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Problem to implement FindById to a return statement in java with MongoDB

UPDATE: The return statement is still not working as expected to show single user detail by id in the DAO. I could only use for loop to iterate through the _id to match the userId, but when I click the edit button for the number of user will show all previous user Id in the console.
Another problem is when I call this method in the Service class, the output is null. Still crave for the solution to help me get over it.
#Override
public User get(Object userId) {
User user = new User();
FindIterable<Document> userTbl = database.getCollection("User").find();
for (Document doc : userTbl) {
String id = doc.getObjectId("_id").toString();
System.out.println("_id = " + id);
if (id.equals(userId)) {
return user;
}
}
return null;
}
edit user in Service class
public void editUser() throws ServletException, IOException {
Object userId = request.getParameter("id"); // get query string from the jsp
User user = userDAO.get(userId);
System.out.println("User full name is? " + user.getFullName());
}

After getting hints from #Smutje and think through it again, finally figured it out at my 2nd weeks of learning MongoDB. At my level I need to iterate the user document then find the id and return it.it
#Override
public User get(Object userId) {
FindIterable<User> userTbl = database.getCollection("User", User.class).find();
for (User doc : userTbl) {
String id = doc.getId().toHexString();
System.out.println("_id = " + id);
if (id.equals(userId)) {
return doc;
}
}
return null;
}

Can't get results from flink SQL query

I'm facing a problem in which I don't get results from my query in Flink-SQL.
I have some informations stored in two Kafka Topics, I want to store them in two tables and perform a join between them in a streaming way.
These are my flink instructions :
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
StreamTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env);
// configure Kafka consumer
Properties props = new Properties();
props.setProperty("bootstrap.servers", "localhost:9092"); // Broker default host:port
props.setProperty("group.id", "flink-consumer"); // Consumer group ID
FlinkKafkaConsumer011<Blocks> flinkBlocksConsumer = new FlinkKafkaConsumer011<>(args[0], new BlocksSchema(), props);
flinkBlocksConsumer.setStartFromEarliest();
FlinkKafkaConsumer011<Transactions> flinkTransactionsConsumer = new FlinkKafkaConsumer011<>(args[1], new TransactionsSchema(), props);
flinkTransactionsConsumer.setStartFromEarliest();
DataStream<Blocks> blocks = env.addSource(flinkBlocksConsumer);
DataStream<Transactions> transactions = env.addSource(flinkTransactionsConsumer);
tableEnv.registerDataStream("blocksTable", blocks);
tableEnv.registerDataStream("transactionsTable", transactions);
Here is my SQL query :
Table sqlResult
= tableEnv.sqlQuery(
"SELECT block_timestamp,count(tx_hash) " +
"FROM blocksTable " +
"JOIN transactionsTable " +
"ON blocksTable.block_hash=transactionsTable.tx_hash " +
"GROUP BY blocksTable.block_timestamp");
DataStream<Test> resultStream = tableEnv
.toRetractStream(sqlResult,Row.class)
.map(t -> {
Row r = t.f1;
String field2 = r.getField(0).toString();
long count = Long.valueOf(r.getField(1).toString());
return new Test(field2,count);
})
.returns(Test.class);
Then, I print the results :
resultStream.print();
But I don't get any answers, my program is stuck...
For the schema used for serialization and deserialization, here is my test class which stores the result of my query (two fields a string and a long for respectively the block_timestamp and the count) :
public class TestSchema implements DeserializationSchema<Test>, SerializationSchema<Test> {
#Override
public Test deserialize(byte[] message) throws IOException {
return Test.fromString(new String(message));
}
#Override
public boolean isEndOfStream(Test nextElement) {
return false;
}
#Override
public byte[] serialize(Test element) {
return element.toString().getBytes();
}
#Override
public TypeInformation<Test> getProducedType() {
return TypeInformation.of(Test.class);
}
}
This is the same principle for BlockSchema and TransactionsSchema classes.
Do you know why I can't get the result of my query ? Should I test with BatchExecutionEnvironment ?

How to call a method that returns a list in another method and delete items in this list using iterator

Hey guys am new to this and I would appreciate any help.
I want to call getListTenant() from my save function below and clear the list using iterator before doing my save. Below is the code in my controller:
package controllers;
public class TenantController extends AppController {
Tenant tenant;
FacilityUnit unit;
// list tenants in selected facility
public Result listTenant() {
return ok(Json.toJson(getTenantList()));
}
private List<Tenant> getTenantList() {
List<Tenant> tenants = Tenant.find
.fetch("unit.facility")
.where().eq("unit.facility", currentFacility())
.findList();
return tenants;
}
public Result saveTenant() {
JsonNode submissionNode = request().body().asJson();
JsonNode itemsArray = submissionNode.get("items");
//clear tenant
// create the new tenant
if (itemsArray.isArray()) {
for (JsonNode itemNode : itemsArray) {
JsonNode tenantNode = itemNode.get("tenant");
String tenantId = tenantNode.get("id").asText();
JsonNode unitNode = itemNode.get("unit");
String unitId = unitNode.get("id").asText();
System.out.println("##### Tenant ID IS " + tenantId);
System.out.println("##### unit ID IS " + unitId);
// Tenant.find.where().eq("tenant.id",
// tenant.getTenant().getId()).eq("unit.id", unit.getId()
// ).delete();
// Util.isNotEmpty() &&
if (Util.isNotEmpty(tenantId) && Util.isNotEmpty(unitId)) {
// these two are the minimal criteria for an tenant
Tenant tenant = new Tenant();
tenant.setTenant(Person.find.byId(tenantId));
tenant.setUnit(FacilityUnit.find.byId(unitId));
tenant.save();
System.out.println("##### SAVED A TENANT");
}
}
}
System.out.println("##### DONE");
return ok(infoMessage("Update of " + tenant.getTenant() + "successful"));
}

Iterate over the Tenants from getTenantList() and call delete() on them to clear them.
For example:
private List<Tenant> getTenantList() {
List<Tenant> tenants = Tenant.find
.fetch("unit.facility")
.where().eq("unit.facility", currentFacility())
.findList();
return tenants;
}
public Result saveTenant() {
// Do something...
// ...
// Get the tenants list that we want to clear before saving.
// Best way to do this is loop over it and call delete.
for (Tenant tenant : getTenantList()) {
tenant.delete();
}
// Do some more things...
// ...
}

Can not fix "Unknown table" exception from JOOQ query

I am having trouble getting data from a database I know exists and I know the format of.
In the code snippet below the "if conn != null" is just a test to verify the database name, table name, etc are all correct, and they DO verify.
The last line below is what generates the exception
public static HashMap<Integer, String> getNetworkMapFromRemote(DSLContext dslRemote, Connection conn, Logger logger) {
HashMap<Integer,String> remoteMap = new HashMap<Integer, String>();
// conn is only used for test purposes
if (conn != null) {
// test to be sure database is ok
try
{
ResultSet rs = conn.createStatement().executeQuery("SELECT networkid, name FROM network");
while (rs.next()) {
System.out.println("TEST: nwid " + rs.getString(1) + " name " + rs.getString(2));
}
rs.close();
}
catch ( SQLException se )
{
logger.trace("getNetworksForDevices SqlException: " + se.toString());
}
}
// ----------- JOOQ problem section ------------------------
Network nR = Network.NETWORK.as("network");
// THE FOLLOWING LINE GENERATES THE UNKNOWN TABLE
Result<Record2<Integer, String>> result = dslRemote.select( nR.NETWORKID, nR.NAME ).fetch();
This is the output
TEST: nwid 1 name Network 1
org.jooq.exception.DataAccessException: SQL [select `network`.`NetworkId`, `network`.`Name` from dual]; Unknown table 'network' in field list
at org.jooq.impl.Utils.translate(Utils.java:1288)
at org.jooq.impl.DefaultExecuteContext.sqlException(DefaultExecuteContext.java:495)
at org.jooq.impl.AbstractQuery.execute(AbstractQuery.java:327)
at org.jooq.impl.AbstractResultQuery.fetch(AbstractResultQuery.java:330)
at org.jooq.impl.SelectImpl.fetch(SelectImpl.java:2256)
at com.nvi.kpiserver.remote.KpiCollectorUtil.getNetworkMapFromRemote(KpiCollectorUtil.java:328)
at com.nvi.kpiserver.remote.KpiCollectorUtilTest.testUpdateKpiNetworksForRemoteIntravue(KpiCollectorUtilTest.java:61)
.................
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown table 'network' in field list
.................
For the sake of completness here is part of the JOOQ generated class file for Network
package com.wbcnvi.intravue.generated.tables;
#javax.annotation.Generated(value = { "http://www.jooq.org", "3.3.1" },
comments = "This class is generated by jOOQ")
#java.lang.SuppressWarnings({ "all", "unchecked", "rawtypes" })
public class Network extends org.jooq.impl.TableImpl<com.wbcnvi.intravue.generated.tables.records.NetworkRecord> {
private static final long serialVersionUID = 1729023198;
public static final com.wbcnvi.intravue.generated.tables.Network NETWORK = new com.wbcnvi.intravue.generated.tables.Network();
#Override
public java.lang.Class<com.wbcnvi.intravue.generated.tables.records.NetworkRecord> getRecordType() {
return com.wbcnvi.intravue.generated.tables.records.NetworkRecord.class;
}
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.Integer> NWID = createField("NwId", org.jooq.impl.SQLDataType.INTEGER.nullable(false), this, "");
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.Integer> NETWORKID = createField("NetworkId", org.jooq.impl.SQLDataType.INTEGER.nullable(false).defaulted(true), this, "");
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.String> NAME = createField("Name", org.jooq.impl.SQLDataType.CHAR.length(40).nullable(false).defaulted(true), this, "");
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.Integer> USECOUNT = createField("UseCount", org.jooq.impl.SQLDataType.INTEGER.nullable(false).defaulted(true), this, "");
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.Integer> NETGROUP = createField("NetGroup", org.jooq.impl.SQLDataType.INTEGER.nullable(false).defaulted(true), this, "");
public final org.jooq.TableField<com.wbcnvi.intravue.generated.tables.records.NetworkRecord, java.lang.String> AGENT = createField("Agent", org.jooq.impl.SQLDataType.CHAR.length(16), this, "");
public Network() {
this("network", null);
}
public Network(java.lang.String alias) {
this(alias, com.wbcnvi.intravue.generated.tables.Network.NETWORK);
}
..........
Based on the "unknown table" exception I thought there was a problem connected to the wrong database or wrong server, but the console output is correct for a JDBC query.
Any thoughts are appreciated, perhaps something else can be the root cause or the DSLContext is not valid (but I would think that would generate a different exception).

The answer ends up being simple, I did not include the .from() method
Result<Record2<Integer, String>> result = dslRemote.select( nR.NETWORKID, nR.NAME )
.from(nR)
.fetch();
That is why the table was unknown, I never put the from method in.

Unable to set the value for running the java file

I'm working in Google gcm application,and here I'm authenticating the app user by correct Id & password.Authentication is working properly.
My I'm running this page by Run as -> Run on Server(Homeservlet.java),even for the correct employee and password,it's not showing the written jsp code(which is written in the if condition) and going to the else-part.
In the eclipse console : I can see the employee name and it's password.But my question is how to set the values sothat when I will run this page it'll show that jsp page inside.
I'm using set parameter to set the value,but whenever I'm running this page in Tomcat server,it's showing IllegalArgumentException.I found it's quiet relevant because when I'm running the value's are not set.
Actually I want ,for the correct employee and corresponding password,...it'll show that jsp page; otherwise(i mean in else-part,it'll not)
public class HomeServlet extends BaseServlet {
static final String ATTRIBUTE_STATUS = "status";
private static final int HTTP_STATUS = 200;
// private static final String HTTP = "OK";
protected void doGet(HttpServletRequest req, HttpServletResponse resp)throws IOException {
PreparedStatement stmt = null;
String employee=req.getParameter("employeeid"); //getting the value from app User
String password=req.getParameter("password"); //corresponding password
req.setAttribute(employee, employee);
req.setAttribute(password, password);
try {
String url="jdbc:mysql://localhost/apps";
Class.forName("com.mysql.jdbc.Driver");
Connection con=DriverManager.getConnection(url,"root","root");
stmt = con.prepareStatement("select * from regid where emp_id=? and password=?");
stmt.setString(1, employee);
stmt.setString(2, password);
ResultSet rs = stmt.executeQuery();
if(rs.next()) {
System.out.println("2> Employee Id : "+employee+" && Password : "+password);
System.out.println("3> This employee "+employee+" exsists in the database and will be there");
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.print("<html>"); //1> want to run this portion from here
out.print("<head>");
out.print("<title>Policy Page</title>");
out.print("<link rel='icon' href='../images/favicon.png'/>");
out.print("</head>");
out.print("<body>");
String status = (String) req.getAttribute(ATTRIBUTE_STATUS);
if (status != null)
{
out.print("Status : "+status);
}
List<String> devices = Datastore.getDevices();
if (devices.isEmpty())
{
out.print("<h2>No devices registered!</h2>");
}
else
{
out.print("<h2>" + devices.size() + " device(s) registered!</h2>");
out.print("<form name='form' method='POST' action='sendAll'>");
out.print("<input type='text' name='policy'>");
resp.setStatus(HttpServletResponse.SC_OK);
out.print("<input type='submit' value='Apply Policy'>");
out.print("</form>");
// getServletContext().getRequestDispatcher("/home").forward(req, resp);
}
out.print("</body></html>"); //2> to here
resp.setStatus(HttpServletResponse.SC_OK);
}
else { //else-part
resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
System.out.println(HttpServletResponse.SC_BAD_REQUEST);
System.out.println("4> This employee "+employee+" does not exsist in the database");
}
}
catch(Exception e) {
e.printStackTrace();
}
finally {
try {
stmt.close();
} catch(Exception x) {}
}
}
#Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
doGet(req, resp);
}
}
When the app user giving the id-password,the output in the console is:
2> Employee Id : P1 && Password : ppp
3> This employee P1 exsists in the database and will be there
but I'm running the page(run as->run on server-tomcat-6),it is showing this(instead of showing the jsp page)
HTTP Status 500
java.lang.IllegalArgumentException: Cannot call setAttribute with a null name
at org.apache.catalina.connector.Request.setAttribute(Request.java:1431)
at org.apache.catalina.connector.RequestFacade.setAttribute(RequestFacade.java:50
any idea....... where I'm going wrong.

2 things observed.
1)
Use
req.setParameter("employee", employee);
req.setParameter("password", password);
instead
req.setAttribute(employee, employee);
req.setAttribute(password, password);
2)
The next page you are showing is not a JSP. It is plain html created in servlet.
The set content type is html.
If you want to display employee in html,
you can write code like this,
out.print("<body>");
out.print("Welcome to this site Mr."+ employee);
If you still want to use the employee as a variable on that html, you have to embed Javascript in this page.