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  • GAE, JDO, count() doesn't work ?

    - by NilsBor
    On GAE with Spring/JDO after saving 2 entities (in transaction). On calling getById - entities fetched from data storage. On calling getCount() returns "0" and - on calling getAll() - returns empty collection. plz help me ! DAO: @Override public Long getCount() { return ((Integer) getJdoTemplate().execute(new JdoCallback() { @Override public Object doInJdo(PersistenceManager pm) throws JDOException { Query q = pm.newQuery(getPersistentClass()); q.setResult("count(this)"); return q.execute(); } })).longValue(); } @Override public void saveOrUpdate(T entity) { getJdoTemplate().makePersistent(entity); } @Override public List getAll() { return new ArrayList(getJdoTemplate().find(getPersistentClass())); }

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  • How to check a SQL database table to see if a record exists

    - by Anthony
    I have a SQL database that creates a record for every document uploaded by the user to the server. I want to check this table before a user uploads a document to ensure they don't upload a file with name that already exists. I know how to make the connection and make the SqlCommand to query the table for an existing record. But I don't know how to check the record count from the sqlCommand I made. Does that make sense? Using myConnectionCheck As New SqlConnection(myConnectionStringCheck) Dim myCommandCheck As New SqlCommand() myCommandCheck.Connection = myConnectionCheck myCommandCheck.CommandText = "SELECT * FROM Req_Docs WHERE Doc_Name =" & DocName myConnectionCheck.Open() myCommandCheck.ExecuteNonQuery() End Using Thanks in advance, Anthony

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  • (Google AppEngine) Memcache Lock Entry

    - by Friedrich
    Hi, i need a locking in memcache. Since all operations are atomic that should be an easy task. My idea is to use a basic spin-lock mechanism. So every object that needs locking in memcache gets a lock object, which will be polled for access. // pseudo code // try to get a lock int lock; do { lock = Memcache.increment("lock", 1); } while(lock != 1) // ok we got the lock // do something here // and finally unlock Memcache.put("lock", 0); How does such a solution perform? Do you have a better idea how to lock a memcache object? Best regards, Friedrich Schick

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  • Debug PyDev+Eclipse - Code not reloads after code change in breakpoint/suspend mode

    - by Chameleon
    I often doing such steps and want to optimize debug speed: I am setting some breakpoints. I am running Google Appengine Application (Python 2.5.2+). When breakpoint occur I often change code to fix bugs. After code change want to test again but there is problem if I changed code in breakpoint/suspend mode the application does not updates with my code changes - thus requiring a slow reloading. Does anybody have an idea of what is root cause of forcing reloading after suspend or it is PyDev Bug/Limitation?

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  • Empty list in appengine datastore: java vs python

    - by lOranger
    I have the following java model class in AppEngine: public class Xyz ... { @Persistent private Set<Long> uvw; } When saving an object Xyz with an empty set uvw in Java, I get a "null" field (as listed in the appengine datastore viewer). When I try to load the same object in python (through remote_api), as defined by the following python model class: class Xys(db.Model): uvw = db.ListProperty(int) I get a "BadValueError: Property uvw is required". When saving another object of the same class in python with an empty uvw list, the datastore viewer print a "missing" field. Apparently empty lists storage handling differs between Java and python and lead to "incompatible" objects. Thus my question: Is there a way to, either: force Java to store an empty list as a "missing" field, force Python to gracefully accept a "null" list as an empty list when loading the object? Or any other suggestion on how to handle empty list field in both languages. Thanks for your answers!

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  • Lucene.NET performance

    - by Paul Knopf
    I have a website that runs of a third party search provider that is expensive. I am going to roll my own. Is Lucene.NET capable of ~25,000 products (or documents), each with maybe ten attributes used for filtering? I am looking to do a "narrow/drill down" or "faceted search". Does that sound like to much to ask from Lucene.NET?

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  • Generating a reasonable ctags database for Boost

    - by Robert S. Barnes
    I'm running Ubuntu 8.04 and I ran the command: $ ctags -R --c++-kinds=+p --fields=+iaS --extra=+q -f ~/.vim/tags/stdlibcpp /usr/include/c++/4.2.4/ to generate a ctags database for the standard C++ library and STL ( libstdc++ ) on my system for use with the OmniCppComplete vim script. This gave me a very reasonable 4MB tags file which seems to work fairly well. However, when I ran the same command against the installed Boost headers: $ ctags -R --c++-kinds=+p --fields=+iaS --extra=+q -f ~/.vim/tags/boost /usr/include/boost/ I ended up with a 1.4 GB tags file! I haven't tried it yet, but that seems likes it's going to be too large to be useful. Is there a way to get a slimmer, more usable tags file for my installed Boost headers? Edit Just as a note, libstdc++ includes TR1, which has allot of Boost libs in it. So there must be something weird going on for libstdc++ to come out with a 4 MB tags file and Boost to end up with a 1.4 GB tags file.

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  • Feeding a Drill Down Menu with categories, subcategories and subSubcategories from a database

    - by Hassan
    Hi everyone, I have a Drill Down menu and I want to have it gets its elements from a database, I am using php and MySQL and the table (categories) looks like this : http://yfrog.com/jctablehsj I can't figure out how I can extract these information in a way I could put it inside the Drill Down Menu ! I found the recursive method (with LEFT JOINs) and the nested method which I barely understood and again I couldn't apply it to the Drill Down Menu. I found that some people found out a solution with left join and group by but couldn't understand or copy their example ! I would be more than gratefull if you could give me the extact of the query. Thanks a lot for your hard work, Hassan

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  • Datastore performance, my code or the datastore latency

    - by fredrik
    I had for the last month a bit of a problem with a quite basic datastore query. It involves 2 db.Models with one referring to the other with a db.ReferenceProperty. The problem is that according to the admin logs the request takes about 2-4 seconds to complete. I strip it down to a bare form and a list to display the results. The put works fine, but the get accumulates (in my opinion) way to much cpu time. #The get look like this: outputData['items'] = {} labelsData = Label.all() for label in labelsData: labelItem = label.item.name if labelItem not in outputData['items']: outputData['items'][labelItem] = { 'item' : labelItem, 'labels' : [] } outputData['items'][labelItem]['labels'].append(label.text) path = os.path.join(os.path.dirname(__file__), 'index.html') self.response.out.write(template.render(path, outputData)) #And the models: class Item(db.Model): name = db.StringProperty() class Label(db.Model): text = db.StringProperty() lang = db.StringProperty() item = db.ReferenceProperty(Item) I've tried to make it a number of different way ie. instead of ReferenceProperty storing all Label keys in the Item Model as a db.ListProperty. My test data is just 10 rows in Item and 40 in Label. So my questions: Is it a fools errand to try to optimize this since the high cpu usage is due to the problems with the datastore or have I just screwed up somewhere in the code? ..fredrik

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  • Drupal, mysql server settings

    - by Patrick
    hi, I've a problem to configure database settings in Drupal. I will propose here some sample data: Database Mysql: Database: databaseName User: user Password: password Server: server.com Server Choice: mysqldb2 (in phpmyadmin I have this option and I can choose between mysqldb1 and mysqldb2 to access to the mysql server) The error message I get is: The mysql error was: Access denied for user: 'user@localhost' (Using password: YES). I've tried the following lines in settings.php but I always get the same error message: $db_url = 'mysql://user:password@localhost/databaseName'; $db_url = 'mysql://user:password@localhost/databaseName/mysqldb2'; The user and password work in phpmyadmin so I'm sure they are correct. thanks

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  • Spring security with GAE

    - by xybrek
    I'm trying to implement Spring security for my GAE application however I'm getting this error: No bean named 'springSecurityFilterChain' is defined I added this configuration on my application web.xml: <filter> <filter-name>springSecurityFilterChain</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping> <filter-name>springSecurityFilterChain</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> And in the servlet-context: <!-- Configure security --> <security:http auto-config="true"> <security:intercept-url pattern="/**" access="ROLE_USER" /> </security:http> <security:authentication-manager alias="authenticationManager"> <security:authentication-provider> <security:user-service> <security:user name="jimi" password="jimi" authorities="ROLE_USER, ROLE_ADMIN" /> <security:user name="bob" password="bob" authorities="ROLE_USER" /> </security:user-service> </security:authentication-provider> </security:authentication-manager> What could be causing the error?

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  • High-concurrency counters without sharding

    - by dound
    This question concerns two implementations of counters which are intended to scale without sharding (with a tradeoff that they might under-count in some situations): http://appengine-cookbook.appspot.com/recipe/high-concurrency-counters-without-sharding/ (the code in the comments) http://blog.notdot.net/2010/04/High-concurrency-counters-without-sharding My questions: With respect to #1: Running memcache.decr() in a deferred, transactional task seems like overkill. If memcache.decr() is done outside the transaction, I think the worst-case is the transaction fails and we miss counting whatever we decremented. Am I overlooking some other problem that could occur by doing this? What are the significiant tradeoffs between the two implementations? Here are the tradeoffs I see: #2 does not require datastore transactions. To get the counter's value, #2 requires a datastore fetch while with #1 typically only needs to do a memcache.get() and memcache.add(). When incrementing a counter, both call memcache.incr(). Periodically, #2 adds a task to the task queue while #1 transactionally performs a datastore get and put. #1 also always performs memcache.add() (to test whether it is time to persist the counter to the datastore). Conclusions (without actually running any performance tests): #1 should typically be faster at retrieving a counter (#1 memcache vs #2 datastore). Though #1 has to perform an extra memcache.add() too. However, #2 should be faster when updating counters (#1 datastore get+put vs #2 enqueue a task). On the other hand, with #1 you have to be a bit more careful with the update interval since the task queue quota is almost 100x smaller than either the datastore or memcahce APIs.

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  • GAE datastore eager loading in python api

    - by tomus
    I have two models in relation one-to-many: class Question(db.Model): questionText = db.StringProperty(multiline=False) class Answer(db.Model): answerText = db.StringProperty(multiline=False) question = db.ReferenceProperty(Question, collection_name='answers') I have front-end implemented in Flex and use pyamf to load data. When i try to load all answers with related questions all works as desired and I can access field answer.question however in case of loading questions (e.g. by Questions.all() ), 'question.answers' remains empty/null (though on server/python side I can revise question.answers without problem - probably after lazy-loading). So is it possible to load all questions along with answers ? (I know this is possible in JPA Java api but what about python ?) Shoud I use additional setting, GQL query or django framework to make it work ?

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  • SQL Server 2005 script with join across Database Servers

    - by Robin Day
    I have the following script which I use to give me a simple "diff" between tables on two different databases. (Note: In reality my comparison is on a lot more than just an ID) SELECT MyTableA.MyId, MyTableB.MyId FROM MyDataBaseA..MyTable MyTableA FULL OUTER JOIN MyDataBaseB..MyTable MyTableB ON MyTableA.MyId = MyTableB.MyId WHERE MyTableA.MyId IS NULL OR MyTableB.MyId IS NULL I now need to run this script on two databases that exist on different servers. At the moment my solution is to backup the database from one server, restore it to the other and then run the script. I'm pretty sure this is possible, however, is this likely to be a can of worms? This is a very rare task I need to perform and if it involves a large number of DB setting changes then I will probably stick to my backup method.

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  • unable to add objects to saved collection in GAE using JDO

    - by Jeffrey Chee
    I have a ClassA containing an ArrayList of another ClassB I can save a new instance of ClassA with ClassB instances also saved using JDO. However, When I retrieve the instance of Class A, I try to do like the below: ClassA instance = PMF.get().getPersistenceManager().GetObjectByID( someid ); instance.GetClassBArrayList().add( new ClassB(...) ); I get an Exception like the below: Uncaught exception from servlet com.google.appengine.api.datastore.DatastoreNeedIndexException: no matching index found.. So I was wondering, Is it possible to add a new item to the previously saved collection? Or was it something I missed out. Best Regards

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  • Computer Vision application(+web interface) for face detection and recognition from database

    - by Kush
    My project is a computer vision java application which should implement the following : A web interface through which the form entry+images(for example a student data) will be stored into a database(Mysql) & images into directory common to my java application. Then the data & images can be retrieved from my java Gui application and I can perform the following operations of image processing through OpenCV. Actually,I want to run the face detection on images retrieved and discard the false entries(no proper face). Also the application user/admin can search an image based on text search(By Id) or By another reference image using face recognition. I am well familiar with Java but the problem is that I need a guidance on how to organise it in a stepwise manner(links appreciated).OpenCv,Php and mySql are really messy.I know doing the openCV stuff within java is real overhead but i really want to do it.But If there is any suggestion to do it elseway please guide me.So any kind of help is a ray of hope for me. Thanks.

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  • asp.net search application index update help

    - by srinivasan
    hi im developing a simple search application( ASP.Net VB.Net) the index table is actually a hash table ll be stored in my file system. the search page ll open this in read mode n copy this to a hash table object n perform search. other update n delete functions will open this in write mode n update it. what should i ve to do to make this app correct that there shud not be any execption when multiple user accessing these things at the same time. wat do i ve to do to make this robust and error free. i want multiple users to access search page without any problem n the index updation also in a parallel manner thanks srinivasan

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  • Convert BLOB to Jpg using C#

    - by TGuimond
    Hello, I am currently developing a web application that receives data from an on-site oracle database. The database developers have developed some web-services that I am able to call and send/receive data to and from the the database. When I want to display an image the method returns the image in BLOB format. My question is: what is the best way to convert BLOB to .jpg or .bmp so I can display the image correctly? If someone could point me in the right direction that would be great! Cheers, Tristan

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  • base for setQueueXmlPath

    - by antony.trupe
    I can't figure out how to point unit tests at the queue config file. Unit Test snippet // TaskQueue setup LocalTaskQueueTestConfig tqConfig = new LocalTaskQueueTestConfig(); tqConfig.setQueueXmlPath("/war/WEB_INF/queue.xml"); Stack Trace java.lang.IllegalStateException: The specified queue is unknown : zip-fetch at com.google.appengine.api.labs.taskqueue.QueueApiHelper.translateError(QueueApiHelper.java:56) at com.google.appengine.api.labs.taskqueue.QueueApiHelper.translateError(QueueApiHelper.java:111) at com.google.appengine.api.labs.taskqueue.QueueApiHelper.makeSyncCall(QueueApiHelper.java:32) at com.google.appengine.api.labs.taskqueue.QueueImpl.add(QueueImpl.java:310) at com.google.appengine.api.labs.taskqueue.QueueImpl.add(QueueImpl.java:282) at com.google.appengine.api.labs.taskqueue.QueueImpl.add(QueueImpl.java:267) at ...

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  • Best Design for a Facebook clone on GAE Java

    - by charming30
    My current App is written in Python on GAE which can do Contacts management, Genealogy, Social Networking, Photo sharing, Telecom Integration (SMS, iVRS, URL Billing), CRON and performs business logic operations for our Mobile Apps. Current Architecture indlues python, django, jquery, memcache and few telecom APIs. Now, It feels that an SOA Architecture on GAE using Java would be really ideal and scalable for this kind of App where we want to build new features like widgets that users can turn on or off and third party developers can also develop and deploy features. Please correct me or improve the following design decision: UI (Current plan is GWT) Sessions, Security and ACL (Spring MVC 2.x) Reusable Business Logic components (?) Implementation of Web Services (?) Your advice would really help.

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  • Detecting first time login of user into application (Google Appengine)

    - by Jake
    My app requires users to login using their google account. I have this set in my App.yamp file: url: /user/.* script: user.py login: required Now when any user tries to access files under /user/secret.py he will need to authenticate via google, which will redirect the user back to /user/secret.py after successful authentication. Now the problem I am facing is when the user is redirected back to the app, I cannot be sure if this is the first time the user has logged in or is it a regular user to my site who has come back again from just the user object which google passes using users.get_current_user() . I thus need to maintain state in the datastore to check if the user already exists or not everytime. If he does not exist i need to create a new entry with other application specific settings. My question is: Is there some easier way to handle this? without having to query the datastore to figure if this is a first time user or a regular one?

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  • blobstore upload code not working

    - by Bunny Rabbit
    <body> <form action="<%= blobstoreService.createUploadUrl("/upload") %>" method="post" enctype="multipart/form-data"> <input type="file" name="myFile"> <input type="submit" value="Submit"> </form> </body> the above code throws a java.lang.NoSuchMethodError on compilation.I can't understand and what is blobstoreService in the above code ?

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  • Recommendation for web-based database visualization tool

    - by prometheus
    Tableau is extremely flexible when it comes to visualizing and playing around with datasets, but it is extremely slow when you go into "production mode" and publish a particular view that you've created onto your server. Does anyone know of any tools that can be used to connect to a database, present interactive (or somewhat interactive) dashboards, and perform reasonably well when published to a server? To be clearer, I am looking for something like this -- http://www.corda.com/executive-dashboard-graph-styles.php. I realize that such a product might not exist. If so, is there a particular framework or library that I could use to create killer interactive visualizations of data for the web?

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