Insert(cellEntry);
Then the list entry example should add to the spreadsheet properly
// Fetch the list feed of the worksheet.
ListQuery listQuery = new ListQuery(listFeedLink.HRef.ToString());
ListFeed listFeed = service.Query(listQuery);
// Create a local representation of the new row.
ListEntry row = new ListEntry();
row.Elements.Add(new ListEntry.Custom() { LocalName = "firstname", Value = "Joe" });
row.Elements.Add(new ListEntry.Custom() { LocalName = "lastname", Value = "Smith" });
row.Elements.Add(new ListEntry.Custom() { LocalName = "age", Value = "26" });
row.Elements.Add(new ListEntry.Custom() { LocalName = "height", Value = "176" });
// Send the new row to the API for insertion.
service.Insert(listFeed, row);

How to get timestamped versions of HBase cell

How do I return all timestamped versions of an HBase cell with the Get.setMaxVersions(10) method where 10 is an arbitrary number (could be something else like 20 or 5)? The following is a console main method that creates a table, inserts 10 random integers, and tries to retrieve all of them to print out.
public static void main(String[] args)
throws ZooKeeperConnectionException, MasterNotRunningException, IOException, InterruptedException {
final String HBASE_ZOOKEEPER_QUORUM_IP = "localhost.localdomain"; //set ip in hosts file
final String HBASE_ZOOKEEPER_PROPERTY_CLIENTPORT = "2181";
final String HBASE_MASTER = HBASE_ZOOKEEPER_QUORUM_IP + ":60010";
//identify a data cell with these properties
String tablename = "characters";
String row = "johnsmith";
String family = "capital";
String qualifier = "A";
//config
Configuration config = HBaseConfiguration.create();
config.clear();
config.set("hbase.zookeeper.quorum", HBASE_ZOOKEEPER_QUORUM_IP);
config.set("hbase.zookeeper.property.clientPort", HBASE_ZOOKEEPER_PROPERTY_CLIENTPORT);
config.set("hbase.master", HBASE_MASTER);
//admin
HBaseAdmin hba = new HBaseAdmin(config);
//create a table
HTableDescriptor descriptor = new HTableDescriptor(tablename);
descriptor.addFamily(new HColumnDescriptor(family));
hba.createTable(descriptor);
hba.close();
//get the table
HTable htable = new HTable(config, tablename);
//insert 10 different timestamps into 1 record
for(int i = 0; i < 10; i++) {
String value = Integer.toString(i);
Put put = new Put(Bytes.toBytes(row));
put.add(Bytes.toBytes(family), Bytes.toBytes(qualifier), System.currentTimeMillis(), Bytes.toBytes(value));
htable.put(put);
Thread.sleep(200); //make sure each timestamp is different
}
//get 10 timestamp versions of 1 record
final int MAX_VERSIONS = 10;
Get get = new Get(Bytes.toBytes(row));
get.setMaxVersions(MAX_VERSIONS);
Result result = htable.get(get);
byte[] value = result.getValue(Bytes.toBytes(family), Bytes.toBytes(qualifier)); // returns MAX_VERSIONS quantity of values
String output = Bytes.toString(value);
//show me what you got
System.out.println(output); //prints 9 instead of 0 through 9
}
The output is 9 (because the loop ended at i=9, and I don't see multiple versions in Hue's HBase Browser web UI. What can I do to fix the versions so it gives me 10 individual results for 0 - 9 instead of one result of only the number 9?

You should use getColumnCells on Result to get all versions (depending on MAX_VERSION_COUNT you have set in Get). getValue returns the latest value.
Sample Code:
List<Cell> values = result.getColumnCells(Bytes.toBytes(family), Bytes.toBytes(qualifier));
for ( Cell cell : values )
{
System.out.println( Bytes.toString( CellUtil.cloneValue( cell ) ) );
}

This is a deprecated approach which matches the version of HBase I am currently working on.
List<KeyValue> kvpairs = result.getColumn(Bytes.toBytes(family), Bytes.toBytes(qualifier));
String line = "";
for(KeyValue kv : kvpairs) {
line += Bytes.toString(kv.getValue()) + "\n";
}
System.out.println(line);
Then, going one step further, it is important to note the setMaxVersions method must be called at table creation to allow for more than a default three values to be inserted into a cell. Here's the updated table creation:
//create a table based on variables from question above
HTableDescriptor tableDescriptor = new HTableDescriptor(tablename);
HColumnDescriptor columnDescriptor = new HColumnDescriptor(columnFamily);
columnDescriptor.setMaxVersions(MAX_VERSIONS);
tableDescriptor.addFamily(columnDescriptor);
hba.createTable(tableDescriptor);
hba.close();

Dart Parse JSON into Table

I'm trying to figure out how to parse a JSON feed into a table in Dart. I'm not sure if I should use a Map but if I do, I'm not sure how to approach extracting data. I want to have one cell to hold the assetID, then another for domain name, and another for IP address. Please let me know if you need more information.
Dart:
void loadData()
{
var url = "http://localhost:8080/***selectAll";
//call the web server asynchronously
var request = HttpRequest.getString(url).then(onDataLoaded);
}
void onDataLoaded(String response)
{
TableElement table = querySelector("#domainTableSelector");
//table.children.add();
var jsonString = response;
// print(jsonString);
List<String> list = new List<String>();
list.add(jsonString);
for (var x = 0; x < list.length; x++)
{
//create new table row
TableRowElement row = table.insertRow(x+1);
TableCellElement cell = row.insertCell(x);
cell.text = list.toString();
// print(list);
}
// Iterator itr= list.iterator();
//
// print("Displaying List Elements,");
//
// while(itr.hasNext())
// {
// print(itr.next());
// }
}
JSON
[{"serviceResponseValue":[{"assetId":"8a41250446b89b5f0146b04d49910023","oplock":0,"longitude":115.86,"domainName":"free-aus-trip.au","latitude":-31.95,"ipAddress":"6.0.0.6"},{"assetId":"8a49859246918966014691b1aac9000c","oplock":0,"longitude":-65.30,"domainName":null,"latitude":-24.18,"ipAddress":"4.0.0.4"},{"assetId":"8a49859246876566014691b1437512e4","oplock":0,"longitude":77.60,"domainName":"allmovies.cn","latitude":12.97,"ipAddress":"14.0.0.14"},{"assetId":"8a49850446b04b5f0146b04d49910000","oplock":0,"longitude":112.47,"domainName":"getrichez.cn","latitude":32.98,"ipAddress":"5.0.0.5"},{"assetId":"8a498592469189660146919b7a210006","oplock":0,"longitude":-37.61,"domainName":"googles.com","latitude":55.75,"ipAddress":null},{"assetId":"8a42250876b89b5f0876b04d49910763","oplock":0,"longitude":-68.90,"domainName":"lolcatzfun.net","latitude":-22.48,"ipAddress":"8.0.0.8"},{"assetId":"8a498592469189660146919f8d700008","oplock":0,"longitude":113.50,"domainName":"ccn.com","latitude":52.03,"ipAddress":null},{"assetId":"8a45250446b89b5f0876b04d49910187","oplock":0,"longitude":115.84,"domainName":"free-aus-trip.au","latitude":-31.86,"ipAddress":"7.0.0.7"},{"assetId":"8a49859246918966014691aeda76000a","oplock":0,"longitude":3.38,"domainName":"cashnow.net","latitude":6.52,"ipAddress":"2.0.0.2"},{"assetId":"8a49859246918966014691ae19df0009","oplock":0,"longitude":7.48,"domainName":"free-money.tv","latitude":9.07,"ipAddress":"222.222.222.222"},{"assetId":"8a498592469189660146919e09900007","oplock":0,"longitude":30.34,"domainName":"facebok.com","latitude":59.93,"ipAddress":"111.111.111.222"},{"assetId":"8a49859246918966014691b14375000b","oplock":0,"longitude":116.41,"domainName":null,"latitude":39.90,"ipAddress":"0.0.0.111"}],"messages":{"messages":[]}}]

To work with JSON, you have in dart a great thing : dart:convert => JSON
here some example of use:
var encoded = JSON.encode([1, 2, { "a": null }]);
var decoded = JSON.decode('["foo", { "bar": 499 }]');
I have done some thing but i'm not sure that is fit perfectly with your need
import 'dart:html';
import 'dart:convert';
void loadData()
{
var url = "http://localhost:8080/***selectAll";
//call the web server asynchronously
var request = HttpRequest.getString(url).then(onDataLoaded);
}
void onDataLoaded(String response)
{
TableElement table = querySelector("#domainTableSelector");
//table.children.add();
var jsonString = response;
// print(jsonString);
var jsonObject = JSON.decode(jsonString);
for (var x = 0; x < jsonObject.length; x++)
{
//create new table row
TableRowElement row = table.insertRow(x+1);
for (var d in jsonObject[x]["serviceResponseValue"]) {
TableCellElement cell = row.insertCell(x);
cell.text = d["assetId"];
cell = row.insertCell(x);
cell.text = d["domainName"];
cell = row.insertCell(x);
cell.text = d["ipAddress"];
print(d["assetId"]);
print(d["domainName"]);
print(d["ipAddress"]);
}
// print(list);
}
}

You parse JSON into a Dart data structure using
import 'dart:convert' show JSON;
var decoded = JSON.decode(jsonString);
see also How to handle JSON in Dart (Alexandres answer)
decoded is then a Dart data structure (lists, maps, values) that you can iterate over or investigate in the debugger. If you need further assistance please add a comment.

Show cell data within listFilesInFolder Function

I have this formula, which successfully lists all of my files in a folder. Awesome. But, can I also, within this script list some specific cell data from each file?
function listFilesInFolder() {
var folder = DocsList.getFolder("1- Summaries");
var contents = folder.getFiles();
var file;
var data;
var sheet = SpreadsheetApp.getActiveSheet();
sheet.clear();
sheet.appendRow(["Name", "Date", "Size", "URL", "Download", "Description", "Type"]);
for (var i = 0; i < contents.length; i++) {
file = contents[i];
if (file.getFileType() == "SPREADSHEET") {
continue;
}
data = [
file.getName(),
file.getDateCreated(),
file.getValue(B10), **(THIS IS WHERE I WOULD LIKE TO GET DATA, but it does not work)**
file.getUrl(),
"https://docs.google.com/a/acme.com/spreadsheet/ccc?key=" + file.getId(),
file.getDescription(),
"audio/mp3"
]
sheet.appendRow(data);

You can read from the spreadsheet, yes.
In the place where if (file.getFileType()... is, put this:
var cellValue;
if (file.getFileType() === "SPREADSHEET") {
cellValue = SpreadsheetApp.openById(file.getId()).getSheetByName("NameOfSheet")
.getRange("B10").getValue();
} else {
cellValue = null; // specify some default value here!
}
...
Then in your data array:
data = [
file.getName(),
file.getDateCreated(),
cellValue,
...