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  • Google App Engine, parsedatetime and TimeZones

    - by Ron
    Hey guys, I'm working on a Google App Engine / Django app and I encountered the following problem: In my html I have an input for time. The input is free text - the user types "in 1 hour" or "tomorrow at 11am". The text is then sent to the server in AJAX, which parses it using this python library: http://code.google.com/p/parsedatetime/. Once parsed, the server returns an epoch timestamp of the time. Here is the problem - Google App Engine always runs on UTC. Therefore, lets say that the local time is now 11am and the UTC time is 2am. When I send "now" to the server it will return "2am", which is good because I want the date to be received in UTC time. When I send "in 1 hour" the server will return "3am" which is good, again. However, when I send "at noon" the server will return "12pm" because it thinks that I'm talking about noon UTC - but really I need it to return 3am, which is noon for the request sender.. I can pass on the TZ of the browser that sends the request, but that wont really help me - the parsedatetime library wont take a timezone argument (correct me if I'm wrong). Is there a walk around this? Maybe setting the environments TZ somehow? Thanks!

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  • Javascript JQUERY AJAX: When Are These Implemented

    - by Michael Moreno
    I'm learning javascript. Poked around this excellent site to gather intel. Keep coming across questions / answers about javascript, JQUERY, JQUERY with AJAX, javascript with JQUERY, AJAX alone. My conclusion: these are all individually powerful and useful. My confusion: how does one determine which/which combination to use ? I've concluded that javascript is readily available on most browsers. For example, I can extend a simple HTML page with <html> <body> <script type="text/javascript"> document.write("Hello World!"); </script> </body> </html> However, within the scope of Python/DJANGO, many of these questions are JQUERY and AJAX related. At which point or under what development circumstances would I conclude that javascript alone isn't going to "cut it", and I need to implement JQUERY and/or AJAX and/or some other permutation ?

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  • accessing list sent from server as JSON object

    - by tazim
    How to access a list sent in form of json object using django to the template received in ajax callback function . The code is as follows : views.py def showfiledata(request): with open("/home/tazim/webexample/test.txt") as f: list = f.readlines() f.closed return_dict = {'filedata':list} json = simplejson.dumps(return_dict) HttpResponse(json,mimetype="application/json") in template showfile.html: < html> < head> < script type="text/javascript" src="/jquerycall/">< /script> < script type="text/javascript"> $(document).ready(function() { $("button").click(function() { $.ajax({ type:"POST", url:"/showfiledata/", datatype:"json", success:function(data) { var s = data.filedata; $("#someid").html(s); } }); }); }); < /script> < /head> < body> < form method="post"> < button type="button">Click Me< /button> < div id="someid">< /div> < /form> < /body> < /html>

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  • JQuery tablesorter - Second click on column header doesn't resort

    - by Jonathan
    I'm using tablesorter in on a table I added to a view in django's admin (although I'm not sure this is relevant). I'm extending the html's header: {% block extrahead %} <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.js"></script> <script type="text/javascript" src="http://mysite.com/media/tablesorter/jquery.tablesorter.js"></script> <script type="text/javascript"> $(document).ready(function() { $("#myTable").tablesorter(); } ); </script> {% endblock %} When I click on a column header, it sorts the table using this column in descending order - that's ok. When I click the same column header a second time - it does not reorder to ascending order. What's wrong with it? the table's html looks like: <table id="myTable" border="1"> <thead> <tr> <th>column_name_1</th> <th>column_name_2</th> <th>column_name_3</th> </tr> </thead> <tbody> {% for item in extra.items %} <tr> <td>{{ item.0|safe }} </td> <td>{{ item.1|safe }} </td> <td>{{ item.2|safe }} </td> </tr> {% endfor %} </tbody> </table>

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  • Multiple Inheritence with same Base Classes in Python

    - by Jordan Reiter
    I'm trying to wrap my head around multiple inheritance in python. Suppose I have the following base class: class Structure(object): def build(self, *args): print "I am building a structure!" self.components = args And let's say I have two classes that inherit from it: class House(Structure): def build(self, *args): print "I am building a house!" super(House, self).build(*args) class School(Structure): def build(self, type="Elementary", *args): print "I am building a school!" super(School, self).build(*args) Finally, a create a class that uses multiple inheritance: class SchoolHouse(School, House): def build(self, *args): print "I am building a schoolhouse!" super(School, self).build(*args) Then, I create a SchoolHouse object and run build on it: >>> sh = SchoolHouse() >>> sh.build("roof", "walls") I am building a schoolhouse! I am building a house! I am building a structure! So I'm wondering -- what happened to the School class? Is there any way to get Python to run both somehow? I'm wondering specifically because there are a fair number of Django packages out there that provide custom Managers for models. But there doesn't appear to be a way to combine them without writing one or the other of the Managers as inheriting from the other one. It'd be nice to just import both and use both somehow, but looks like it can't be done? Also I guess it'd just help to be pointed to a good primer on multiple inheritance in Python. I have done some work with Mixins before and really enjoy using them. I guess I just wonder if there is any elegant way to combine functionality from two different classes when they inherit from the same base class.

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  • Multiple use of a form before it is submitted

    - by OregonTrail
    I'm new to JavaScript, and trying to figure out the canonical way to do the following. I have a form with some checkboxes and a selector. Let's say the checkboxes are styles of music and the selector is for people's names. I'd like the user to be able to select the styles of music for each of the people's names and then submit the form with all of the data. For example, the user might first check off Classical, Jazz, Rock, and Pop and choose "Joe", then select Jazz, Pop, Country, and Electronica and choose "Jane". So there would have to be two different buttons for "submit person" and "submit form". I would like to: Have a list of the names and their chosen styles populate below the form, for feedback Allow the user to use the form as much as they want, and then submit all the data at the end I get the feeling that using jquery and JSON is perfect for this, but I'm not sure what search terminology to use to figure out how to do this. If it matters, the form will be processed by a Django view in Python.

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  • Declare models elsewhere than in "models.py"

    - by sebpiq
    Hi ! I have an application that splits models into different files. Actually the folder looks like : >myapp __init__.py models.py >hooks ... ... myapp don't care about what's in the hooks, folder, except that there are models, and that they have to be declared somehow. So, I put this in myapp.__init__.py : from django.conf import settings for hook in settings.HOOKS : try : __import__(hook) except ImportError as e : print "Got import err !", e #where HOOKS = ("myapp.hooks.a_super_hook1", ...) The problem is that it doesn't work when I run syncdb(and throws some strange "Got import err !"... strange considering that it's related to another module of my program that I don't even import anywhere :/ ) ! So I tried successively : 1) for hook in settings.HOOKS : try : exec ("from %s import *" % hook) doesn't work either : syncdb doesn't install the models in hooks 2) from myapp.hooks.a_super_hook1 import * This works 3) exec("from myapp.hooks.a_super_hook1 import *") This works to So I checked that in the test 1), the statement executed is the same than in tests 2) and 3), and it is exactly the same ... Any idea ???

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  • Help a CRUD programmer think about an "approval workflow"

    - by gerdemb
    I've been working on a web application that is basically a CRUD application (Create, Read, Update, Delete). Recently, I've started working on what I'm calling an "approval workflow". Basically, a request is generated for a material and then sent for approval to a manager. Depending on what is requested, different people need to approve the request or perhaps send it back to the requester for modification. The approvers need to keep track of what to approve what has been approved and the requesters need to see the status of their requests. As a "CRUD" developer, I'm having a hard-time wrapping my head around how to design this. What database tables should I have? How do I keep track of the state of the request? How should I notify users of actions that have happened to their requests? Is their a design pattern that could help me with this? Should I be drawing state-machines in my code? I think this is a generic programing question, but if it makes any difference I'm using Django with MySQL.

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  • Saving animated GIFs using urllib.urlopen (image saved does not animate)

    - by wenbert
    I have Apache2 + Django + X-sendfile. My problem is that when I upload an animated GIF, it won't "animate" when I output through the browser. Here is my code to display the image located outside the public accessible directory. def raw(request,uuid): target = str(uuid).split('.')[:-1][0] image = Uploads.objects.get(uuid=target) path = image.path filepath = os.path.join(path,"%s.%s" % (image.uuid,image.ext)) response = HttpResponse(mimetype=mimetypes.guess_type(filepath)) response['Content-Disposition']='filename="%s"'\ %smart_str(image.filename) response["X-Sendfile"] = filepath response['Content-length'] = os.stat(filepath).st_size return response UPDATE It turns out that it works. My problem is when I try to upload an image via URL. It probably doesn't save the entire GIF? def handle_url_file(request): """ Open a file from a URL. Split the file to get the filename and extension. Generate a random uuid using rand1() Then save the file. Return the UUID when successful. """ try: file = urllib.urlopen(request.POST['url']) randname = rand1(settings.RANDOM_ID_LENGTH) newfilename = request.POST['url'].split('/')[-1] ext = str(newfilename.split('.')[-1]).lower() im = cStringIO.StringIO(file.read()) # constructs a StringIO holding the image img = Image.open(im) filehash = checkhash(im) image = Uploads.objects.get(filehash=filehash) uuid = image.uuid return "%s" % (uuid) except Uploads.DoesNotExist: img.save(os.path.join(settings.UPLOAD_DIRECTORY,(("%s.%s")%(randname,ext)))) del img filesize = os.stat(os.path.join(settings.UPLOAD_DIRECTORY,(("%s.%s")%(randname,ext)))).st_size upload = Uploads( ip = request.META['REMOTE_ADDR'], filename = newfilename, uuid = randname, ext = ext, path = settings.UPLOAD_DIRECTORY, views = 1, bandwidth = filesize, source = request.POST['url'], size = filesize, filehash = filehash, ) upload.save() #return uuid return "%s" % (upload.uuid) except IOError, e: raise e Any ideas? Thanks! Wenbert

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  • How do I handle the messages for a simple web-based live chat, on the server side?

    - by Carson Myers
    I'm building a simple live chat into a web application running on Django, but one thing I'm confused about is how I should store the messages between users. The chat will support multiple users, and a chat "session" is composed of users connected to one user that is the "host." The application is a sort of online document collaboration thing, so user X has a document, and users Y and Z would connect to user X to talk about the document, and that would be one chat session. If user Y disconnected for five minutes, and then signed back in and reconnected to user X, he should not get any of the messages shared between users X and Z while he was away. if users X, Y, and Z can have a chat session about user X's document, then users X and Y can connect to a simultaneous, but separate discussion about user Z's document. How should I handle this? Should I keep each message in the database? Each message would have an owner user and a target user (the host), and a separate table would be used to connect users with messages (which messages are visible to what users). Or should I store each session as an HTML file on the server, which messages get appended to? The problem is, I can't just send messages directly between clients. They have to be sent to the server in a POST request, and then each client has to periodically check for the messages in a GET request. Except I can't just have each message cleared after a client fetches it, because there could be multiple clients. How should I set this up? Any suggestions?

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  • Design an Application That Stores and Processes Files

    - by phasetwenty
    I'm tasked with writing an application that acts as a central storage point for files (usually document formats) as provided by other applications. It also needs to take commands like "file 395 needs a copy in X format", at which point some work is offloaded to a 3rd party application. I'm having trouble coming up with a strategy for this. I'd like to keep the design as simple as possible, so I'd like to avoid big extra frameworks or techniques like threads for as long as it makes sense. The clients are expected to be web applications (for example, one is a django application that receives files from our customers; the others are not yet implemented). The platform it will be running on is likely going to be Python on Linux, unless I have a strong argument to use something else. In the beginning I thought I could fit the information I wanted to communicate in the filenames, and let my application parse the filename to figure out what it needed to do, but this is proving too inflexible with the amount of information I'm realizing I need to make available. Another idea is to pair FTP with a database used as a communication medium (client uploads a file and updates the database with a command as a row in a table) but I don't like this idea because adding commands (a known change) looks like it will require adding code as well as changing database schemas. It will also muddy up the interface my clients will have to use. I looked into Pyro to let applications communicate more directly but I don't like the idea of running an extra nameserver for this one purpose. I also don't see a good way to do file transfer within this framework. What I'm looking for is techniques and/or technologies applicable to my problem. At the simplest level, I need the ability to accept files and messages with them.

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  • How can several different datatypes be saved in one table

    - by poseidon
    This is my situation: I am constructing an ad-like application in Django and Mysql. I am using a flexible-ad approach where we have: a table with ad categories (several categories such as home, furniture, cars, etc.) id_category name a table with details for the ad categories (home: area, squared meters. car: seats, color.) id_detail id_category (the categ the detail describes) name type (boolean, char, int, long, etc.) the ad table (i am selling a house. i am selling a car.) id_ad id_category text date a table where i plan to consolidate the details of the ads (home: A-area, 500 sq-meters. car: 5 seats, red.) id_detail_ad id_ad id_detail value Is this possible? Can I have a table of details for all the ads, even if details include numbers, texts, booleans, etc? Or would I have to save them all as text and then interpret them via code accordingly? Please express your opinions. Thank you.

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  • Processing forms that generate many rows in DB

    - by Zack
    I'm wondering what the best approach to take here is. I've got a form that people use to register for a class and a lot of times the manager of a company will register multiple people for the class at the same time. Presently, they'd have to go through the registration process multiple times and resubmit the form once for every person they want to register. What I want to do is give the user a form that has a single <input/> for one person to register with, along with all the other fields they'll need to fill out (Email, phone number, etc); if they want to add more people, they'll be able to press a button and a new <input/> will be generated. This part I know how to do, but I'm including it to best describe what I'm aiming to do. The part I don't know how to approach is processing that data the form submits, I need some way of making a new row in the Registrant table for every <input/> that's added and include the same contact information (phone, email, etc) as the first row with that row. For the record, I'm using the Django framework for my back-end code. What's the best approach here? Should it just POST the form x times for x people, or is there a less "brute force" way of handling this?

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  • Declaring models elsewhere than in "models.py" AND dynamically

    - by sebpiq
    Hi ! I have an application that splits models into different files. Actually the folder looks like : >myapp __init__.py models.py >hooks ... ... myapp don't care about what's in the hooks, folder, except that there are models, and that they have to be declared somehow. So, I put this in myapp.__init__.py : from django.conf import settings for hook in settings.HOOKS : try : __import__(hook) except ImportError as e : print "Got import err !", e #where settings.HOOKS = ("myapp.hooks.a_super_hook1", ...) The problem is that it doesn't work when I run syncdb(and throws some strange "Got import err !"... strange considering that it's related to another module of my program that I don't even import anywhere :/ ) ! So I tried successively : 1) for hook in settings.HOOKS : try : exec ("from %s import *" % hook) - doesn't work either : syncdb doesn't install the models in hooks 2) from myapp.hooks.a_super_hook1 import * - This works 3) exec("from myapp.hooks.a_super_hook1 import *") - This works to So I checked that in the test 1), the statement executed is the same than in tests 2) and 3), and it is exactly the same ... Any idea ???

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  • Guidance on E-commerce in a Python Framework

    - by Ant
    I am looking for guidance in making decisions on using Python for E-commerce. My reasoning to use Python in the first place is i do a lot of 3D so it's a real help to use Python for web server side as well as 3D so I do not need to learn a new language. When I say E-commerce i mean the logic behind displaying products and a check out system that is Robust....and yes I really want to build this myself so I can change it. I do not want to use an out the box solution that costs a lot of money every month. I want control of server side, data bases, e-commerce etc. My questions are: What Frameworks are out there? I looked at previous questions on stackoverflow but only found old posts about Sachmo and Get paid. What is the learning path, I do not want to make a mistake that costs six months of studying? Python then Django? How long if I spent 10 hours a day studying this would it take to get up and running? I write javaScript badly, so I am not a complete noob, I understand the basics of programming languages. many thanks in advance

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  • Spring's EntityManager not persisting

    - by Fernando Camargo
    Well, my project was using EJB and JPA (with Hibernate), but I had to switch to Spring. Everything was working well before that. The EJB used to inject the EntityManager, controled the transaction, etc. Ok, when I switched to Spring, I had a lot of problems because I'm new on Spring. But after everything is running, I have the problem: the data is never saved on database. I configured my Spring to control the transactions, I have spring beans used in JSF, that has spring services that do the hard work. This services have a EntityManager injected and use @Transactional REQUIRED. This services pass the EntityManager to a DAO that call entityManager.persist(bean). The selects appears to work well, the JTA transaction appears to work well to (I saw in log), but the entity is not saved! Here is the log: INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter: doFilterInternal() (linha 136): Opening JPA EntityManager in OpenEntityManagerInViewFilter INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory: doGetBean() (linha 245): Returning cached instance of singleton bean 'transactionManager' INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: getTransaction() (linha 365): Creating new transaction with name [br.org.cni.pronatec.controller.service.MontanteServiceImpl.adicionarValor]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT; '' INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 493): Opened new Session [org.hibernate.impl.SessionImpl@2b2fe2f0] for Hibernate transaction INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 504): Preparing JDBC Connection of Hibernate Session [org.hibernate.impl.SessionImpl@2b2fe2f0] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doBegin() (linha 569): Exposing Hibernate transaction as JDBC transaction [com.sun.gjc.spi.jdbc40.ConnectionHolder40@3bcd4840] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler: doJoinTransaction() (linha 383): Joined JTA transaction INFO: Hibernate: select hibernate_sequence.nextval from dual INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: processCommit() (linha 752): Initiating transaction commit INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doCommit() (linha 652): Committing Hibernate transaction on Session [org.hibernate.impl.SessionImpl@2b2fe2f0] INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.HibernateTransactionManager: doCleanupAfterCompletion() (linha 734): Closing Hibernate Session [org.hibernate.impl.SessionImpl@2b2fe2f0] after transaction INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.hibernate3.SessionFactoryUtils: closeSession() (linha 800): Closing Hibernate Session INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter: doFilterInternal() (linha 154): Closing JPA EntityManager in OpenEntityManagerInViewFilter INFO: [Pronatec] - 04/04/2012 11:30:20 - [DEBUG] org.springframework.orm.jpa.EntityManagerFactoryUtils: closeEntityManager() (linha 343): Closing JPA EntityManager In the log, I see it commiting the transaction, but I don't see the insert query (the Hibernate is printing any query). I also see that the Hibernate lookup to get the next value of the sequence ID. But after that, it never really inserts. Here is the spring context configuration: <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="PronatecPU" /> <property name="persistenceXmlLocation" value="classpath:META-INF/persistence.xml" /> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver"/> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" > <property name="transactionManagerName" value="java:/TransactionManager" /> <property name="userTransactionName" value="UserTransaction" /> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> <tx:annotation-driven transaction-manager="transactionManager" /> Here is my persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="PronatecPU" transaction-type="JTA"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>jdbc/pronatec</jta-data-source> <class>br.org.cni.pronatec.model.bean.AgendamentoBuscaSistec</class> <class>br.org.cni.pronatec.model.bean.AgendamentoExportacaoZeus</class> <class>br.org.cni.pronatec.model.bean.AgendamentoImportacaoZeus</class> <class>br.org.cni.pronatec.model.bean.Aluno</class> <class>br.org.cni.pronatec.model.bean.Curso</class> <class>br.org.cni.pronatec.model.bean.DepartamentoRegional</class> <class>br.org.cni.pronatec.model.bean.Dof</class> <class>br.org.cni.pronatec.model.bean.Escola</class> <class>br.org.cni.pronatec.model.bean.Inconsistencia</class> <class>br.org.cni.pronatec.model.bean.Matricula</class> <class>br.org.cni.pronatec.model.bean.Montante</class> <class>br.org.cni.pronatec.model.bean.ParametrosVingentes</class> <class>br.org.cni.pronatec.model.bean.TipoCurso</class> <class>br.org.cni.pronatec.model.bean.Turma</class> <class>br.org.cni.pronatec.model.bean.UnidadeFederativa</class> <class>br.org.cni.pronatec.model.bean.ValorAssistenciaEstudantil</class> <class>br.org.cni.pronatec.model.bean.ValorHora</class> <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <property name="current_session_context_class" value="thread"/> <property name="hibernate.show_sql" value="true"/> <property name="hibernate.format_sql" value="true"/> <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect"/> <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.SunONETransactionManagerLookup"/> <property name="hibernate.hbm2ddl.auto" value="update"/> </properties> </persistence-unit> </persistence> Here is my service that is injected in the managed bean: @Service @Scope("prototype") @Transactional(propagation= Propagation.REQUIRED) public class MontanteServiceImpl { // more code @PersistenceContext(unitName="PronatecPU", type= PersistenceContextType.EXTENDED) private EntityManager entityManager; // more code // The method that is called by another public method that do something before private void salvarMontante(Montante montante) { montante.setDataTransacao(new Date()); MontanteDao montanteDao = new MontanteDao(entityManager); montanteDao.salvar(montante); } // more code } My MontanteDao inherits from a base DAO, like this: public class MontanteDao extends BaseDao<Montante> { public MontanteDao(EntityManager entityManager) { super(entityManager); } } And the method that is called in BaseDao is this: public void salvar(T bean) { entityManager.persist(bean); } Like you can see, it just pick the injected entityManager and call the persist() method. The transaction is being controlled by the Spring, like is printed in the log, but the insert query is never printed in log and it is never saved. I'm sorry about my bad english. Thanks in advance for who helps.

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  • A first look at ConfORM - Part 1

    - by thangchung
    All source codes for this post can be found at here.Have you ever heard of ConfORM is not? I have read it three months ago when I wrote an post about NHibernate and Autofac. At that time, this project really has just started and still in beta version, so I still do not really care much. But recently when reading a book by Jason Dentler NHibernate 3.0 Cookbook, I started to pay attention to it. Author have mentioned quite a lot of OSS in his book. And now again I have reviewed ConfORM once again. I have been involved in ConfORM development group on google and read some articles about it. Fabio Maulo spent a lot of work for the OSS, and I hope it will adapt a great way for NHibernate (because he contributed to NHibernate that). So what is ConfORM? It is stand for Configuration ORM, and it was trying to use a lot of heuristic model for identifying entities from C# code. Today, it's mostly Model First Driven development, so the first thing is to build the entity model. This is really important and we can see it is the heart of business software. Then we have to tell DB about the entity of this model. We often will use Inversion Engineering here, Database Schema is will create based on recently Entity Model. From now we will absolutely not interested in the DB again, only focus on the Entity Model.Fluent NHibenate really good, I liked this OSS. Sharp Architecture and has done so well in Fluent NHibernate integration with applications. A Multiple Database technical in Sharp Architecture is truly awesome. It can receive configuration, a connection string and a dll containing entity model, which would then create a SessionFactory, finally caching inside the computer memory. As the number of SessionFactory can be very large and will full of the memory, it has also devised a way of caching SessionFactory in the file. This post I hope this will not completely explain about and building a model of multiple databases. I just tried to mount a number of posts from the community and apply some of my knowledge to build a management model Session for ConfORM.As well as Fluent NHibernate, ConfORM also supported on the interface mapping, see this to understand it. So the first thing we will build the Entity Model for it, and here is what I will use the model for this article. A simple model for managing news and polls, it will be too easy for a number of people, but I hope not to bring complexity to this post.I will then have some code to build super type for the Entity Model. public interface IEntity<TId>    {        TId Id { get; set; }    } public abstract class EntityBase<TId> : IEntity<TId>    {        public virtual TId Id { get; set; }         public override bool Equals(object obj)        {            return Equals(obj as EntityBase<TId>);        }         private static bool IsTransient(EntityBase<TId> obj)        {            return obj != null &&            Equals(obj.Id, default(TId));        }         private Type GetUnproxiedType()        {            return GetType();        }         public virtual bool Equals(EntityBase<TId> other)        {            if (other == null)                return false;            if (ReferenceEquals(this, other))                return true;            if (!IsTransient(this) &&            !IsTransient(other) &&            Equals(Id, other.Id))            {                var otherType = other.GetUnproxiedType();                var thisType = GetUnproxiedType();                return thisType.IsAssignableFrom(otherType) ||                otherType.IsAssignableFrom(thisType);            }            return false;        }         public override int GetHashCode()        {            if (Equals(Id, default(TId)))                return base.GetHashCode();            return Id.GetHashCode();        }    } Database schema will be created as:The next step is to build the ConORM builder to create a NHibernate Configuration. Patrick have a excellent article about it at here. Contract of it below: public interface IConfigBuilder    {        Configuration BuildConfiguration(string connectionString, string sessionFactoryName);    } The idea here is that I will pass in a connection string and a set of the DLL containing the Entity Model and it makes me a NHibernate Configuration (shame that I stole this ideas of Sharp Architecture). And here is its code: public abstract class ConfORMConfigBuilder : RootObject, IConfigBuilder    {        private static IConfigurator _configurator;         protected IEnumerable<Type> DomainTypes;         private readonly IEnumerable<string> _assemblies;         protected ConfORMConfigBuilder(IEnumerable<string> assemblies)            : this(new Configurator(), assemblies)        {            _assemblies = assemblies;        }         protected ConfORMConfigBuilder(IConfigurator configurator, IEnumerable<string> assemblies)        {            _configurator = configurator;            _assemblies = assemblies;        }         public abstract void GetDatabaseIntegration(IDbIntegrationConfigurationProperties dBIntegration, string connectionString);         protected abstract HbmMapping GetMapping();         public Configuration BuildConfiguration(string connectionString, string sessionFactoryName)        {            Contract.Requires(!string.IsNullOrEmpty(connectionString), "ConnectionString is null or empty");            Contract.Requires(!string.IsNullOrEmpty(sessionFactoryName), "SessionFactory name is null or empty");            Contract.Requires(_configurator != null, "Configurator is null");             return CatchExceptionHelper.TryCatchFunction(                () =>                {                    DomainTypes = GetTypeOfEntities(_assemblies);                     if (DomainTypes == null)                        throw new Exception("Type of domains is null");                     var configure = new Configuration();                    configure.SessionFactoryName(sessionFactoryName);                     configure.Proxy(p => p.ProxyFactoryFactory<ProxyFactoryFactory>());                    configure.DataBaseIntegration(db => GetDatabaseIntegration(db, connectionString));                     if (_configurator.GetAppSettingString("IsCreateNewDatabase").ConvertToBoolean())                    {                        configure.SetProperty("hbm2ddl.auto", "create-drop");                    }                     configure.Properties.Add("default_schema", _configurator.GetAppSettingString("DefaultSchema"));                    configure.AddDeserializedMapping(GetMapping(),                                                     _configurator.GetAppSettingString("DocumentFileName"));                     SchemaMetadataUpdater.QuoteTableAndColumns(configure);                     return configure;                }, Logger);        }         protected IEnumerable<Type> GetTypeOfEntities(IEnumerable<string> assemblies)        {            var type = typeof(EntityBase<Guid>);            var domainTypes = new List<Type>();             foreach (var assembly in assemblies)            {                var realAssembly = Assembly.LoadFrom(assembly);                 if (realAssembly == null)                    throw new NullReferenceException();                 domainTypes.AddRange(realAssembly.GetTypes().Where(                    t =>                    {                        if (t.BaseType != null)                            return string.Compare(t.BaseType.FullName,                                          type.FullName) == 0;                        return false;                    }));            }             return domainTypes;        }    } I do not want to dependency on any RDBMS, so I made a builder as an abstract class, and so I will create a concrete instance for SQL Server 2008 as follows: public class SqlServerConfORMConfigBuilder : ConfORMConfigBuilder    {        public SqlServerConfORMConfigBuilder(IEnumerable<string> assemblies)            : base(assemblies)        {        }         public override void GetDatabaseIntegration(IDbIntegrationConfigurationProperties dBIntegration, string connectionString)        {            dBIntegration.Dialect<MsSql2008Dialect>();            dBIntegration.Driver<SqlClientDriver>();            dBIntegration.KeywordsAutoImport = Hbm2DDLKeyWords.AutoQuote;            dBIntegration.IsolationLevel = IsolationLevel.ReadCommitted;            dBIntegration.ConnectionString = connectionString;            dBIntegration.LogSqlInConsole = true;            dBIntegration.Timeout = 10;            dBIntegration.LogFormatedSql = true;            dBIntegration.HqlToSqlSubstitutions = "true 1, false 0, yes 'Y', no 'N'";        }         protected override HbmMapping GetMapping()        {            var orm = new ObjectRelationalMapper();             orm.Patterns.PoidStrategies.Add(new GuidPoidPattern());             var patternsAppliers = new CoolPatternsAppliersHolder(orm);            //patternsAppliers.Merge(new DatePropertyByNameApplier()).Merge(new MsSQL2008DateTimeApplier());            patternsAppliers.Merge(new ManyToOneColumnNamingApplier());            patternsAppliers.Merge(new OneToManyKeyColumnNamingApplier(orm));             var mapper = new Mapper(orm, patternsAppliers);             var entities = new List<Type>();             DomainDefinition(orm);            Customize(mapper);             entities.AddRange(DomainTypes);             return mapper.CompileMappingFor(entities);        }         private void DomainDefinition(IObjectRelationalMapper orm)        {            orm.TablePerClassHierarchy(new[] { typeof(EntityBase<Guid>) });            orm.TablePerClass(DomainTypes);             orm.OneToOne<News, Poll>();            orm.ManyToOne<Category, News>();             orm.Cascade<Category, News>(Cascade.All);            orm.Cascade<News, Poll>(Cascade.All);            orm.Cascade<User, Poll>(Cascade.All);        }         private static void Customize(Mapper mapper)        {            CustomizeRelations(mapper);            CustomizeTables(mapper);            CustomizeColumns(mapper);        }         private static void CustomizeRelations(Mapper mapper)        {        }         private static void CustomizeTables(Mapper mapper)        {        }         private static void CustomizeColumns(Mapper mapper)        {            mapper.Class<Category>(                cm =>                {                    cm.Property(x => x.Name, m => m.NotNullable(true));                    cm.Property(x => x.CreatedDate, m => m.NotNullable(true));                });             mapper.Class<News>(                cm =>                {                    cm.Property(x => x.Title, m => m.NotNullable(true));                    cm.Property(x => x.ShortDescription, m => m.NotNullable(true));                    cm.Property(x => x.Content, m => m.NotNullable(true));                });             mapper.Class<Poll>(                cm =>                {                    cm.Property(x => x.Value, m => m.NotNullable(true));                    cm.Property(x => x.VoteDate, m => m.NotNullable(true));                    cm.Property(x => x.WhoVote, m => m.NotNullable(true));                });             mapper.Class<User>(                cm =>                {                    cm.Property(x => x.UserName, m => m.NotNullable(true));                    cm.Property(x => x.Password, m => m.NotNullable(true));                });        }    } As you can see that we can do so many things in this class, such as custom entity relationships, custom binding on the columns, custom table name, ... Here I only made two so-Appliers for OneToMany and ManyToOne relationships, you can refer to it here public class ManyToOneColumnNamingApplier : IPatternApplier<PropertyPath, IManyToOneMapper>    {        #region IPatternApplier<PropertyPath,IManyToOneMapper> Members         public void Apply(PropertyPath subject, IManyToOneMapper applyTo)        {            applyTo.Column(subject.ToColumnName() + "Id");        }         #endregion         #region IPattern<PropertyPath> Members         public bool Match(PropertyPath subject)        {            return subject != null;        }         #endregion    } public class OneToManyKeyColumnNamingApplier : OneToManyPattern, IPatternApplier<PropertyPath, ICollectionPropertiesMapper>    {        public OneToManyKeyColumnNamingApplier(IDomainInspector domainInspector) : base(domainInspector) { }         #region Implementation of IPattern<PropertyPath>         public bool Match(PropertyPath subject)        {            return Match(subject.LocalMember);        }         #endregion Implementation of IPattern<PropertyPath>         #region Implementation of IPatternApplier<PropertyPath,ICollectionPropertiesMapper>         public void Apply(PropertyPath subject, ICollectionPropertiesMapper applyTo)        {            applyTo.Key(km => km.Column(GetKeyColumnName(subject)));        }         #endregion Implementation of IPatternApplier<PropertyPath,ICollectionPropertiesMapper>         protected virtual string GetKeyColumnName(PropertyPath subject)        {            Type propertyType = subject.LocalMember.GetPropertyOrFieldType();            Type childType = propertyType.DetermineCollectionElementType();            var entity = subject.GetContainerEntity(DomainInspector);            var parentPropertyInChild = childType.GetFirstPropertyOfType(entity);            var baseName = parentPropertyInChild == null ? subject.PreviousPath == null ? entity.Name : entity.Name + subject.PreviousPath : parentPropertyInChild.Name;            return GetKeyColumnName(baseName);        }         protected virtual string GetKeyColumnName(string baseName)        {            return string.Format("{0}Id", baseName);        }    } Everyone also can download the ConfORM source at google code and see example inside it. Next part I will write about multiple database factory. Hope you enjoy about it. happy coding and see you next part.

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  • sudo apt-get install python.pip python-dev Gives Error

    - by user2539745
    I am learning Django from http://gettingstartedwithdjango.com/ and I have windows 7 32-bit. The tutorial asked to install virtualbox and vagrant(tutorial had precise64 and it had issues in my pc so I installed precise32) so I did it. Now the tutorial asked to do sudo apt-get install python-dev python.pip so I did it but it gave me this error > vagrant@precise32:~$ sudo apt-get install python.pip python-dev Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'python-pip' for regex 'python.pip' Note, selecting 'python-pipeline' for regex 'python.pip' The following extra packages will be installed: libexpat1 libexpat1-dev libpython2.7 python-pkg-resources python-setuptools python-support python2.7 python2.7-dev python2.7-minimal Suggested packages: python-distribute python-distribute-doc python2.7-doc binfmt-support The following NEW packages will be installed: libexpat1-dev libpython2.7 python-dev python-pip python-pipeline python-pkg-resources python-setuptools python-support python2.7-dev The following packages will be upgraded: libexpat1 python2.7 python2.7-minimal 3 upgraded, 9 newly installed, 0 to remove and 63 not upgraded. Need to get 34.7 MB/35.7 MB of archives. After this operation, 42.0 MB of additional disk space will be used. Do you want to continue [Y/n]? y Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7 i386 2.7 .3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7-minimal i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main libpython2.7 i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7-dev i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7-minimal_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/libpyt hon2.7_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7-dev_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-mis sing? Please help what should I do ??

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  • System architecture: simple approach for setting up background tasks behind a web application -- wil

    - by Tim Molendijk
    I have a Django web application and I have some tasks that should operate (or actually: be initiated) on the background. The application is deployed as follows: apache2-mpm-worker; mod_wsgi in daemon mode (1 process, 15 threads). The background tasks have the following characteristics: they need to operate in a regular interval (every 5 minutes or so); they require the application context (i.e. the application packages need to be available in memory); they do not need any input other than database access, in order to perform some not-so-heavy tasks such as sending out e-mail and updating the state of the database. Now I was thinking that the most simple approach to this problem would be simply to piggyback on the existing application process (as spawned by mod_wsgi). By implementing the task as part of the application and providing an HTTP interface for it, I would prevent the overhead of another process that is holding all of the application into memory. A simple cronjob can be setup that sends a request to this HTTP interface every 5 minutes and that would be it. Since the application process provides 15 threads and the tasks are quite lightweight and only running every 5 minutes, I figure they would not be hindering the performance of the web application's user-facing operations. Yet... I have done some online research and I have seen nobody advocating this approach. Many articles suggest a significantly more complex approach based on a full-blown messaging component (such as Celery, which uses RabbitMQ). Although that's sexy, it sounds like overkill to me. Some articles suggest setting up a cronjob that executes a script which performs the tasks. But that doesn't feel very attractive either, as it results in creating a new process that loads the entire application into memory, performs some tiny task, and destroys the process again. And this is repeated every 5 minutes. Does not sound like an elegant solution. So, I'm looking for some feedback on my suggested approach as described in the paragraph before the preceeding paragraph. Is my reasoning correct? Am I overlooking (potential) problems? What about my assumption that application's performance will not be impeded?

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  • Keeping files or database records? Java and Python

    - by danpalmer
    My website will use a Neural Network to predict thing based on user data. The user can select the data to be used in training the network and then use their trained network to predict things. I am using a framework to create, train and query the networks. This uses Java. The framework has persistence for saving a network to an XML file. What is the best way to store these files? I can see several potential ideas, but I need help on choosing which is best: Save each network to a separate XML file with a name that is stored in the database. Load this each time. Save all the networks to the same XML file with each network having a different name that is stored in the database. Somehow pass what would normally be written to an XML file to the Django site for writing to the database. This would need to be returned to the Java code when a prediction needs to be made. I am able to do 1 or 2, but I think their performance will be quite limited and I am on shared hosting at the moment, so I don't know how pleased they would be with thousands of files. Also, after adding a few thousand records to one XML file, I was noticing a massive performance hit on saving to it. If I were able to implement version 3 somehow I think it would be best. No issues with separate processes accessing the database and I think performance would be better. Not to mention having no files lying around. However, the stuff in the neural network framework I am using (Encog) for saving to a file needs access to a Java file object, not a string that could be saved to a database. Unless there is some Java magic I can do here (I know very little Java), the only way I can see of doing this would be with a temporary files but I don't know if this is the correct way to do it. I would appreciate any ideas on the best way to implement any of the above 3 ideas or any alternatives. Thanks!

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  • Which StackOverflow-style MarkDown (WMD) javascript editor should I use?

    - by Edan Maor
    Background I'm working on an application which requires user-entered content, and I've decided to use a StackOverflow-style MarkDown editor. After researching this topic for the last few days, I realize there are numerous forks of the base WMD editor, some with a few basic enhancements and some with serious differences from the StackOverflow one. Since this will be the heart of the application, I'd like to start with the best code base I can. I'd be happy if anyone can recommend which one of the many solutions out there best fits my needs. Below is requirements, plus what I've managed to find already. I'm hoping this question will help me decide which version to go with, and maybe help me discover a port out there that's an even better fit for my needs. The requirements for my project Live Preview Multiple editors on the same page (not know how many in advance, since the user can dynamically add another editing box). Ability to extend with extra buttons (I'd like a button to upload a picture, instead of just adding an img url). Ability to dynamically show/hide the edit box (and only see the preview box). Not an absolute must, but I'd prefer to stick as close to StackOverflow's look and feel, since it's well known. Don't know if this matters, but the backend is written in Django. Editors I've looked at Here are a few of the code bases I've looked at, with thoughts. Obviously, I might be missing another solution out there. The derobins version. From what I can tell, this is the official StackOverflow version. Seems like it doesn't support multiple editors on one page. JQuery.MarkEdit. Looks very good, but is pretty different from the StackOverflow version. MooWMD. Looks like the winner right now, but I'm a little concerned since it looks less active/hackable than MarkEdit. The wmd-new version. Not sure, looks like an old codebase without much use. The SocialSite branch. Seems like it's not for public use.

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  • Which MarkDown (WMD) javascript editor should I use?

    - by Edan Maor
    Background I'm working on an application which requires user-entered content, and I've decided to use a StackOverflow-style MarkDown editor. After researching this topic for the last few days, I realize there are numerous forks of the base WMD editor, some with a few basic enhancements and some with serious differences from the StackOverflow one. Since this will be the heart of the application, I'd like to start with the best code base I can. I'd be happy if anyone can recommend which one of the many solutions out there best fits my needs. Below is requirements, plus what I've managed to find already. I'm hoping this question will help me decide which version to go with, and maybe help me discover a port out there that's an even better fit for my needs. The requirements for my project Live Preview Multiple editors on the same page (not know how many in advance, since the user can dynamically add another editing box). Ability to extend with extra buttons (I'd like a button to upload a picture, instead of just adding an img url). Ability to dynamically show/hide the edit box (and only see the preview box). Not an absolute must, but I'd prefer to stick as close to StackOverflow's look and feel, since it's well known. Don't know if this matters, but the backend is written in Django. Editors I've looked at Here are a few of the code bases I've looked at, with thoughts. Obviously, I might be missing another solution out there. The derobins version. From what I can tell, this is the official StackOverflow version. Seems like it doesn't support multiple editors on one page. JQuery.MarkEdit. Looks very good, but is pretty different from the StackOverflow version. MooWMD. Looks like the winner right now, but I'm a little concerned since it looks less active/hackable than MarkEdit. The wmd-new version. Not sure, looks like an old codebase without much use. The SocialSite branch. Seems like it's not for public use.

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  • Dynamic mass hosting using mod_wsgi

    - by Virgil Balibanu
    Hi, I am trying to configure an apache server using mod_wsgi for dynamic mass hosting. Each user will have it's own instance of a python application located in /mnt/data/www/domains/[user_name] and there will be a vhost.map telling me which domain maps to each user's directory (the directory will have the same name as the user). What i do not know is how to write the WSGIScriptAliasMatch line so that it also takes the path from the vhost.map file. What i want to do is something like this: I can have on my server different domains like www.virgilbalibanu.com or virgil.balibanu.com and flaviu.balibanu.com where each domain would belog to another user, the user name having no neccesary connection to the domain name. I want to do this beacuse a user, wehn he makes an acoount receives something like virgil.mydomain.com but if he has his own domain he can change it later to that, for example www.virgilbalibanu.ro, and this way I would only need to chenage the line in the vhost.map file So far I have something like this: Alias /media/ /mnt/data/www/iitcms/media/ #all media is taken from here RewriteEngine on RewriteMap lowercase int:tolower # define the map file RewriteMap vhost txt:/mnt/data/www/domains/vhost.map #this does not work either, can;t say why atm RewriteCond %{REQUEST_URI} ^/uploads/ RewriteCond ${lowercase:%{SERVER_NAME}} ^(.+)$ RewriteCond ${vhost:%1} ^(/.*)$ RewriteRule ^/(.*)$ %1/media/uploads/$1 #---> this I have no ideea how i could do WSGIScriptAliasMatch ^([^/]+) /mnt/data/www/domains/$1/apache/django.wsgi <Directory "/mnt/data/www/domains"> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny Allow from all </Directory> <DirectoryMatch ^/mnt/data/www/domains/([^/]+)/apache> AllowOverride None Options FollowSymLinks ExecCGI Order deny,allow Allow from all </DirectoryMatch> <Directory /mnt/data/www/iitcms/media> AllowOverride None Options Indexes FollowSymLinks MultiViews Order allow,deny Allow from all </Directory> <DirectoryMatch ^/mnt/data/www/domains/([^/]+)/media/uploads> AllowOverride None Options Indexes FollowSymLinks MultiViews Order allow,deny Allow from all </DirectoryMatch> I know the part i did with mod_rewrite doesn't work, couldn't really say why not but that's not as important so far, I am curious how could i write the WSGIScriptAliasMatch line so that to accomplish my objective. I would be very grateful for any help, or any other ideas related to how i can deal with this. Also it would be great if I'd manage to get each site to run in wsgi daemon mode, thou that is not as important. Thanks, Virgil

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  • Speeding up templates in GAE-Py by aggregating RPC calls

    - by Sudhir Jonathan
    Here's my problem: class City(Model): name = StringProperty() class Author(Model): name = StringProperty() city = ReferenceProperty(City) class Post(Model): author = ReferenceProperty(Author) content = StringProperty() The code isn't important... its this django template: {% for post in posts %} <div>{{post.content}}</div> <div>by {{post.author.name}} from {{post.author.city.name}}</div> {% endfor %} Now lets say I get the first 100 posts using Post.all().fetch(limit=100), and pass this list to the template - what happens? It makes 200 more datastore gets - 100 to get each author, 100 to get each author's city. This is perfectly understandable, actually, since the post only has a reference to the author, and the author only has a reference to the city. The __get__ accessor on the post.author and author.city objects transparently do a get and pull the data back (See this question). Some ways around this are Use Post.author.get_value_for_datastore(post) to collect the author keys (see the link above), and then do a batch get to get them all - the trouble here is that we need to re-construct a template data object... something which needs extra code and maintenance for each model and handler. Write an accessor, say cached_author, that checks memcache for the author first and returns that - the problem here is that post.cached_author is going to be called 100 times, which could probably mean 100 memcache calls. Hold a static key to object map (and refresh it maybe once in five minutes) if the data doesn't have to be very up to date. The cached_author accessor can then just refer to this map. All these ideas need extra code and maintenance, and they're not very transparent. What if we could do @prefetch def render_template(path, data) template.render(path, data) Turns out we can... hooks and Guido's instrumentation module both prove it. If the @prefetch method wraps a template render by capturing which keys are requested we can (atleast to one level of depth) capture which keys are being requested, return mock objects, and do a batch get on them. This could be repeated for all depth levels, till no new keys are being requested. The final render could intercept the gets and return the objects from a map. This would change a total of 200 gets into 3, transparently and without any extra code. Not to mention greatly cut down the need for memcache and help in situations where memcache can't be used. Trouble is I don't know how to do it (yet). Before I start trying, has anyone else done this? Or does anyone want to help? Or do you see a massive flaw in the plan?

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  • How does Sentry aggregate errors?

    - by Hugo Rodger-Brown
    I am using Sentry (in a django project), and I'd like to know how I can get the errors to aggregate properly. I am logging certain user actions as errors, so there is no underlying system exception, and am using the culprit attribute to set a friendly error name. The message is templated, and contains a common message ("User 'x' was unable to perform action because 'y'"), but is never exactly the same (different users, different conditions). Sentry clearly uses some set of attributes under the hood to determine whether to aggregate errors as the same exception, but despite having looked through the code, I can't work out how. Can anyone short-cut my having to dig further into the code and tell me what properties I need to set in order to manage aggregation as I would like? [UPDATE 1: event grouping] This line appears in sentry.models.Group: class Group(MessageBase): """ Aggregated message which summarizes a set of Events. """ ... class Meta: unique_together = (('project', 'logger', 'culprit', 'checksum'),) ... Which makes sense - project, logger and culprit I am setting at the moment - the problem is checksum. I will investigate further, however 'checksum' suggests that binary equivalence, which is never going to work - it must be possible to group instances of the same exception, with differenct attributes? [UPDATE 2: event checksums] The event checksum comes from the sentry.manager.get_checksum_from_event method: def get_checksum_from_event(event): for interface in event.interfaces.itervalues(): result = interface.get_hash() if result: hash = hashlib.md5() for r in result: hash.update(to_string(r)) return hash.hexdigest() return hashlib.md5(to_string(event.message)).hexdigest() Next stop - where do the event interfaces come from? [UPDATE 3: event interfaces] I have worked out that interfaces refer to the standard mechanism for describing data passed into sentry events, and that I am using the standard sentry.interfaces.Message and sentry.interfaces.User interfaces. Both of these will contain different data depending on the exception instance - and so a checksum will never match. Is there any way that I can exclude these from the checksum calculation? (Or at least the User interface value, as that has to be different - the Message interface value I could standardise.) [UPDATE 4: solution] Here are the two get_hash functions for the Message and User interfaces respectively: # sentry.interfaces.Message def get_hash(self): return [self.message] # sentry.interfaces.User def get_hash(self): return [] Looking at these two, only the Message.get_hash interface will return a value that is picked up by the get_checksum_for_event method, and so this is the one that will be returned (hashed etc.) The net effect of this is that the the checksum is evaluated on the message alone - which in theory means that I can standardise the message and keep the user definition unique. I've answered my own question here, but hopefully my investigation is of use to others having the same problem. (As an aside, I've also submitted a pull request against the Sentry documentation as part of this ;-)) (Note to anyone using / extending Sentry with custom interfaces - if you want to avoid your interface being use to group exceptions, return an empty list.)

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