I think I found a bug in the last Jena (2.13).
If I call clear() on a DatasetGraph (instantiated with DatasetGraphFactory.createMem()) containing tuples of more than 1 graph, I get a ConcurrentModificationException.
You can reproduce the error with the following code:
public static void main(String[] args) {
DatasetGraph dsg = DatasetGraphFactory.createMem();
dsg.add(
new Quad(NodeFactory.createURI("http://graph1"),
NodeFactory.createURI("http://subj"),
RDF.type.asNode(),
NodeFactory.createURI("http://someType")));
dsg.add(
new Quad(NodeFactory.createURI("http://graph2"),
NodeFactory.createURI("http://subj"),
RDF.type.asNode(),
NodeFactory.createURI("http://someType")));
dsg.clear();
}
Is there a way to avoid this?
Best,
Flavio
The easiest fix is to replace dsg.clear with
dsg = DatasetGraphFactory.createMem() ;
and let the garbage collector deal with it. Or this:
dsg.getDefaultGraph().clear() ;
List<Node> graphNames = Iter.toList(dsg.listGraphNodes()) ;
for ( Node gn : graphNames ) {
dsg.removeGraph(gn);
}
Related
I'm working in report module, in order to do that I'm creating different stored procedures. I create the procedure with in parameters and then create a class to map the row (resultSet)
I think that's the best way to work arround performance and clarity.(what do you think about that?)
I'm using play framework and ebean orm (2.7.7)
I'm calling the store procedure and getting the resultSet, but I would like to use ebean in order to cast automaticly the row to model... other option is take the row-cell and cast it in a property but I'm trying to avoid it.
This is the current approach
Is this the best way to call an stored procedure?
Transaction tx = Ebean.beginTransaction();
String sql = "{CALL report(?, ?, ?, ?, ?, ?)}";
CallableStatement callableStatement = null;
try {
Connection dbConnection = tx.getConnection();
callableStatement = dbConnection.prepareCall(sql);
callableStatement.setInt(1, 3);
callableStatement.setInt(2, 5);
callableStatement.setInt(3, 2013);
callableStatement.setInt(4, 1);
callableStatement.setInt(5, 2014);
callableStatement.setInt(6, 5);
ResultSet rs = callableStatement.executeQuery(sql);
while (rs.next()) {
//HOW TO CONVER row -> model ?
}
Ebean.commitTransaction();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I've discarded RawSQL and Query because received an error
RuntimeException: Error parsing sql, can not find SELECT keyword in: xxxxx
Also I found other option... using CallableSql
String sql = "{call sp_order_mod(?,?)}";
CallableSql cs = Ebean.createCallableSql(sql);
cs.setParameter(1, "turbo");
cs.registerOut(2, Types.INTEGER);
Ebean.execute(cs);
// read the out parameter
Integer returnValue = (Integer) cs.getObject(2);
but in this case I need to return a ResultSet not simply parameter.
I'm going to share my own solution.
I get a class called ResultSetUtils.(you can google it some implementation)
I added a generic method in order to return a typed list from resultset
public static <T> List<T> populateInList(Class<T> c, final ResultSet rs) {
List<T> listTyped = new ArrayList<T>();
try {
if (rs != null) {
while (rs.next()) {
T o = c.newInstance();
// MAGIC LINE
populate(o, rs);
listTyped.add(o);
}
rs.close();
}
} catch (final Exception e) {
// TODO Auto-generated catch block
System.err.println(e.getMessage());
}
return listTyped;
}
This class to do the population use org.apache.commons.beanutils package
BeanUtils.populate(bean, propertiesRealName);
Using
private static void callingProcedureTest() {
Logger.debug("Init callingProcedureTest");
Transaction tx = Ebean.beginTransaction();
// String sql = "{CALL sp_report_test(3, 5, 2013, 1, 2014, 5)}";
String sql = "CALL sp_report_test(?, ?, ?, ?, ?, ?);";
try {
Connection dbConnection = tx.getConnection();
CallableStatement callableStatement = dbConnection.prepareCall(sql);
callableStatement.setInt(1, 3);
callableStatement.setInt(2, 5);
callableStatement.setInt(3, 2013);
callableStatement.setInt(4, 1);
callableStatement.setInt(5, 2014);
callableStatement.setInt(6, 5);
Logger.debug("SQL > " + sql);
ResultSet rs = callableStatement.executeQuery();
Class<ReportTestResult> c = ReportTestResult.class;
//************** MAGIC LINE, converting ResultSet to Model
List<ReportTestResult> listResult = ResultSetUtils.populateInList(c, rs);
for (ReportTestResult item : listResult) {
Logger.debug("item.firstName> " + item.firstName);
Logger.debug("item.lastName > " + item.lastName);
Logger.debug("item.year > " + item.year);
}
Ebean.commitTransaction();
} catch (Exception e) {
Ebean.rollbackTransaction();
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
Ebean.endTransaction();
}
}
Plus about architecture and implementation
For each report I'm going to create:
a Result class (eg ReportTestResult)
intention: represent a row of report | simple DTO
a Param class (eg ReportTestParam),
intention: represent the parameters (inputs / ouputs), filters of the report
This class should implements
public interface ReportParam {
public int countParameteres();
public void setParametersInCallableStatement(CallableStatement callableStatement) throws SQLException;
}
a Report class (eg ReportTestReport) this class should extends ReportBase
intention: Knows the stored procedure's name, parameters and dto result
public class ReportTestReport extends ReportBase<ReportTestResult, ReportTestParam> {
#Override
protected String getProcedureName() {
return STORED_NAME;
}
}
many Adapters...
Each report could displayed in different charts, In this case I'm using HighCharts. Order to arrange it, I'm creating different adapters to do that.
EG:
class ReportTestHighChartsAdapter
intention: convert a list of ReportTestResult to series and configure different options of report (eg, title, xAxis etc)
public OptionsHC buildColumnReportV1(){
OptionsHC optionChart = new OptionsHC();
optionChart.chart = new ChartHC("column");
this.setTitle(optionChart);
optionChart.yAxis = new AxisHC(new TitleHC("Fruit eaten"));
.....
return optionChart;
}
OptionsHC is a class that represent option obj in the HighCharts framework.
The final step is converting OptionHC to Json and use it in JavaScript (common use of highCharts)
What's ReportBase?
ReportBase class has the strategy to implements the final called to DB, also manage the transaction
public class ReportTestReport extends ReportBase<ReportTestResult, ReportTestParam> {
...
protected List<TResult> execute(Class<TResult> classT) {
List<TResult> resultDTO = null;
CallableStatement callableStatement = null;
Logger.debug("Running procedure> " + this.getProcedureName());
Transaction tx = Ebean.beginTransaction();
String sql = ProcedureBuilder.build(this.getProcedureName(), this.countParameters());
Logger.debug("SQL > " + sql);
try {
Connection dbConnection = tx.getConnection();
callableStatement = dbConnection.prepareCall(sql);
this.getFilter().setParametersInCallableStatement(callableStatement);
ResultSet rs = callableStatement.executeQuery();
resultDTO = ResultSetUtils.populateInList(classT, rs);
Ebean.commitTransaction();
Logger.debug("commitTransaction > " + sql);
} catch (Exception e) {
Ebean.rollbackTransaction();
Logger.debug("rollbackTransaction > " + sql);
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
Ebean.endTransaction();
}
return resultDTO;
}
...
}
Currently the support for stored procedures in Ebean is not orientated to what you are trying to do. Hence you are not going to get much joy from using CallableSql or RawSql.
>> a class to map the row (resultSet) I think that's the best way to work around performance and clarity
Yes, I can understand your motivation.
>> How to convert ResultSet into model
Currently there is no good solution. The best solution would be to enhance RawSql so that you can set a ResultSet onto it. One of the things RawSql does is provide the mapping of resultSet columns to model properties and that is what Ebean needs internally. The enhancement/code change would be to be able to set a resultSet onto the RawSql object ... and get Ebean internally to skip the creation of the resultSet ( preparedStatement, binding parameters and executeQuery()). In terms of Ebean internals this is all done in the CQuery.prepareBindExecuteQueryWithOption() method. That is, if the RawSql has already provided a resultSet skip those things.
The big benefit of doing this rather than just rolling your own row -> model mapping code is that the resulting beans would all still have lazy loading / partial object knowledge etc. They would behave exactly like any other beans that Ebean builds as part of it query mechanism.
So that said, I'm personally away for a week ... so you aren't going to hear back from me until after that. If you want to get into it yourself then internally CQuery.prepareBindExecuteQueryWithOption() is the code you will need to modify.
If you have been following the ebean google group you'll know that but just in case you have not been note that the Model and Finder objects from Play have been incorporated into Ebean just in the last week. This helps both projects ... reduces confusion etc. The Ebean source in github master is at 4.0.4 and the bytecode enhancement in 4.x is different and I don't believe supported in Play.
I'm basically going offline for a week now so I'll look back into this after that.
Cheers, Rob.
I have some piece of code that basically looks like this:
public MyObject getData(boolean someFlag) {
String select1 = "SELECT * FROM myTable WHERE someInteger = ?";
SqlHostvariablen hostvars = new SqlHostvara();
hostvars.addInteger(myField.getSomeInteger);
String[][] selarray = SqlHelper.doSelectAsMatrix(select1, hostvars);
if (selarray.length == 0) {
throw new IllegalArgumentException("Nothing found");
}
MyObject foo = new MyObject();
int i = 0;
foo.setSomething1(selarray[0][i++]);
foo.setSomething2(selarray[0][i++]);
foo.setSomething3(selarray[0][i++]);
foo.setSomething4(selarray[0][i++]);
foo.setSomething5(selarray[0][i++]);
foo.setSomething6(selarray[0][i++]);
foo.setSomething7(selarray[0][i++]);
foo.setSomething8(transformSomething8(selarray[0][i++]));
foo.setSomething9(selarray[0][i++]);
foo.setSomething10(selarray[0][i++]);
String someValue1 = selarray[0][i++];
String someValue2 = selarray[0][i++];
foo.setSomething11(selarray[0][i++]);
doSomethingWithFoo(foo, someFlag, someValue1, someValue2);
doSomethingElseWithFoo(foo);
return foo;
}
The identifiers and SQL statement are anonymized but otherwise my method looks the same.
Now Checkstyle claims that the cyclomatic comlexity if this method is 12. I always thought I knew what CC was and from my knowledge I'd say this methods CC is 2. There is one if that creates a new path through the code and the control flow graph therefore has 2 paths/exit points. I don't see where else there should be a path through the code.
Am I missing something entirely or is Checkstyle just wrong?
Turned out this was a Checkstyle error. While not even cleaning the problem did the trick, after a system restart the warning was gone. An Eclipse restart might have been enough, no way to know for sure.
I want to make several entries into a MySQL database. Because Some of the tables reference others via foreign key I have to get back the inserted ID to inject them in my next statements.
I have 4 classes:
LodgerFormTest
RentForm
RentObject
House
and the class which inserts the MySQL statements into the db: sql_statements
When I want to send a SQL statement I am getting a nullPointer Exception!
The Action listener of the House-class (this is the first sql-statement I have to send) looks like this:
saveButton.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
System.out.println("saveButton");
// sql_statements statements = new sql_statements();
sql_statements.performHouse(strasse.getText(), plz.getText(), ort.getText());
mainmenu.create();
rentnerFrame.dispose();
}
});
all methods and variables I am using in sql_statements are static! Therefore I am not instantiating an object.
here is the method "performHouse" in sql_statements
public static void performHouse(String strasse, String plz, String ort) {
String sql = "insert into haus(strasse, plz, ort) values (?,?,?)";
System.out.println(sql);
try{
ps = connect.prepareStatement(sql, ps.RETURN_GENERATED_KEYS);
ps.setString(1, strasse);
ps.setString(2, plz);
ps.setString(3, ort);
ps.execute();
rs = ps.getGeneratedKeys();
if(rs != null && rs.next()) {
// Retrieve the auto generated key(s).
key_idhaus = rs.getLong(1);
System.out.println("idhaus: " + key_idhaus);
}
}catch(Exception ex){
System.out.println(ex);
}
} // close performHouse-methode
I cant debug because I get a "Source not found." error in the debug view.
Can anybody help please?
okay I just wanted to finish the task so I implemented a solution which surely is all but not OO:
I implemented redundant code into all of the 4 classes and every class implements their own sql statements. quick and dirty ;)
I have the following code using a normal data context which works great:
var dc = new myDataContext();
Contract.Assume(dc.Cars!= null);
var cars = (from c in dc.Cars
where c.Owner == 'Jim'
select c).ToList();
However when I convert the filter to an extension method like this:
var dc = new myDataContext();
Contract.Assume(dc.Cars!= null);
var cars = dc.Cars.WithOwner('Jim');
public static IQueryable<Car> WithOwner(this IQueryable<Car> cars, string owner)
{
Contract.Requires(cars != null);
return cars.Where(c => c.Owner == owner);
}
I get the following warning:
warning : CodeContracts: requires unproven: source != null
My guess is that your warning is caused by the owner parameter, rather than the cars. Add a precondition in the WithOwner method to check if owner is not null.
public static IQueryable<Car> WithOwner(IQueryable<Car> cars, string owner)
{
Contract.Requires(cars != null);
Contract.Requires(!string.isNullOrEmpty(owner));
return cars.Where(c => c.Owner = owner);
}
In your first code sample, you have 'Jim' hard-coded, so no problems there because there is not something which can be null.
In your second example you created a method for which the static compiler cannot prove that the source ( being owner ) 'will never be null', as other code might call it with an invalid values.
I wonder how you get the code compiled with the Extension method since you are missing this keyword in your method signature.
public static IQueryable<Car> WithOwner(this IQueryable<Car> cars, string owner)
{
...
}
/KP
Its possible that your code snippet does not completely describe the code you are using.
Consider this snippet instead:
var dc = new myDataContext();
Contract.Assume(dc.Cars!= null);
var models = dc.Cars.WithOwner('Jim').Select(c => c.Model);
public static IQueryable<Car> WithOwner(this IQueryable<Car> cars, string owner)
{
Contract.Requires(cars != null);
return cars.Where(c => c.Owner == owner);
}
In this snipped its likely the runtime will complain with the warning you mentioned, but it is not complaining about Cars possibly being null, it is complaining about the result from WithOwner (passed into Select) possibly being null.
You can satisfy the runtime by ensuring that the result from your extension method will not be null:
Contract.Ensures(Contract.Result<IQueryable<Car>>() != null);
This contract should be ok because Where will not return null, but instead returns an Enumerable.Empty<T>() when there are no matches.
We fixed this a few releases back. The warning was due to some missing contracts around Linq expression construction etc. Linq expression methods have contracts and the C# compiler generates code that calls these methods. If we don't have enough post conditions on the called methods, then you can get these cryptic warnings about code that you don't even know is there (unless you look with ILdasm).
I have a Linq query that looks something like this:
var query = from x in table where SomeFunctionReturnsBool() select;
private bool SomeFunctionReturnsBool()
{
return true;
}
This returns and exception that says "SomeFunctionReturnsBool has no supported translation to SQL". I get that this is because it wants to treat "SomeFunctionReturnsBool" as an expression to evaluate as SQL, but it can't.
Although this Linq query isn't complicated, the real ones are. How can I accomplish what I'm trying to do here, which is to break out pieces of the query to hopefully make it more readable?
Jeff
UPDATE
Good answers. I am trying now to work with expressions instead, but this code gets me "cannot resolve method Where(lambda expression)":
var query = from x in table where SomeFunctionReturnsBool() select x;
private Expression<Func<EligibilityTempTable, bool>> SomeFunctionReturnsBool
{
return (x) => true;
}
Another way is to use Expression<Func<YourType, bool>> predicate...
var query = from x in table where SomeFunctionReturnsBool() select;
Edit: I don't usually do it the way I've shown above... I was just getting that from the code above. Here is the way I usually implement it. Because then you can tack on additional Enumerable methods or comment them out during debugging.
var results = table.Where(SomeFunctionReturnsBool())
.OrderBy(yt => yt.YourProperty)
//.Skip(pageCount * pageSize) //Just showing how you can easily comment out parts...
//.Take(pageSize)
.ToList(); //Finally executes the query...
private Expression<Func<YourType, boo>> SomeFunctionReturnsBool()
{
return (YourType yt) => yt.YourProperty.StartsWith("a")
&& yt.YourOtherProperty == true;
}
I prefer to use the PredicateBuilder which allows you to build an expression to be used in your Where...
You can do this in LINQ-to-SQL by creating a UDF mapped to the data-context; this involves writing TSQL, and use ctx.SomeFunctionblah(...).
The alternative is to work with expression trees - for example, it could be:
Expression<Func<Customer, bool>> SomeFunc() {
return c => true; // or whatever
}
and use .Where(SomeFunc()) - is that close enough? You can't use the query syntax in this case, but it gets the job done...
Added dodgy Where method to show how you might use it in query syntax. I don't suggest this is fantastic, but you might find it handy.
using System;
using System.Linq;
using System.Linq.Expressions;
static class Program
{
static void Main()
{
using (var ctx = new NorthwindDataContext())
{
ctx.Log = Console.Out;
// fluent API
var qry = ctx.Customers.Where(SomeFunc("a"));
Console.WriteLine(qry.Count());
// custom Where - purely for illustration
qry = from c in ctx.Customers
where SomeFunc("a")
select c;
Console.WriteLine(qry.Count());
}
}
static IQueryable<T> Where<T>(this IQueryable<T> query,
Func<T, Expression<Func<T, bool>>> predicate)
{
if(predicate==null) throw new ArgumentNullException("predicate");
return query.Where(predicate(default(T)));
}
static Expression<Func<Customer, bool>> SomeFunc(string arg)
{
return c => c.CompanyName.Contains(arg);
}
}
Basically, "out of the box", you can't have LINQ-to-SQL execute queries that have custom functions in them. In fact only some native methods that can be translated to SQL can be used.
The easiest way around this can unfortunately affect performance depending on how much data you're bringing back from the DB.
Basically, you can only use custom functions in WHERE statments if the data has already been loaded into memory, i.e, SQL have already executed.
The quickest fix for your example would look like this:
var query = from x in table.ToList() where SomeFunctionReturnsBool() select;
Notice the ToList(). It executes the SQL and puts the data into memory. You can now do whatever you want in the WHERE statement/method.
I would just break them out like so:
Expression<Func<Table, bool>> someTreeThatReturnsBool = x => true;
var query = from x in table where someTreeThatReturnsBool select x;
You could create functions that pass around expression trees.
Don't use query syntax for this.
var query = table.Where( x => SomeFunction(x) );