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  • insertRecord into QSqlTableModel fails, but item appears in QListView

    - by Anteru
    I got a pretty weird problem with a QSqlTableModel. The underlying SQL Database has a constraint Title UNIQUE. If I add a record which violates the constraint using insertRecord, the call fails (return value is false.) However, the view which uses the model displays the entry -- I have to manually remove it in order to get rid of it. How can I change this so the view does not get updated when an insertRecord fails? I would have assumed that the view gets only updated if there is really a change ...

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  • Database Design Primay Key, ID vs String

    - by LnDCobra
    Hi, I am currently planning to develop a music streaming application. And i am wondering what would be better as a primary key in my tables on the server. An ID int or a Unique String. Methods 1: Songs Table: SongID(int), Title(string), Artist*(string), Length(int), Album*(string) Genre Table Genre(string), Name(string) SongGenre: SongID*(int), Genre*(string) Method 2 Songs Table: SongID(int), Title(string), ArtistID*(int), Length(int), AlbumID*(int) Genre Table GenreID(int), Name(string) SongGenre: SongID*(int), GenreID*(int) Key: Bold = Primary Key, Field* = Foreign Key I'm currently designing using method 2 as I believe it will speed up lookup performance and use less space as an int takes a lot less space then a string. Is there any reason this isn't a good idea? Is there anything I should be aware of?

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  • Using boost unordered map

    - by Amrish
    Guys, I am using dynamic programming approach to solve a problem. Here is a brief overview of the approach Each value generated is identified using 25 unique keys. I use the boost::hash_combine to generate the seed for the hash table using these 25 keys. I store the values in a hash table declared as boost::unordered_map<Key_Object, Data_Object, HashFunction> hashState; I did a time profiling on my algorithm and found that nearly 95% of the run time is spent towards retrieving/inserting data into the hash table. These were the details of my hash table hashState.size() 1880 hashState.load_factor() 0.610588 hashState.bucket_count() 3079 hashState.max_size() 805306456 hashState.max_load_factor() 1 hashState.max_bucket_count() 805306457 I have the following two questions Is there anything which I can do to improve the performance of the Hash Table's insert/retrieve operations? C++ STL has hash_multimap which would also suit my requirement. How does boost libraries unordered_map compare with hash_multimap in terms of insert/retrieve performance.

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  • Machine Learning Algorithm for Peer-to-Peer Nodes

    - by FreshCode
    I want to apply machine learning to a classification problem in a parallel environment. Several independent nodes, each with multiple on/off sensors, can communicate their sensor data with the goal of classifying an event as defined by a heuristic, training data or both. Each peer will be measuring the same data from their unique perspective and will attempt to classify the result while taking into account that any neighbouring node (or its sensors or just the connection to the node) could be faulty. Nodes should function as equal peers and determine the most likely classification by communicating their results. Ultimately each node should make a decision based on their own sensor data and their peers' data. If it matters, false positives are OK for certain classifications (albeit undesirable) but false negatives would be totally unacceptable. Given that each final classification will receive good or bad feedback, what would be an appropriate machine learning algorithm to approach this problem with if the nodes could communicate with each other to determine the most likely classification?

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  • Load Ruby on Rails models without loading the entire framework

    - by epochwolf
    I'm looking to create a custom daemon that will run various database tasks such as delaying mailings and user notifications (each notice is a separate row in the notifications table). I don't want to use script/runner or rake to do these tasks because it is possible that some of the tasks only require the create of one or two database rows or thousands of rows depending on the task. I don't want the overhead of launching a ruby process or loading the entire rails framework for each operation. I plan to keep this daemon in memory full time. To create this daemon I would like to use my models from my ruby on rails application. I have a number of rails plugins such as acts_as_tree and AASM that I will need loaded if I where to use the models. Some of the plugins I need to load are custom hacks on ActiveRecord::Base that I've created. (I am willing to accept removing or recoding some of the plugins if they need components from other parts of rails.) My questions are Is this a good idea? And - Is this possible to do in a way that doesn't have me manually including each file in my models and plugins? If not a good idea What is a good alternative? (I am not apposed to doing writing my own SQL queries but I would have to add database constraints and a separate user for the daemon to prevent any stupid accidents. Given my lack of familiarity with configuring a database, I would like to use active record as a crutch.)

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  • Why is my logic not working correctly for SPOJ TOPOSORT?

    - by Kavish Dwivedi
    The given problem is http://www.spoj.com/problems/TOPOSORT/ The output format is particularly important as : Print "Sandro fails." if Sandro cannot complete all his duties on the list. If there is a solution print the correct ordering, the jobs to be done separated by a whitespace. If there are multiple solutions print the one, whose first number is smallest, if there are still multiple solutions, print the one whose second number is smallest, and so on. What I am doing is simply doing dfs by reversing the edges i.e if job A finishes before job B, there is a directed edge from B to A . I am maintaining the order by sorting the adjacency list I created and storing the nodes which don't have any constraints separately so as to print them later in correct order . There are two flag arrays used , one for marking discovered node and one for marking the node whose all neighbors have been explored. Now my solution is http://www.ideone.com/QCUmKY (the important function is the visit funtion ) and its giving WA after running correct for 10 cases so its really hard to figure out where am I doing it wrong since it runs for all of the test cases which I have done by hand.

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  • Tuples of unknown size/parameter types

    - by myahya
    I need to create a map, from integers to sets of tuples, the tuples in a single set have the same size. The problem is that the size of a tuple and its parameter types can be determined at runtime, not compile time. I am imagining something like: std::map<int, std::set<boost::tuple> > but not exctly sure how to exactly do this, bossibly using pointers. The purpose of this is to create temporary relations (tables), each with a unique identifier (key), maybe you have another approach.

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  • SQL model optimization question

    - by supermogx
    I need to keep track of number of "hits" on a particular item in a DB. The thing is that the "hits" should stay unique with a user ID, so if a user hits the item 3 times, it should still count for a hit of 1. Also, I need to display the total number of hits for a particular item. Is there a better way than to store each hits for each items by each users in a separate table? Would keeping the user ID in a string separated by commas a better and efficient way?

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  • SQL Server Process Queue Race Condition

    - by William Edmondson
    I have an order queue that is accessed by multiple order processors through a stored procedure. Each processor passes in a unique ID which is used to lock the next 20 orders for its own use. The stored procedure then returns these records to the order processor to be acted upon. There are cases where multiple processors are able to retrieve the same 'OrderTable' record at which point they try to simultaneously operate on it. This ultimately results in errors being thrown later in the process. My next course of action is to allow each processor grab all available orders and just round robin the processors but I was hoping to simply make this section of code thread safe and allow the processors to grab records whenever they like. So Explicitly - Any idea why I am experiencing this race condition and how I can solve the problem. BEGIN TRAN UPDATE OrderTable WITH ( ROWLOCK ) SET ProcessorID = @PROCID WHERE OrderID IN ( SELECT TOP ( 20 ) OrderID FROM OrderTable WITH ( ROWLOCK ) WHERE ProcessorID = 0) COMMIT TRAN SELECT OrderID, ProcessorID, etc... FROM OrderTable WHERE ProcessorID = @PROCID

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  • Groovy on Grails: GORM and BitSets?

    - by Visionary Software Solutions
    I don't see anything in the official documentation about unsupported persistence data types, so I'm working under the assumption that types available in the Groovy language should be handled. However, for the following domain class: class DocGroupPermissions { Workgroup workgroup; Document document; BitSet permissions = new BitSet(2) public DocGroupPermissions() {} void setPermissions(boolean canRead, boolean canWrite){ setReadPermissions(canRead) setWritePermissions(canWrite) } BitSet getPermissions() { return permissions } void setReadPermissions(boolean canRead) { permissions.set(0,canRead) } void setWritePermissions(boolean canWrite) { permissions.set(1,canWrite) } boolean getReadPermissions() { return permissions.get(0) } boolean getWritePermissions() { return permissions.get(1) } static belongsTo = [workgroup:Workgroup, document:Document] static constraints = { workgroup(nullable:false, blank:false) document(nullable:false, blank:false) } } I'm getting: 2009-11-15 16:46:12,298 [main] ERROR context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageSource': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.MappingException: An association from the table doc_group_permissions refers to an unmapped class: java.util.BitSet Has anyone run into this before?

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  • See return value in C#

    - by Snake
    Hi, Consider the following piece of code: As you can see we are on line 28. Is there any way to see the return value of the function at this point, without letting the code return to the caller function? Foo.Bar() is a function call which generates a unique path (for example). So it's NOT constant. In VB.NET it's possible by entering the function's name in the Watch, which will then threat it as a variable. But in C# this is not possible, any other tips? PS: rewriting is not an option.

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  • Django models: Use multiple values as a key?

    - by Rosarch
    Here is a simple model: class TakingCourse(models.Model): course = models.ForeignKey(Course) term = models.ForeignKey(Term) Instead of Django creating a default primary key, I would like to use both course and term as the primary key - taken together, they uniquely identify a tuple. Is this allowed by Django? On a related note: I am trying to represent users taking courses in certain terms. Is there a better way to do this? class Course(models.Model): name = models.CharField(max_length=200) requiredFor = models.ManyToManyField(RequirementSubSet, blank=True) offeringSchool = models.ForeignKey(School) def __unicode__(self): return "%s at %s" % (self.name, self.offeringSchool) class MyUser(models.Model): user = models.ForeignKey(User, unique=True) takingReqSets = models.ManyToManyField(RequirementSet, blank=True) takingTerms = models.ManyToManyField(Term, blank=True) takingCourses = models.ManyToManyField(TakingCourse, blank=True) school = models.ForeignKey(School) class TakingCourse(models.Model): course = models.ForeignKey(Course) term = models.ForeignKey(Term) class Term(models.Model): school = models.ForeignKey(School) isPrimaryTerm = models.BooleanField()

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  • How to fetch message body and attachments in XML format from Lotus Domino server from linux using ph

    - by too
    Has anybody some information about accessing Lotus Domino server to fetch entire mail contents by http(s) requests from php linux server? The article by Andrei Kouvchinnikov describes well how to fetch message list in notes mail folders; after obtaining session id during login one can for example select top 100 messages by calling: https://your.server.domain/mail_db/mailbox.nsf/($Inbox)?ReadViewEntries&Start=1&Count=100 And this works perfectly. The arises when I am trying to get message contents (0A1DA5EEB7B65277C12576F50055D811 is an example message unique Id): https://your.server.domain/mail_db/mailbox.nsf/($Inbox)/0A1DA5EEB7B65277C12576F50055D811/?OpenDocument Such request in IE shows frameset with data hard to parse, in less common browsers like Opera it informs about unsupported browser. Ideally if it is possible to fetch notes message contents and all attachments by requesting it in the url, has anybody some information what request would it be? Link to Lotus web calls reference would be even more beneficial.

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  • Adding an attachment to a .NET Email

    - by Velika
    How do I attach a file with a very unfriendly name (like a file with a session Id number in it) but have it attached as another name?The file has the session ID in it to avoid clashes name on the web server nut when I attach it to the file, a friendlier name is preferable. Is there a way to attach the file with teh unfriendly name as anotehr name so that when the user gets the email he can tell from the name what the content of the file is? I'd hate to have to create a unique folder just to put a common file name in it for the purpose of simply attaching it to an email. Dim mailMessage As System.Net.Mail.MailMessage = New System.Net.Mail.MailMessage() mailMessage.Attachments.Add("unfriendlyname.txt", ????)

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  • Django model manager didn't work with related object when I do aggregated query

    - by Satoru.Logic
    Hi, all. I'm having trouble doing an aggregation query on a many-to-many related field. Let's begin with my models: class SortedTagManager(models.Manager): use_for_related_fields = True def get_query_set(self): orig_query_set = super(SortedTagManager, self).get_query_set() # FIXME `used` is wrongly counted return orig_query_set.distinct().annotate( used=models.Count('users')).order_by('-used') class Tag(models.Model): content = models.CharField(max_length=32, unique=True) creator = models.ForeignKey(User, related_name='tags_i_created') users = models.ManyToManyField(User, through='TaggedNote', related_name='tags_i_used') objects_sorted_by_used = SortedTagManager() class TaggedNote(models.Model): """Association table of both (Tag , Note) and (Tag, User)""" note = models.ForeignKey(Note) # Note is what's tagged in my app tag = models.ForeignKey(Tag) tagged_by = models.ForeignKey(User) class Meta: unique_together = (('note', 'tag'),) However, the value of the aggregated field used is only correct when the model is queried directly: for t in Tag.objects.all(): print t.used # this works correctly for t in user.tags_i_used.all(): print t.used #prints n^2 when it should give n Would you please tell me what's wrong with it? Thanks in advance.

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  • Using Parallel Extensions with ThreadStatic attribute. Could it leak memory?

    - by the-locster
    I'm using Parallel Extensions fairly heavily and I've just now encountered a case where using thread locla storrage might be sensible to allow re-use of objects by worker threads. As such I was lookign at the ThreadStatic attribute which marks a static field/variable as having a unique value per thread. It seems to me that it would be unwise to use PE with the ThreadStatic attribute without any guarantee of thread re-use by PE. That is, if threads are created and destroyed to some degree would the variables (and thus objects they point to) remain in thread local storage for some indeterminate amount of time, thus causing a memory leak? Or perhaps the thread storage is tied to the threads and disposed of when the threads are disposed? But then you still potentially have threads in a pool that are longed lived and that accumulate thread local storage from various pieces of code the threads are used for. Is there a better approach to obtaining thread local storage with PE? Thankyou.

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  • OpenID like Stack Overflow

    - by eWolf
    I want to create an OpenID login with PHP just like it can be found on Stack Overflow. I know there are many questions for this, but mine is different. If I understood it correctly, every OpenID is defined by a unique URL. But: If I hit the Google button on the Stack Overflow login page, one generic URL is inserted in the text field. Is this the direct URL to the OpenID server? And if it is, how do I have to pass the URL to this class?

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  • Ways to save enums in database

    - by corgrath
    Hey guys. I am wondering what the best ways to save enums into a database is. I know there are name() and valueOf() methods to make it into a String back. But are there any other (flexible) options to store these values? Is there a smart way to make them into unique numbers (ordinal() is not safe to use)? Any comments and suggestions would be helpful :) Update: Thanks for all awesome and fast answers! It was as I suspected. However a note to 'toolkit'; That is one way. The problem is that I would have to add the same methods with each enum type i create. Thats a lot of duplicated code and, at the moment, Java does not support any solutions to this (You cannot let enum extend other classes). However, thanks for all answers!

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  • Reducing piracy of iPhone applications

    - by Alex Reynolds
    What are accepted methods to reduce iPhone application piracy, which do not violate Apple's evaluation process? If my application "phones home" to provide the unique device ID on which it runs, what other information would I need to collect (e.g., the Apple ID used to purchase the application) to create a valid registration token that authorizes use of the application? Likewise, what code would I use to access that extra data? What seem to be the best available technical approaches to this problem, at the present time? (Please refrain from non-programming answers about how piracy is inevitable, etc.)

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  • Jquery ajax request error callback is called instead of success even after response recieved from server

    - by Muhammad Tahir Butt
    I am using jquery ajax funtion to get some content from my webservice. Response from the server is received but every time error callback is called instead of success callback. And this error is returned in xhr.error: function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this} Here is the screenshot of response from server: and here is the code i am using to make the request: function abcdef() { $.ajax({ url: "http://192.168.61.129:8000/get-yt-access-token/", type: "GET", contentType:"application/json", error: function(xhr, textStatus, errorThrown){ alert("its error! " + xhr.error); }, success: function(data){ alert(data); } }); }

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  • Can django's auth_user.username be varchar(75)? How could that be done?

    - by perrierism
    Is there anything wrong with running alter table on auth_user to make username be varchar(75) so it can fit an email? What does that break if anything? If you were to change auth_user.username to be varchar(75) where would you need to modify django? Is it simply a matter of changing 30 to 75 in the source code?: username = models.CharField(_('username'), max_length=30, unique=True, help_text=_("Required. 30 characters or fewer. Letters, numbers and @/./+/-/_ characters")) Or is there other validation on this field that would have to be changed or any other repercussions to doing so? See comment discussion with bartek below regarding the reason for doing it.

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  • Extend LDAP Membership to append a prefix/sufix to the username

    - by Romias
    Our web applications are using LDAP Membership Provider to authenticate and register users in Active Directory. In order to allow users to provide usernames that exist in other applications, we need to add a prefix in its username and it should be as transparent and painless as possible. What I need is a way to extend the LDAP Membership Provider to be able to add (concatenate) a prefix to the username just before Membership authenticate or register it. For example, if user input is "JohnS" in application 1... I want to authenticate: "App1_JohnS". How could I extend the membership to accomplish this? Any idea what is triggered just before authenticate and register (create user)? Update: Each web app has an "OU" in AD where create users to and authenticate from. But as it is just ONE Active Directory Controller the usernames must be unique. We need to solve this issue using Membership providers and not adding more ADs.

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  • SEO - Problems possibly related to 301 Moved Permanently

    - by ILMV
    Right, here's the story: We have had a website for one of our brands now for many years, the site design was very bad and recently did a complete overhaul, mostly design, but also some of the backend code. The original site was using links such as this example.com/products/item/127 and thus I wanted to change them to be move user friendly, especially to include the product name, the same link now reads example.com/product/127/my-jucy-product/. Since our switch over we have seen our Google results take a beating (we were on the first page for our normal search terms, now we're nearer the 4th!). The other problem we're having is that the links to the old products haven't updated to the new links despite me coding a 301 redirect from old to new. The 301 is not being fired from .htaccess, but in our PHP framework. I had a look at how the site is being loaded from a old link that is still in Google and here's what firebug is reporting: GET <google link> 302 Found GET example.com/products/item/127 302 Found GET example.com/products/item/127 301 Moved Permanently GET example.com/product/127/my-jucy-product/ 302 Found So the Google link has a 302, good. But when the old link comes in our framework is returning a 302! It's only afterwards when it finally hits the right part of the framework does it 301, so here's my question: Is the reason our old links have not changed and our Google Ranking has significantly nose dived because Google is seeing a 302 before the 301? At the time I was reluctant to mess with our .htaccess because it had become pretty complicated and I was under some pretty intense time constraints, now I'm wondering whether this was an incorrect disicion and perhaps I should revisit it. Many thanks! Edit Bugger, just signed up to the Webmaster Tools and I'm getting redirect errors all over the place, hundreds of them! I think this is my problem.

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  • Django syncdb not making tables for my app

    - by Rosarch
    It used to work, and now it doesn't. python manage.py syncdb no longer makes tables for my app. From settings.py: INSTALLED_APPS = ( 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'mysite.myapp', 'django.contrib.admin', ) What could I be doing wrong? The break appeared to coincide with editing this model in models.py, but that could be total coincidence. I commented out the lines I changed, and it still doesn't work. class MyUser(models.Model): user = models.ForeignKey(User, unique=True) takingReqSets = models.ManyToManyField(RequirementSet, blank=True) takingTerms = models.ManyToManyField(Term, blank=True) takingCourses = models.ManyToManyField(Course, through=TakingCourse, blank=True) school = models.ForeignKey(School) # minCreditsPerTerm = models.IntegerField(blank=True) # maxCreditsPerTerm = models.IntegerField(blank=True) # optimalCreditsPerTerm = models.IntegerField(blank=True) UPDATE: When I run python manage.py loadddata initial_data, it gives an error: DeserializationError: Invalid model identifier: myapp.SomeModel Loading this data had worked fine before. This error is thrown on the very first data object in the data file.

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  • Suggest a solution for event notification using nServiceBus

    - by iMahesh
    Currently we are looking for a solution to have unique profile for our user. We are having a different set of applications and the different profiles like is SAP , in DB and in AD too. We want to make sure If user alters his/her profile from any of application it should have replicate in all the data sources. We are looking for NServiceBus as the option for event notification as all subscribed applications will receive notification through bus if there is any change. Can anyone suggest me solution based on the NServiceBus? What pros/cons will be there?

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