I had the following:
$feedUrl = 'http://www.something.org/?feed=rss2';
$feed = Zend_Feed_Reader::import($feedUrl);
$lastNews = array();
//etc...
return $lastNews;
The problem was that, if the feed didn't exist for somereason, Zend will throw an exception and all my website will stay useless with that exception message.
I end up doing like this:
try {
$feedUrl = 'http://www.something.org/?feed=rss2';
$feed = Zend_Feed_Reader::import($feedUrl);
$lastNews = array();
//etc...
return $lastNews;
}
catch (Exception $e)
{
return false;
}
It works, but I just made up this. Not sure if it's ok. Any suggestions?
Regards,
MEM
That essentially the way you handle an Exception. Im not sure if i would return false, my preference would probably be for an empty array so that i dont have to have an if statement encapsulating loops that use the return value... but thats entirely up to you.
The only other exception would be to use a more specific exception like
try {
}
catch(Zend_Feed_Reader_Exception)
{
}
This way if a different error occurs you can handle it in a different fashion. Im not sure that exception actually exists but there is probably one or more exceptions unique tot he Zend_Feed component. Take a look at the code or docs to figure out which one(s) you want to catch and handle.
Related
Suppose "doc" is some document I want to insert into a MongoDB collection and "collection" is the collection I am inserting the document into.
I have something like the following:
try
{
WriteConcern wc = new WriteConcern();
wc.W = 1;
wc.Journal = true;
WriteConcernResult wcResult = collection.Insert(doc, wc);
if (!string.IsNullOrWhiteSpace(wcResult.ErrorMessage) || !wcResult.Ok)
{
return ErrorHandler(...);
}
else
{
return SuccessFunction(...);
}
}
catch (Exception e)
{
return e.Message;
}
Basically, if the insertion fails for any reason (other than hardware no longer working properly) I want to handle it (through the ErrorHandler function or the catch clause), while if it succeeds I want to call SuccessFunction.
My question: Is the above code sufficient for error checking purposes? In other words, will all failed insertions be caught, so that SuccessFunction is never called in those situations?
You don't even need to do any checking. collection.Insert will throw an exception if the write was not successful when you are using any write concern other than unacknowledged.
If you want to know if an error occured, you need to catch a WriteConcernException.
I started using Parse on Unity for a windows desktop game.
I save very simple objects in a very simple way.
Unfortunately, 10% of the time, i randomly get a 404 error on the SaveAsynch method :-(
This happen on different kind of ParseObject.
I also isolated the run context to avoid any external interference.
I checked the object id when this error happen and everything looks ok.
The strange thing is that 90% of the time, i save these objects without an error (during the same application run).
Did someone already got this problem ?
Just in case, here is my code (but there is nothing special i think):
{
encodedContent = Convert.ToBase64String(ZipHelper.CompressString(jsonDocument));
mLoadedParseObject[key]["encodedContent "] = encodedContent ;
mLoadedParseObject[key].SaveAsync().ContinueWith(OnTaskEnd);
}
....
void OnTaskEnd(Task task)
{
if (task.IsFaulted || task.IsCanceled)
OnTaskError(task); // print error ....
else
mState = States.SUCEEDED;
}
private void DoTest()
{
StartCoroutine(DoTestAsync());
}
private IEnumerator DoTestAsync()
{
yield return 1;
Terminal.Log("Starting 404 Test");
var obj = new ParseObject("Test1");
obj["encodedContent"] = "Hello World";
Terminal.Log("Saving");
obj.SaveAsync().ContinueWith(OnTaskEnd);
}
private void OnTaskEnd(Task task)
{
if (task.IsFaulted || task.IsCanceled)
Terminal.LogError(task.Exception.Message);
else
Terminal.LogSuccess("Thank You !");
}
Was not able to replicate. I got a Thank You. Could you try updating your Parse SDK.
EDIT
404 could be due to a bad username / password match. The exception messages are not the best.
The error above occurs when I try to do a dataReader.Read on the data recieved from the database. I know there are two rows in there so it isnt because no data actually exists.
Could it be the CommandBehavior.CloseConnection, causing the problem? I was told you had to do this right after a ExecuteReader? Is this correct?
try
{
_connection.Open();
using (_connection)
{
SqlCommand command = new SqlCommand("SELECT * FROM Structure", _connection);
SqlDataReader dataReader = command.ExecuteReader(CommandBehavior.CloseConnection);
if (dataReader == null) return null;
var newData = new List<Structure>();
while (dataReader.Read())
{
var entity = new Structure
{
Id = (int)dataReader["StructureID"],
Path = (string)dataReader["Path"],
PathLevel = (string)dataReader["PathLevel"],
Description = (string)dataReader["Description"]
};
newData.Add(entity);
}
dataReader.Close();
return newData;
}
}
catch (SqlException ex)
{
AddError(new ErrorModel("An SqlException error has occured whilst trying to return descendants", ErrorHelper.ErrorTypes.Critical, ex));
return null;
}
catch (Exception ex)
{
AddError(new ErrorModel("An error has occured whilst trying to return descendants", ErrorHelper.ErrorTypes.Critical, ex));
return null;
}
finally
{
_connection.Close();
}
}
Thanks in advance for any help.
Clare
When you use the Using in C#, after the last } from the using, the Connection automatically close, thats why you get the fieldcount to be closed when u try to read him, as that is impossible, because u want those datas, read then before close the using, or u can open and close manually the connection, by not using the (using)
Your code, as displayed is fine. I've taken it into a test project, and it works. It's not immediately clear why you get this message with the code shown above. Here are some debugging tips/suggestions. I hope they're valuable for you.
Create a breakpoint on the while (dataReader.Read()). Before it enters its codeblock, enter this in your Immediate or Watch Window: dataReader.HasRows. That should evaluate to true.
While stopped on that Read(), open your Locals window to inspect all the properties of dataReader. Ensure that the FieldCount is what you expect from your SELECT statement.
When stepping into this Read() iteration, does a student object get created at all? What's the value of dataReader["StructureID"] and all others in the Immediate Window?
It's not the CommandBehavior.CloseConnection causing the problem. That simply tells the connection to also close itself when you close the datareader.
When I got that error, it happened to be a command timeout problem (I was reading some large binary data). As a first attempt, I increased the command timeout (not the connection timeout!) and the problem was solved.
Note: while attempting to find out the problem, I tried to listen to the (Sql)connection's StateChanged event, but it turned out that the connection never fall in a "broken" state.
Same problem here. Tested all the above solutions
increase command timeout
close the connection after read
Here's the code
1 objCmd.Connection.Open()
2 objCmd.CommandTimeout = 3000
3 Dim objReader As OleDbDataReader = objCmd.ExecuteReader()
4 repeater.DataSource = objReader
5 CType(repeater, Control).DataBind()
6 objReader.Close()
7 objCmd.Connection.Dispose()
Moreover, at line 4 objReader has Closed = False
I got this exception while using the VS.NET debugger and trying to examine some IQueryable results. Bad decision because the IQueryable resulted in a large table scan. Stopping and restarting the debugger and NOT trying to preview this particular IQueryable was the workaround.
I have the following calls (actually a few more than this - it's the overall method that's in question here):
ThreadPool.QueueUserWorkItem(Database.Instance.RefreshEventData);
ThreadPool.QueueUserWorkItem(Database.Instance.RefreshLocationData);
ThreadPool.QueueUserWorkItem(Database.Instance.RefreshActData);
1st point is - is it OK to call methods that call WCF services like this? I tried daisy chaining them and it was a mess.
An example of one of the refresh methods being called above is (they all follow the same pattern, just call different services and populate different tables):
public void RefreshEventData (object state)
{
Console.WriteLine ("in RefreshEventData");
var eservices = new AppServicesClient (new BasicHttpBinding (), new EndpointAddress (this.ServciceUrl));
//default the delta to an old date so that if this is first run we get everything
var eventsLastUpdated = DateTime.Now.AddDays (-100);
try {
eventsLastUpdated = (from s in GuideStar.Data.Database.Main.Table<GuideStar.Data.Event> ()
orderby s.DateUpdated descending
select s).ToList ().FirstOrDefault ().DateUpdated;
} catch (Exception ex1) {
Console.WriteLine (ex1.Message);
}
try {
eservices.GetAuthorisedEventsWithExtendedDataAsync (this.User.Id, this.User.Password, eventsLastUpdated);
} catch (Exception ex) {
Console.WriteLine ("error updating events: " + ex.Message);
}
eservices.GetAuthorisedEventsWithExtendedDataCompleted += delegate(object sender, GetAuthorisedEventsWithExtendedDataCompletedEventArgs e) {
try {
List<Event> newEvents = e.Result.ToList ();
GuideStar.Data.Database.Main.EventsAdded = e.Result.Count ();
lock (GuideStar.Data.Database.Main) {
GuideStar.Data.Database.Main.Execute ("BEGIN");
foreach (var s in newEvents) {
GuideStar.Data.Database.Main.InsertOrUpdateEvent (new GuideStar.Data.Event {
Name = s.Name,
DateAdded = s.DateAdded,
DateUpdated = s.DateUpdated,
Deleted = s.Deleted,
StartDate = s.StartDate,
Id = s.Id,
Lat = s.Lat,
Long = s.Long
});
}
GuideStar.Data.Database.Main.Execute ("COMMIT");
LocationsCount = 0;
}
} catch (Exception ex) {
Console.WriteLine("error InsertOrUpdateEvent " + ex.Message);
} finally {
OnDatabaseUpdateStepCompleted (EventArgs.Empty);
}
};
}
OnDatabaseUpdateStepCompleted - just iterates an updateComplete counter when it's called and when it knows that all of the services have come back ok it removes the waiting spinner and the app carries on.
This works OK 1st time 'round - but then sometimes it doesn't with one of these: http://monobin.com/__m6c83107d
I think the 1st question is - is all this OK? I'm not used to using threading and locks so I am wandering into new ground for me. Is using QueueUserWorkItem like this ok? Should I even be using lock before doing the bulk insert/update? An example of which:
public void InsertOrUpdateEvent(Event festival){
try {
if (!festival.Deleted) {
Main.Insert(festival, "OR REPLACE");
}else{
Main.Delete<Event>(festival);
}
} catch (Exception ex) {
Console.WriteLine("InsertOrUpdateEvent failed: " + ex.Message);
}
}
Then the next question is - what am I doing wrong that is causing these sqlite issues?
w://
Sqlite is not thread safe.
If you want to access Sqlite from more than one thread, you must take a lock before you access any SQLite related structures.
Like this:
lock (db){
// Do your query or insert here
}
Sorry, no specific answers, but some thoughts:
Is SqlLite even threadsafe? I'm not sure - it may be that it's not (to the wrapper isn't). Can you lock on a more global object, so no two threads are inserting at the same time?
It's possible that the MT GC is getting a little overenthusiastic, and releasing your string before it's been used. Maybe keep a local reference to it around during the insert? I've had this happen with view controllers, where I had them in an array (tabcontrollers, specificially), but if I didn't keep an member variable around with the reference, they got GC'ed.
Could you get the data in a threaded manner, then queue everything up and insert them in a single thread? Atleast as a test anyway.
I have this code in C++/CLI project:
CSafePtr<IEngine> engine;
HMODULE libraryHandle;
libraryHandle = LoadLibraryEx("FREngine.dll", 0, LOAD_WITH_ALTERED_SEARCH_PATH);
typedef HRESULT (STDAPICALLTYPE* GetEngineObjectFunc)(BSTR, BSTR, BSTR, IEngine**);
GetEngineObjectFunc pGetEngineObject = (GetEngineObjectFunc)GetProcAddress(libraryHandle, "GetEngineObject");
pGetEngineObject( freDeveloperSN, 0, 0, &engine )
last line throws this exception:
RPC Server in not available
What may causing this exception?
ABBYY FRE is a COM object. GetEngineObject() behaves like a normal COM interface method except it's a separate function. Which means the following: it doesn't allow exceptions propagate outside. To achieve this it catches all exceptions, translates them into appropriate HRESULT values and possibly sets up IErrorInfo.
You trying to analyze the exception thrown inside a method have no chances to find what the problem is. That's because internally it might work like this:
HRESULT GetEngineObject( params )
{
try {
//that's for illustartion, code could be more comlex
initializeProtection( params );
obtainEngineObject( params );
} catch( std::exception& e ) {
setErrorInfo( e ); //this will set up IErrorInfo
return translateException( e ); // this will produce a relevant HRESULT
}
return S_OK;
}
void intializeProtection()
{
try {
doInitializeProtection();//maybe deep inside that exception is thrown
///blahblahblah
} catch( std::exception& e ) {
//here it will be translated to a more meaningful one
throw someOtherException( "Can't initialize protection: " + e.what() );
}
}
so the actual call can catch exceptions and translate them to provide meaningful diagnostics. In order to obtain tha diagnostics you need to retrieve IErrorInfo* after the function retuns. Use code from check() function from the same example project for that. Just don't stare at the exception being thrown - you have no chances with that, let it propagate and be translated.