I'm using LLBLGen and I have some code like so:
if (onlyRecentMessages)
{
messageBucket.PredicateExpression.Add(MessageFields.DateEffective >= DateTime.Today.AddDays(-30));
}
var messageEntities = new EntityCollection<MessageEntity>();
using (var myAdapter = PersistenceLayer.GetDataAccessAdapter())
{
myAdapter.FetchEntityCollection(messageEntities, messageBucket);
}
I'm currently getting a SqlException on the FetchEntityCollection line. The error is:
System.Data.SqlClient.SqlException: The incoming tabular data stream (TDS) remote procedure call (RPC) protocol stream is incorrect. Too many parameters were provided in this RPC request. The maximum is 2100.
but that's a side note. What I actually want to be able to do is include the generated SQL in a custom exception in my code. So for instance something like this:
using (var myAdapter = PersistenceLayer.GetDataAccessAdapter())
{
try
{
myAdapter.FetchEntityCollection(messageEntities, messageBucket);
}
catch (SqlException ex)
{
throw new CustomSqlException(ex, myAdapter.GeneratedSqlFromLastOperation);
}
}
Of course, there is no such property as GeneratedSqlFromLastOperation. I'm aware that I can configure logging, but I would prefer to have the information directly in my stack track / exception so that my existing exception logging infrastructure can provide me with more information when these kinds of errors occur.
Thanks!
Steve
You should get an ORMQueryExecutionException, which contains the full query in the description. The query's execute method wraps all exceptions in an ORMQueryExecutionException and stores the query in the description.
ps: please, if possible ask llblgen pro related questions on our forums, as we don't monitor stackoverflow frequently. Thanks. :)
Related
I have a code similar to the one below. Every-time a DBLock appears, I want to get an alert in Dynatrace creating a problem so that I can see it on the dashboard and possibly get an email notification also. The DB lock would appear if the update count is greater than 1.
private int removeDBLock(DataSource dataSource) {
int updateCount = 0;
final Timestamp lastAllowedDBLockTime = new Timestamp(System.currentTimeMillis() - (5 * 60 * 1000));
final String query = format(RELEASE_DB_CHANGELOCK, lastAllowedDBLockTime.toString());
try (Statement stmt = dataSource.getConnection().createStatement()) {
updateCount = stmt.executeUpdate(query);
if(updateCount>0){
log.error("Stale DB Lock found. Locks Removed Count is {} .",updateCount);
}
} catch (SQLException e) {
log.error("Error while trying to find and remove Db Change Lock. ",e);
}
return updateCount;
}
I tried using the event API to trigger an event on my host mentioned here and was successful in raising a problem alert on my dashboard.
https://www.dynatrace.com/support/help/dynatrace-api/environment-api/events/post-event/?request-parameters%3C-%3Ejson-model=json-model
but this would mean injecting an api call in my code just for monitoring, any may lead to more external dependencies and hence more chance of failure.
I also tried creating a custom service detection by adding the class containing this method and the method itself in the custom service. But I do not know how I can link this to an alert or a event that creates a problem on the dashboard.
Are there any best practices or solutions on how I can do this in Dynatrace. Any leads would be helpful.
I would take a look at Custom Services for Java which will cause invocations of the method to be monitored in more detail.
Maybe you can extract a method which actually throws the exception and the outer method which handles it. Then it should be possible to alert on the exception.
There are also some more ways to configure the service via settings, i.e. raise an error based on a return value directly.
See also documentation:
https://www.dynatrace.com/support/help/how-to-use-dynatrace/transactions-and-services/configuration/define-custom-services/
https://www.dynatrace.com/support/help/technology-support/application-software/java/configuration-and-analysis/define-custom-java-services/
We're using PushStreamContent to stream some large lumps with Content-Disposition headers set and the like. As a number of people have discovered, the drawback is what happens when something goes wrong in the streaming?
At the very least, we were trying to get the error logged on our side so someone could follow up.
Recently, I ran into a weird situation. Putting a try/catch around the streaming function worked well enough for errors encountered before you actually started streaming (i.e. errors in sql queries and the like), but if the error occurred later (like in the serialization), the catch block doesn't fire.
Would anyone have any idea why that is?
e.g.
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
try
{
response.Content = new PushStreamContent((stream, content, context) =>
{
using (XmlWriter rWriter = PrepForXmlOutput(stream))
{
rpt.GenerateXmlReport(rWriter, reportParams, true);
}
}, "EventReport", extension);
}
catch (Exception e)
{
// The first step of GenerateXmlReport() is to run the sql;
// if the error happens there, this fires and will log the exception
// if the error happens later, during the result serialization, this does NOT fire
Log.Error(e);
}
return response;
Hate it when I see the answer just after I hit Post.
Try/catch around the outside only covers until I return the HttpResponseMessage. When/where I get the exception depends on how far the inner method gets before that return happens.
The try/catch needed to be on the inner call (the one where all the work happens) to cover the whole lifecycle.
I am trying to fetch Customer data to parse them into customer object to display on TableView. The following code sometimes works, sometimes not. Whenever it does crash, it shows Customer data is empty in the foreach loop even though I run the same code every time. I do not have clue what could be wrong in this circumstances. I am quite new on this platform. If I am missing anything/ extra information, please let me know.
namespace TableViewExample
{
public partial class MyDataServices : ContentPage
{
private ODataClient mODataClient;
private IEnumerable <IDictionary<string,object>> Customers;
public MyDataServices ()
{
InitializeComponent ();
InitializeDataService ();
GetDataFromOdataService ();
TableView tableView = new TableView{ };
var section = new TableSection ("Customer");
foreach (var customers in Customers) {
//System.Diagnostics.Debug.WriteLine ((string)customers ["ContactName"]);
var name = (string)customers ["ContactName"];
var cell = new TextCell{ Text = name };
section.Add (cell);
}
tableView.Root.Add (section);
Padding = new Thickness (10, 20, 10, 10);
Content = new StackLayout () {
Children = { tableView }
};
}
private void InitializeDataService(){
try {
mODataClient = new ODataClient ("myURL is here");
}
catch {
System.Diagnostics.Debug.WriteLine("ERROR!");
}
}
private void GetDataFromOdataService (){
try {
Customers = mODataClient.For ("Customers").FindEntries ();
}
catch {
System.Diagnostics.Debug.WriteLine("ERROR!");
}
}
}
}
Its hard helping out here, however here are some things to consider:-
It sounds like the dataservice could either be not contactable / offline; too busy or it could even be throwing an exception itself and returning a data response that you are not expecting to receive, that then triggers an exception and crash in your application as your always expecting an exact response without catering for any abnormal responses / events.
If you are contacting an external service over the internet it may just be your internet connection is slow / faulty and not returning the information fast enough as other possibilities.
In your code you are assuming that you always get a response from the server - and that this response will always be of an anticipated structure that your expecting to decode - without factoring in any possibility of abnormal responses returned by the dataservice. I have not used ODataClient personally, so not sure how it behaves in the event of maybe no data received / timeout or in your case the dataservice and how it behaves internally in the response to a bad-request etc.
I am assuming an exception would get thrown, and you do get your debug line executed indicating a failure.
You may want to also adjust this statement so that you write out the exception as well, i.e.:-
private void GetDataFromOdataService ()
{
try
{
Customers = mODataClient.For ("Customers").FindEntries ();
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("ERROR!" + ex.ToString());
}
}
If there was a bad response, then the line at Customers = ..... would throw the exception as there may be no Customers returned or some other information packaged in the response from the dataservice.
The Customers variable would also be null at this point I am assuming due to this failing.
So when you get back to your code at foreach (var customers in Customers) { it will then throw a null reference exception as Customers is infact null.
As all your current code executes in the constructor without any try and catch block around this, it will also crash your application at this point as well.
Also you are doing all of this work in the constructor. Try seperating this out. I haven't investigated exactly where the constructor gets called in an iOS page life-cycle, however, if it is in the viewDidLoad, then you have something like 10 seconds for everything to complete, otherwise it will exit automatically. I imagine in your case, this isn't applicable however.
Going forward also try putting your layout controls in the constructor, and move your data task to maybe the OnAppearing override instead.
Using async would definitely be advisable as well, but remember you need to inspect the response from your dataservice, as the error could be embedded within the response also and you will need to detect when it is OK to process the data.
I am writing a RESTful web service using spring 3 and I noticed that when I implemented my DAO's (I am using spring-jdbc for database access), the exceptions that get thrown are pretty generic, so i am not able to identify if the exception occurred because my database is down or my query failed.
sample code:
try {
Q q = jdbcTemplate.queryForObject(MY_QUERY, new Object[]{id}, new MyMapper());
return q;
} catch (DataAccessException e) {
// What is this exception ? database down ? query failed ?
}
Unless I know what exception is this during runtime, I can't send back reasonable error message to service client.
Any help is appreciated. Thanks
You shouldn't be trying to catch every single possible exception; code so that you don't run into the possibility of multiple user or programmer error type exceptions. Generally there are three type of exceptions that occur in every DAO regardless of what you do. (1) your database is down... imo if this is the issue you've got bigger problems. (2) user authentication error which is easy enough to catch and deal with (however you should probably be handling that situation on your RESTful front-end. (3) improper data. If you have bad data, just send the attempted data back and the reason for the exception.
try {
Q q = jdbcTemplate.queryForObject(MY_QUERY, new Object[]{id}, new MyMapper());
return q;
} catch (DataAccessException e) {
throw new DaoException("Could not retrieve q with ID: " + qID, e);
}
The method queryForObject only throws DataAccessException or IncorrectResultSizeDataAccessException. You shouldn't catch exception due to database connection failure at this level. However, in your DAO class, you normally have code to establish the dataSource which can be injected by Spring's IoC container. That part of code will throw exception if the database connection fails. You should catch DB failure exception there.
I am trying to perform a straighforward update using LinqToSQL, and just cannot get it to work.
Here's the data model: there is a timesheet_entry and customer. One customer has many timesheet_entries. It's a simple foreign key relationship.
If I'm editing an existing timesheet_entry, I get an exception if I change the customer_id.
Here's my attempt at the code. Can someone help me out here?
internal void CommitChangesToEntry(Timesheet_Entry entry)
{
Timesheet_Entry latest = (from e
in m_dataContext.Timesheet_Entries
where e.Timesheet_Entry_ID == entry.Timesheet_Entry_ID
select e).First();
latest.Entry_Start_DateTime = entry.Entry_Start_DateTime;
latest.Entry_End_DateTime = entry.Entry_End_DateTime;
latest.Task_Description = entry.Task_Description;
// Comment out this line of code and it
// doesn't throw an exception
latest.Customer_ID = entry.Customer_ID;
m_dataContext.SubmitChanges(); // This throws a NotSupportedException
}
The error is: "An attempt has been made to attach or add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported".
Do you have any reason for not using the Attach method? Like the following:
m_dataContext.Timesheet_Entries.Attach(entry);
m_dataContext.SubmitChanges();